National Academies Press: OpenBook
« Previous: 2 Background
Page 4
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 4
Page 5
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 5
Page 6
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 6
Page 7
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 7
Page 8
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 8
Page 9
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 9
Page 10
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 10
Page 11
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 11
Page 12
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 12
Page 13
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 13
Page 14
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 14
Page 15
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 15
Page 16
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 16
Page 17
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 17
Page 18
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 18
Page 19
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 19
Page 20
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 20
Page 21
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 21
Page 22
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 22
Page 23
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 23
Page 24
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 24
Page 25
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 25
Page 26
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 26
Page 27
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 27
Page 28
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 28
Page 29
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 29
Page 30
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 30
Page 31
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 31
Page 32
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 32
Page 33
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 33
Page 34
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 34
Page 35
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 35
Page 36
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 36
Page 37
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 37
Page 38
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 38
Page 39
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 39
Page 40
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 40
Page 41
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 41
Page 42
Suggested Citation:"Report contents." National Academies of Sciences, Engineering, and Medicine. 2018. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels. Washington, DC: The National Academies Press. doi: 10.17226/25095.
×
Page 42

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

3 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. CONTENTS 1. EXECUTIVE SUMMARY ________________________________________________________________________________________ 4 2. BACKGROUND _______________________________________________________________________________________________ 6 2.1. Test Campaigns ___________________________________________________________________________________________ 6 2.2. Aircraft Engines ___________________________________________________________________________________________ 6 2.3. Conventional Jet Fuel ______________________________________________________________________________________ 7 2.4. Synthetic Fuels ___________________________________________________________________________________________ 7 2.5. Sustainable Alternative Jet Fuel Production ___________________________________________________________________ 8 2.6. Pollutant Species __________________________________________________________________________________________ 9 2.7. Report Identification _______________________________________________________________________________________ 9 3. POLLUTANT EMISSIONS _____________________________________________________________________________________ 10 3.1. CO2 and H2O ____________________________________________________________________________________________ 10 3.2. SOx _____________________________________________________________________________________________________ 10 3.3. PM2.5 ____________________________________________________________________________________________________ 10 3.4. CO _____________________________________________________________________________________________________ 11 3.5. UHC ____________________________________________________________________________________________________ 11 3.6. NOx _____________________________________________________________________________________________________ 12 3.7. HAP ____________________________________________________________________________________________________ 12 4. KNOWLEDGE GAPS _________________________________________________________________________________________ 12 4.1. Scope of Testing _________________________________________________________________________________________ 12 4.2. SOx _____________________________________________________________________________________________________ 14 4.3. PM _____________________________________________________________________________________________________ 14 4.4. CO _____________________________________________________________________________________________________ 14 4.5. UHC ____________________________________________________________________________________________________ 14 4.6. NOx _____________________________________________________________________________________________________ 14 4.7. HAP ____________________________________________________________________________________________________ 15 4.8. Future Testing ____________________________________________________________________________________________ 15 5. ANNOTATED BIBLIOGRAPHY _________________________________________________________________________________ 15 6. REFERENCES _______________________________________________________________________________________________ 29 7. APPENDIX __________________________________________________________________________________________________ 32 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

4 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. 1. EXECUTIVE SUMMARY Aviation has a long and successful record of improving operational performance and fuel efficiency over time and is now seeking to reduce its greenhouse gas (GHG) emissions and offset emissions that may result from growing demand for air travel. U.S. and international airlines have committed to reducing lifecycle CO2 emissions from aircraft operations. The primary means for reducing these emissions is using alternative jet fuels produced from non-petroleum sources, referred to as sustainable alternative jet fuels (SAJF). The aviation industry uses an ASTM International specification standard (ASTM D7566) to define alternative fuels that have been approved by the industry as being safe for use in commercial aircraft. To date, five different fuel production pathways have been defined. Table ES-1 summarizes those fuels as well as the number of reports in the literature that evaluated emissions from testing of those synthesized fuels. The industry is presently reviewing additional alternative jet fuel production pathways, which may add new qualified fuels to this list in the future. Figure ES-1 summarizes those fuels and Section 2 of the report defines them in more detail. Annex # Fuel Production Pathway Number of Emissions Tests Reported in Literature A1 Fischer-Tropsch Hydroprocessed Synthetic Paraffinic Kerosene (FT-SPK) 15 A2 Synthesized Paraffinic Kerosene from Hydroprocessed Esters and Fatty Acids (HEFA-SPK) 13 A3 Synthesized Iso-Paraffins Produced from Hydroprocessed Fermented Sugars (HFS-SIP) 3 A4 Synthesized Kerosene with Aromatics Derived by Alkylation of Light Aromatics from Non-Petroleum Sources (FT-SPK/A) 0 A5 Alcohol-to-Jet Synthetic Paraffinic Kerosene (ATJ-SPK) limited initially to the use of ethanol and isobutanol, but eventually intended to allow the use of any C2-C5 alcohol 4 Table ES-1: Industry Approved Alternative Jet Fuels included in ASTM D7566 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

5 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. While the primary purpose for airlines to use SAJF is to reduce CO2 emissions, emissions of other pollutants may also be reduced, which could be significantly beneficial to airports. However, these reductions are not yet well defined, leaving airports unable to realize what may be substantial benefits. The research team team analyzed the published technical literature to validate that SAJF use does reduce air pollutant emissions (i.e., PM2.5, SOx, CO, UHC, NOx) and does not cause any of them to increase. Table ES-2 summarizes the body of literature that was screened to identify essential reports that include quantitative data on results from emissions testing of SAJF. The data in these reports was analyzed in detail to define the impact of using SAJF on air pollutants of interest to airports. The summarization of these reports and their emissions data shows that SAJF, when blended with conventional jet fuel as defined in D7566, significantly reduces SOx and PM, generally reduces CO and UHC emissions, and minimally reduces or has no effect on NOx emissions. Figure ES-2 summarizes the impact of SAJF on aircraft emissions. This report describes why these findings are expected based on an understanding of the mechanisms of pollutant production when burning jet fuel in aircraft engines and how this is repeatedly confirmed by the data collected from numerous tests and measurement campaigns. Following this Executive Summary, Section 2 provides a discussion of the scope of this report including emission testing campaigns, SAJF production and approved fuels, and pollutant species. Section 3 provides information on the source of the different pollutant species that result from fuel combustion. Section 4 describes the knowledge gaps in the current literature and testing to date. Section 5 is an annotated bibliography that highlights key findings from several reports, which influenced the findings of this literature survey. Section 6 includes a complete reference list, and Section 7 is an appendix, which summarizes the impacts of alternative fuels on the emissions of SOx, PM2.5, CO, UHC, NOx, and HAP from individual reports. Figure ES-1: Fuel Production Pathways Currently Undergoing Review Document Hits Search Criteria 35,136 Alternative jet fuel emissions 9,369 Alternative jet fuel emissions + criteria pollutants 73 Alternative jet fuel emissions + criteria pollutants + emission measurements 51 Reports with quantitative emissions analysis (used in this literature review) Table ES-2: Identifying Reports for Literature Review SOx PM2.5 CO UHC NOx HAP 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Neat 50% Blend R ed uc ti o ns (% ) Figure ES-2: Representative Air Pollutant Emission Reductions from the Use of SAJF FUEL PRODUCTION PATHWAY ATJ-SPK; Expansion of Annex A5 (ATJ-SPK) to include the use of ethanol as a feedstock HDO-SAK; Synthesized Aromatic Kerosene via the catalytic conversion of sugars CHJ; Catalytic Hydrothermolysis Jet via Isoconversion of lipids, fats, oils or greases HFP-HEFA; High Freeze Point HEFA, using HDRD (aka Green Diesel) as a blending agent State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

6 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. 2. BACKGROUND This State of the Industry report is a “reference document” that captures the current status of knowledge regarding emissions from the use of sustainable alternative jet fuels (SAJF). The research team conducted a review of available research, literature, and measurement campaigns to enhance our current understanding of the local air quality emissions benefits and impacts of SAJF as well as SAJF blends relative to conventional jet fuel. We drilled down into the data and extracted and analyzed the essential emissions testing data to quantify typical emissions impacts of SAJF use. The review results are focused specifically on air quality emissions of criteria pollutants from SAJF. The report also includes an analysis of gaps in our current understanding of the production of pollutants from SAJF. 2.1. TEST CAMPAIGNS Department of Defense (DoD) and National Aeronautics and Space Administration (NASA) have been primarily responsible for most of the SAJF testing to date. DoD conducted tests on many of the different aircraft they operate to qualify their use of SAJF. NASA has been conducting research on aircraft engine emissions to evaluate their environmental impact for several years. Many of these research programs included DoD research labs, Federal Aviation Administration (FAA) experts, aircraft and engine manufacturers, universities, and scientific experts. Some of the more significant test programs were: • APEX, September 2006 • AAFEX-I, January 2009 • AAFEX-II, March 2011 • ACCESS-I, February-April, 2013 • ACCESS-II, May, 2014 Much of the literature reviewed in this report comes from reports on these projects or analyses of the data produced during these projects. 2.2. AIRCRAFT ENGINES Today’s commercial and military aircraft rely on modern, high-efficiency, sophisticated turbine engines to deliver the safety, operability, and efficiency demanded from the sector. Additionally, auxiliary power units (APU) are smaller turbine engines utilizing similar design principles which also perform consistently and reliably. Aircraft main engines and APUs were the primary test beds for SAJF emissions testing. The various testing campaigns showed that emissions testing on a given engine could produce repeatable and consistent results for any given fuel. However, engine to engine differences are significant. The age/pedigree of the engine, time since last overhaul, and cleanliness of fuel components, such as nozzles, can affect combustion and consequently emissions. For a series of tests performed on a given engine, the changes in emissions will be a reflection of the thrust setting (i.e., fuel flow) and fuel composition. In general, fuel chemistry has a much greater impact on emissions than the difference among engines. The relationship between fuel composition and emissions is discussed below. The emissions tests conducted in the reports included in this literature review were performed at various engine thrust settings intended to reflect an aircraft’s main engine performance. The basis for selecting specific thrust settings correlates with the landing-and-takeoff (LTO) cycle as defined by the International Civil Aviation Organization (ICAO) and used for engine certification testing. As a general representation, taxiing aircraft use low thrust (4%). Full thrust (100%) is used to represent takeoff as the aircraft comes up to speed quickly to get off the ground. Once in the air, the thrust is reduced somewhat (85%) as the aircraft climbs to cruise altitude. A thrust setting of 30% is representative of the thrust an aircraft uses on approach to landing. These thrust settings are commonly used for emissions testing although in actual operation, thrust settings vary and typically are lower than these values. In a similar way, tests conducted on APUs use three power settings – “no load” or “ready-to-load,” environmental control system, and “maximum load” or “main engine start,” which reflect in-use APU thrust settings. The no load setting is equivalent to idle on aircraft main engines. The environmental control system setting is an intermediate power setting used when the APU is providing secondary electric power and ventilation to an aircraft parked at the gate. The main engine start setting is a high-power setting used when starting the aircraft main engines. Aircraft main engines are designed to operate most efficiently at cruise power since the majority of fuel use is during cruise. Lower power operation, such as for idling and taxiing, is less efficient from a fuel combustion standpoint. As a result, emission species that reflect engine efficiency, notably CO and UHC, are higher per unit of fuel consumed at low power operation and lower at high power operation. Conversely, NOx emissions, which State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

7 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. are produced at high temperature, are higher at high thrust and lower at low thrust. Similarly, with an APU, CO and UHC emissions are higher at the “no load” setting and lower at “maximum load” while the reverse is true for NOx. 2.3. CONVENTIONAL JET FUEL Various emissions tests of jet fuel, SAJF, and blends of the two are evaluated in this literature review. Different research groups used different jet fuels in their experiments, which usually reflected the most readily available conventional jet fuel. The different fuels, based on different fuel specifications, however, are very similar. The Jet A specification is used commercially throughout the U.S. and generally not available outside of the country. Jet A-1 specification fuel, which is used outside the U.S., is very similar to Jet A with the primary difference being a slightly lower freeze point for Jet A-1. The U.S. military formerly used JP-8 jet fuel, which is very similar to Jet A-1 but includes a static dissipater, corrosion inhibitor, and anti-icing additives. They have recently changed to Jet A-1 with those additives. The combustion of these three fuels is very similar from an emissions standpoint and for the purpose of this report they are assumed to be equivalent. 2.4. SYNTHETIC FUELS ASTM International, an international standard setting organization, maintains a standard specification D1655 for aviation turbine fuels, referred to as conventional jet fuel. The organization also is responsible for establishing specifications for synthetic blending components, designated D7566. While most of the reports reviewed for this investigation used alternative fuels that would meet D7566, some of the fuels would not meet this specification (even though these studies were conducted prior to publication of the D7566 specification). These include fatty acid methyl ethers (FAME) and ethanol, which are both oxygenated compounds. These emission studies provided useful data illustrating the relationship of fuel composition and emissions. Also, the D7566 specification does not address the sustainability of the fuel per se. Generally, the sustainability of any alternative jet fuel production depends not only on the source of the hydrocarbons used to produce the fuel, but many other measures of societal acceptability associated with the fuel’s production, including economic, environmental, and social factors. Fuel produced from coal, petroleum, or natural gas feedstocks is not considered sustainable, as the feedstocks are fundamentally not renewable. Fuel produced from renewable biological feedstocks (e.g., plant-derived oils, agricultural wastes, forestry residues) or recycled carbonaceous sources (e.g., municipal solid waste, industrial off-gases, atmospheric CO2)), might be considered as meeting the minimum threshold for consideration of sustainability. However, being renewable or recyclable is not a sufficient criterion, and other aspects of societal impact must be evaluated to entitle such fuels as “sustainable.” Determining the sustainability of a given fuel type or production lot is often complex and beyond the scope of this report, but information exists that shows that there are examples of fuels being able to be sustainably produced per the definitions in ASTM D7566 annexes. To date, the aviation industry has added five annexes to D7566 for producing different synthetic blending components. Fuels produced according to these annexes are referred to in this report as sustainable alternative jet fuels (SAJF). 1. Fischer-Tropsch Hydroprocessed Synthetic Paraffinic Kerosene (FT-SPK), uses a synthesis gas feedstock, produced by thermally converting hydrocarbon State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

8 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. materials, which can include various sources of renewable biomass such as municipal solid waste, agricultural wastes, forest wastes, wood, and energy crops. Synthesis gas (CO and H2) is then converted employing catalytic processes in a Fischer-Tropsch (FT) reactor into liquid hydrocarbons such as diesel or jet fuel. FT-SPK must be blended with conventional jet fuel at levels up to 50%. 2. Synthesized Paraffinic Kerosene from Hydroprocessed Esters and Fatty Acids (HEFA-SPK) is produced by reacting an oil or fat-based feedstock, such as fats and oils derived from vegetables, animals, or waste oil, with hydrogen. HEFA-SPK can be blended with conventional jet fuel up to 50%. 3. Synthesized Iso-Paraffins produced from Hydroprocessed Fermented Sugars (HFS-SIP), are produced by hydroprocessing and fractionation of synthetic hydrocarbons derived from the fermentation of plant-based sugars such as sugar, corn, or forest wastes, to produce farnesene, a 15-carbon hydrocarbon molecule. HFS-SIP must be blended with conventional jet fuel, at levels up to 10%. 4. Synthesized Kerosene with Aromatics Derived by Alkylation of Light Aromatics from Non-Petroleum Sources (SPK/A), includes aromatics that can possibly reach higher blend rates than other synthetic fuels. A minimum of 8% aromatics is required in SAJF blends to ensure sufficient seal swell as a way to prevent fuel system leaks. According to the ASTM D7566 specification, the SPK/A synthetic blending component shall be comprised of FT-SPK combined with synthesized aromatics from the alkylation of non- petroleum derived light aromatics, primarily benzene. These fuels must be blended with conventional jet fuel, at levels up to 50%. 5. Alcohol-to-Jet Synthetic Paraffinic Kerosene (ATJ-SPK) is produced from alcohols that have been produced from fermentable sugars which in turn have been produced from renewable feedstocks such as sugar, corn, or industrial or forest wastes. ATJ-SPK to be blended with conventional jet fuel, at levels up to 30% (although as of this writing, an effort is underway to increase the maximum blending level to a higher 50%). Several other fuel production pathways are currently being evaluated under ASTM D7566 for approval as blending components. At the time of this report, the following fuels are in the approval process: 1. HDO-SAK – A bioforming process that converts aqueous carbohydrate solutions into a mixture of aromatic hydrocarbons via a process described as HydroDeOxygenation. 2. Catalytic Hydrothermolysis Jet (CHJ) – A two- step process of catalytic hydrothermolysis and hydroprocessing where bio-oils are converted to hydrocarbons in the jet fuel range using water (under high temperature and pressure) as a catalyst. Alkylation produces aromatics so it is possible the fuel could be used without the need for blending. 3. FHP-HEFA – High Freeze Point HEFA (aka Green Diesel, or HEFA+), is using hydrogenation-derived renewable diesel as a blending agent with jet fuel. 2.5. SUSTAINABLE ALTERNATIVE JET FUEL PRODUCTION The five SAJF approved by the industry in ASTM D7566 each follow a different production process beginning with somewhat different feedstocks, however, the resulting fuel when blended with conventional jet fuel meets the specification for conventional jet fuel. Fuels produced from non-sustainable feedstocks such as coal, petroleum, or natural gas can also meet the ASTM specifications under Annex 1 and perform identically to conventional jet fuel. Some of the emissions testing evaluated for this report were conducted on GTL (gas-to-liquid) fuels. Because they meet the D7566 specification, their emissions performance is equivalent to SAJF and a valid source of data for this analysis. Hydroprocessing is an important step in producing jet fuels, both conventional and SAJF. In refineries producing conventional jet fuel, one of the final steps is treating the fuel with hydrogen in the presence of a catalyst. The hydrogen reacts with sulfur, nitrogen, and other unwanted elements (heteroatoms) present in the fuel to reduce impurities required by internationally accepted fuel specifications. Hydroprocessing at the refinery reduces, rather than eliminates, these components to ensure they are below the allowable limits. Hydroprocessing is also the final step in the five SAJF production pathways approved to date. It is an important step in producing HEFA-SPK fuels to remove oxygen from feedstocks (i.e., deoxygenate). This is typical for feedstocks containing triglycerides such as animal fats and oils from soybeans, palm, algae, jatropha, and other oily plants. In all five SAJF production processes, hydroprocessing essentially removes all sulfur and heteroatoms that may be present. It also converts the fuel stream into a more uniform composition, converting aromatics and high State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

9 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. terms but in this report the differences were ignored. Two of the reports use the chemical class “aldehydes” as a surrogate for HAPs and one report measures formaldehyde (HCHO) as a representative of all aldehydes. This has proven to be reasonable in prior research as indicative of that component of the emissions. Formaldehyde is commonly the most prevalent aldehyde in aircraft engine emissions and the proportion of formaldehyde to the other hydrocarbons in the emissions remains consistent at different emission rates. PM (particulate matter), often referred to as soot, means nvPM (non-volatile PM) when used in this report. Some studies measured PM2.5, which is non-volatile PM smaller than 2.5 micrometers in diameter and is the regulated size classification of PM. Aircraft engine emissions of nvPM are even smaller, in the PM1.0 and smaller range. For the purpose of this report, these terms are assumed to be equivalent. 2.7. REPORT IDENTIFICATION The research team team collected, reviewed, and compiled data from research reports from all aircraft engine emission tests of SAJF and related research projects. This includes testing sponsored by DoD, NASA, FAA, aircraft and engine Original Equipment Manufacturers (OEMs), fuel producers, and other organizations. Missouri University of Science & Technology (MS&T) technical library database, the open Internet, and frequently cited reports were searched to identify the reports in this literature survey. The collected information includes university and government publications, briefings, and other technical reports. Table 1 shows how the universe of reports was reduced to just the reports pertinent for this study. An analysis of these reports and data shows that SAJF, when blended with conventional jet fuel, significantly reduces SOx and PM, generally reduces CO and UHC emissions, and minimally reduces or has no effect on NOx emissions. The variability in emissions data will molecular weight hydrocarbon compounds into straight chain compounds (normal paraffins or n-paraffins). Finally, distillation separates the primary fuel components from lighter and heavier molecules to leave a fuel stream comprised mostly of molecules containing 8-18 carbon atoms. Some branched molecules (iso-paraffins) are present. One significant result of this process is that the synthetic fuels have a higher hydrogen content and higher energy mass density compared to conventional jet fuel. As the volumetric energy density goes up with increased hydrogen content, the mass of fuel used decreases. An indication of the changes to the fuel properties was that frequently during test campaigns, fuel flow and shaft speeds decreased with increasing SAJF blend percentage. These changes are consistent with higher energy mass density of the alternative fuels, which result in a constant energy input with lower fuel mass flow. Higher heating value (BTU/lbm) leads to lower fuel burn and reduced emissions on a mass basis. This improves fuel efficiency and reduces emissions. 2.6. POLLUTANT SPECIES Specific emissions and pollutant species addressed in this report include: • Sulfur oxides expressed as SOx • Non-volatile particulate matter (nvPM also referred to as PM) • Carbon monoxide (CO) • Unburned hydrocarbons (UHC) • Nitrogen oxides expressed as NOx • Hazardous air pollutants (HAP) For some pollutant species, slightly different terms are used in different reports. For example, UHC (unburned hydrocarbons) as used in this report. Other research reports use HC (hydrocarbons), VOC (volatile organic carbon), and THC (total hydrocarbons). There are slight differences in the chemical compounds that makeup these Document Hits Search Criteria 35,136 Alternative jet fuel emissions 9,369 Alternative jet fuel emissions + criteria pollutants 73 Alternative jet fuel emissions + criteria pollutants + emission measurements 51 Reports with quantitative emissions analysis (used in this literature review) Table 1: Identifying Reports for Literature Review State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

10 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. be evaluated in more detail in a subsequent phase of this project. This report describes why these findings are expected based on analysis of the mechanisms of pollutant production when burning jet fuel in aircraft engines and how this is repeatedly confirmed by the data collected from numerous tests and measurement campaigns. 3. POLLUTANT EMISSIONS This section summarizes the findings of the impact of SAJF use on the pollutants of interest. It is an evaluation of the body of literature on SAJF emissions testing. Since we are in the early stages of SAJF production, fuels from only a few different production pathways have been tested. However, the fuels tested meet the D7566 specification so their emissions performance is expected to be an excellent indicator of the emissions performance of predominantly paraffinic fuels produced by future production pathways. 3.1. CO2 AND H2O CO2 and H2O are the primary products of hydrocarbon- based fuel combustion (>99%) and the relative proportion of each species is defined by the H/C ratio of a given fuel. SAJFs typically are found to have higher H/C ratios than conventional fuels (~1%), largely due to the additional hydroprocessing, which is the final step in most fuel production processes. 3.2. SOX SOx emissions are produced by the oxidation of sulfur present in the fuel, and emissions levels are directly proportional to the fuel sulfur content. Typically, the sulfur content in SAJFs is very low (< 0.003%wt) and in the case of blends of SAJFs with conventional fuels the sulfur content is dominated by the level of sulfur in the conventional jet fuel component of the blend (Corporan 2010, Stratton, Corporan 2012, Moses 2008). For conventional jet fuels, typical sulfur levels of 0.3%wt are reported. In Beyersdorf, the authors report the use of pure FT fuels resulted in EISO2 reductions of greater than 90%, and intermediate reductions for blends. Table A.1: Alternative Fuel Impact on SOx Emissions in the Appendix summarizes the SOx emission impacts reported in the literature reviewed for this project. 3.3. PM2.5 PM2.5 as defined in the U.S. National Ambient Air Quality Standards (NAAQS), is a regulatory standard for the criteria pollutant described as fine particulate matter and is based on measuring the mass of the particles with diameters <2.5 micrometers. Particulate matter directly emitted from jet engines and detected at the engine exit plane falls into this category, however, these particles typically have diameters that range in the 10 to 100 nanometers (a nanometer is one thousand times smaller than a micrometer). These particles are the products of incomplete combustion within the engine’s combustor and are largely carbonaceous. The non-carbonaceous particles, referred to as volatile particles, are typically heavy hydrocarbons. The carbonaceous particles are often referred to as non-volatile particulate matter (nvPM) and sometime referred to as soot. They are found to vary monotonically with the aromatic content of the fuel. Suitable metrics for nvPM emissions are (1) the number-based emission index (EIn), which is the number of particles generated per kg of fuel burned, and (2) the mass-based emissions index (EIm), which is the mass of particulate matter generated per kg of fuel burned. The NAAQS is a mass-based regulation. The U.S. does not regulate for particle number emissions, however particle number may be more important for evaluating the health effects of particle emissions, therefore, Eln has attracted more interest recently. Changes in EIn ranged from -22 to -99% (Christy 2015, Timko, Andersen 2011, Dally, Moore, Christy 2017, Chen, Shila, Chan, Colker, Byersdorf, Li 2013, Cain, Huang, Moore, Lobo 2011, Corporan 2010). Changes in EIm ranged from -20 to -95% (Christy 2015, Timko, Andersen 2011, Dally, Moore, Christy 2017, Shila, Chan, Colker, Beyersdorf, Li 2013, Cain, Lobo 2011). And changes in GMD (geometric mean diameter) ranged from -2 to +16% for FAME (Lobo 2011, Timko) and from -12 to +1% for 100% FT and 50% blend (Lobo 2011). Similar reductions were observed but not quantified for SPK (Cain), FT coal (Vander Wal, Timko), and biofuels (Chen). Chen analyzed for sulfate ions present in the nvPM component of the exhaust and found them to be the dominant particle-bound anion. Chen also found them to be reduced in concentration for the range of alternative fuels studied compared to conventional jet fuel. Table A.2: Alternative Fuel Impact on PM2.5 Emissions in the Appendix summarizes the PM emission impacts reported in the literature reviewed for this project. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

11 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. 3.4. CO CO emissions are the product of incomplete combustion. They are quantitatively dependent on engine type, engine combustor technology, and engine combustion efficiency. Factors that influence the production of CO include fuel air ratio, fuel injection/atomization/mixing, combustor inlet conditions, and engine power settings. The net result being that, independent of fuel type burned, for a given engine type, CO emissions are found to decrease with increasing engine power setting since at low power engines operate less efficiently (Boeing). Fuels with higher hydrogen/carbon (H/C) ratios yield greater combustion efficiency and lower CO emissions and therefore modest reductions in CO emissions are observed when SAJFs with higher H/C ratios (10-25% Corpran 2011, Boeing) are compared with conventional fuels (Corpran 2010, Timko, Carter 2011, Corpran 2012, Christy 2015, Andersen 2011). In contrast to the generally observed reductions in CO emissions, for the case of SIP fuels no significant changes in CO were observed when compared to conventional fuels (Roland), and in the case of AATJ-SPK fuels CO was observed to increase compared to conventional fuels for low engine power settings (Edwards). Table A.3: Alternative Fuel Impact on CO Emissions in the Appendix summarizes the CO emission impacts reported in the literature reviewed for this project. 3.5. UHC UHC emissions are the products of incomplete combustion. Factors governing UHC emissions include engine type, combustion efficiency and associated parameters such as combustor temperature and pressure, engine power setting, and the H/C ratio of the fuel. Incomplete combustion can result in both cracking and partial combustion of the fuel. Both processes result in the formation of species not present in the original fuel composition. In seven studies using four engines and three combustor rigs and a range of alternative fuels, changes in UHC emissions appeared to be both engine/ combustor rig and fuel specific, sometimes decreasing (Cain, Beyersdorf, Chen, Li 2013), and in some cases no change was observed (Corporan 2010, Altaher, Chi). Table A.4: Alternative Fuel Impact on UHC Emissions in the Appendix summarizes the UHC emission impacts reported in the literature reviewed for this project. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

12 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. 3.6. NOX NOx emissions arise from the oxidation of nitrogen in the combustor. The primary source of nitrogen in the combustor is that which is present in the combustion air flow. Compared to this atmospheric source, nitrogen chemically bound in the fuel is not considered a significant source of engine NOx emissions. Factors affecting NOx emissions include flame temperature, flame residence time, fuel air ratio, combustor inlet conditions, engine power settings, humidity, ambient temperature, and fuel hydrogen content. Since thermal NOx is not specifically related to fuel composition, it is instead very similar between conventional jet fuel and SAJF. The increased H/C ratio in SAJF noted previously can produce small reductions in NOx emissions due to the lower mass of fuel burned and may also increase the rate of NOx creation due to higher combustion temperature. The evidence that fuel composition indirectly affects NOx emissions is mostly reported to be small, less than 10% (Wey, Li 2013, Cain, Corporan 2010, Bhagwan, Colker, Chan, Chi, Rahmes, Corpran 2010, Andersen 2011, Corpran 2011, TImko, Boeing, Carter 2011, Stratton, Corpran 2012, Del Rosario, Roland, Andersen 2015, Christy 2015, Edwards). The exception was from a study of biofuels by Chen where reductions in NOx of up to 70% were observed. However this study evaluated several oxygenated fuels including ethanol, which resulted in lower combustion temperature for these blends. Among all of the tests specifically reporting NOx emissions, 25 of 45 showed no change in NOx emissions, 9 showed NOx reductions of less than 10%, 7 showed NOx emissions either slightly up or slightly down depending on engine power setting, 2 showed NOx increases of 5% or less, and, as mentioned, 1 showed a 70% reduction. Table A.5: Alternative Fuel Impact on NOx Emissions in the Appendix summarizes the NOx emission impacts reported in the literature reviewed for this project. 3.7. HAP Hazardous air pollutants (HAP) are volatile organic compounds (VOC) found in the UHC component of aircraft exhaust emissions. ICAO reported some examples of HAPs that have been identified as representative pollutants from airport sources including formaldehyde, acetaldehyde, acrolein, 1,3-butadiene, benzene, naphthalene, toluene, xylene and propionaldehyde (ICAO). These compounds play an important role in atmospheric chemistry and urban air quality (ICAO, Leikauf, Koenig) and have major health concerns (Li 2014). Studies concerning the impact of alternate fuels on HAP emissions are extremely limited. Four alternate fuels and their blends with Jet A-1 were studied by Li et al. using an APU as the emissions source. Overall, all four alternate fuels/blends showed equivalent (two HEFA blends) or lower aldehyde emissions (FAE blend) compared to Jet A-1. Formaldehyde appeared to be the dominant aldehyde species (Li 2014). In similar studies by Corporan (Corporan 2012) and Timko discussing the limit of uncertainty for HAPs measurements, no significant differences in HAPs production are seen for the alternate fuels studied. Table A.6: Alternative Fuel Impact on HAP Emissions in the Appendix summarizes the HAP emission impacts reported in the literature reviewed for this project. 4. KNOWLEDGE GAPS As noted in earlier sections of this report, there have been several emissions tests conducted to evaluate the performance of SAJF as well as to measure their emissions. The emissions testing was primarily focused on evaluating emissions of nvPM, however, many of the testing programs also recorded emissions of other criteria pollutants. In light of the evolution of SAJF development, the emissions testing was not systematic or extensive. However, the SAJF tested met the D7566 specification and when blended, the tested fuels met the commercial jet fuel specification D1655. As a result, the emissions performance should be representative of SAJF more broadly. Tests were conducted on a variety of engines ranging from auxiliary power units to commercial aircraft main engines as well as several military aircraft engines. Also, as noted earlier, different fuels produced from different feedstocks were used for blending which may have some (probably minor) effect on emissions. The result is a limited data set to be used for evaluating emissions performance across a range of engines, power settings, pollutant species, and blend percentages. A limited data set results in larger error bars and more limited confidence in the relationship between SAJF composition engine emissions. 4.1. SCOPE OF TESTING Table 2 shows the range of engines tested on different fuels. As noted earlier, emissions testing on a given engine could produce repeatable and consistent results for any given fuel. Engine to engine differences, however, are State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

13 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Conventional Jet Fuel Sustainable Alternative Jet Fuel SAJF Annex A1 FT-SPK Annex A2 HEFA-SPK Annex A3 Annex A4 Annex A5 Engine JP-8 Jet A Jet A-1 FT CTL FT GTL Beef Tallow Camelina Fats & Grease SIP SPK/A ATJ- SPK 131-9 APU B37, A320* √ √ √ √ GTCP85 APU B737 √ √ AE3007 ERJ145 √ √ CFM56 DC8 √ √ √ √ √ CFM56-2 DC8 √ √ √ √ CFM56-5C4 A340 CFM56-7 B737 √ √ √ √ CFM56-7B B737 √ √ F117 C-17 √ √ √ F117- PW-100 C-17 √ √ √ √ PW308C DF 2000 √ √ PW615F Citation Mustang √ √ SaM146 RRJ75 √ √ T63 Bell OH-58 √ √ √ √ √ T63-A-700 Bell OH-58 √ √ √ √ √ √ TF33 √ √ B-52 TF34 A-10 √ √ TPE331-10 J 31 √ √ TPE331- 19YGD J 41 √ √ Table 2: Fuel Testing by Engine Type for Reported Emissions Data State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

14 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. significant. The age of an engine, time since last overhaul, and cleanliness of fuel components, such as nozzles, can affect combustion and consequently emissions. This is even significant for engines of the same type and model number. This presents a challenge in comparing emissions data across multiple tests, hence the need for more systematic testing to refine the results. 4.2. SOX As noted in Section 2, SOx emissions are proportional to the sulfur content of the fuel. However, not all sulfur is emitted as SOx. Some sulfur is retained on the soot particles that make up a large component of nvPM, and there are some aerosol particles that contain sulfur. It would be very useful if researchers could partition sulfur in fuel into SOx, aerosol, and nvPM. While in general, fuel sulfur content is proportional to SOx it is not possible to complete a material balance without knowing where all sulfur emissions go. This is not essential for understanding the air quality impacts of SAJF per se but is important for understanding and tracking the fate of the fuel sulfur. 4.3. PM Significant reductions in PM emissions as a result of using SAJF blends are a positive outcome. For that reason it would be beneficial to more carefully/specifically relate the number based emission index (EIn) (the number of particles generated per kg of fuel burned), and the mass based emissions index (EIm) (the mass of particles generated per kg of fuel burned), to engine thrust to better quantify the overall benefits. Also, since PM emissions are found to vary monotonically with the aromatic content of the fuel, this relationship should be quantified. Additionally, more detailed study of the relationship between PM emissions and the concentration of naphthalene as a share of total aromatics in the fuel is needed. Naphthalene appears to play an outsized role in the production of nvPM emissions from aircraft engines. 4.4. CO Only modest changes are seen in CO emissions between conventional jet fuel and SAJF. They are largely related to engine design and operating conditions. However, the H/C ratio in the fuel influences combustion efficiency. SAJF often have a slightly higher H/C ratio compared to conventional jet fuel as a result of the hydrotreating of the fuel as one of the final steps in most SAJF processing, or due to a higher overall percentage of paraffins and iso-paraffins versus cyclo-paraffins and aromatics. Since the differences are small, the resulting impact on CO emissions is generally small. Specific testing to identify these changes is needed to more carefully relate CO emissions to H/C fuel ratio. Also, since CO emissions are higher at low power due to engines being less efficient at low power, testing should focus on lower power operations, although testing at multiple thrust levels (7%, 30%, 85%, and 100%) is recommended. 4.5. UHC Similar to CO, UHC emissions are related to engine efficiency and are higher at low power since engines are designed to maximize efficiency at high power when engines consume the most fuel. H/C ratio in the fuel influences combustion efficiency. SAJF often have a slightly higher H/C ratio compared to conventional jet fuel as a result of the hydrotreating of the fuel as one of the final steps in most SAJF processing, or due to a higher overall percentage of paraffins and iso-paraffins versus cyclo-paraffins and aromatics. Since the differences are small, the resulting impact on UHC emissions are generally small. Specific testing to identify these changes is needed to more carefully relate UHC emissions to H/C fuel ratio. Also, UHC emissions are higher at low power since engines are less efficient at low power so this testing should focus on lower power testing although testing at multiple thrust levels (7%, 30%, 85%, and 100%) is recommended. 4.6. NOX As noted in Section 3, NOx emissions reflect flame temperature, flame residence time, fuel air ratio, combustor inlet conditions, engine power settings, humidity, ambient temperature, and fuel hydrogen content. Thus, compared to conventional jet fuel, only minor changes in NOx emissions have been detected in SAJF testing and most commonly there has been no change that resulted from increasing the SAJF blend percentage. Because the differences in emissions are small, thorough testing is needed to evaluate NOx emissions, being careful to repeat the same engine conditions (e.g., fuel air ratio, humidity, and ambient temperature) with neat conventional jet fuel and different blend percentages of SAJF for different fuel composition. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

15 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. 5. ANNOTATED BIBLIOGRAPHY This section presents a short description of the scope and contents of the references that reported the most essential findings regarding emissions from SAJF. It includes key findings from emission tests project reports (APEX, AAFEX, etc.), ASTM research reports/annexes, and emissions analysis reports by researchers for FAA, CLEEN, DoD, NASA, ACRP, PARTNER, and ASCENT. Altaher, Mohamed A., Andrews, Gordon E., and Li, Hu, PM Characteristics of Low NOx Combustor Burning Biodiesel and its Blends with Kerosene, Proceedings of ASME Turbo Expo 2013: Turbine Technical Conference and Exposition GT2013, June 3-7, 2013, San Antonio, Texas, USA. This work investigated the particulate number concentrations and size distributions of exhaust gases emitted from a radial swirler based low NOx gas turbine combustor. The tests were conducted under atmospheric pressure and 600K at reference Mach number of 0.017 and 0.023. A baseline of natural gas combustion was compared with a waste rapeseed cooking oil methyl ester biodiesel (WME), its blend with kerosene B20, B50 and pure kerosene. • The most common blending ratio is 20% of biodiesel, termed B20. • The combustion test facility consisted of an air supply fan, venturi flow metering, electrical preheaters, 250mm diameter air plenum chamber, 76mm outlet diameter double passage radial swirler, 76mm diameter throat 40mm long wall fuel injector, 330mm long 140mm diameter uncooled combustor, followed by a bend in the water-cooled exhaust pipe with an observation window on the combustor center line. • Lean combustion low NOx radial swirler flame stabilizers were operated close to 0.5 equivalence ratio at 600K and one atmosphere pressure and were shown to have extremely low PM mass emissions of about 1mg/kg for gas and liquid fuel. B100 could be burnt without any major increase in particle number emissions. Anderson, B.E., et al., Alternative Aviation Fuel Experiment (AAFEX), NASA Project Report NSAS/TM-2011-217059, February 2011. This is a report on the AAFEX project, probably the most extensively studied test of alternative jet fuel use in aircraft engines. All of the testing in this project was on-wing engines tested on the ground and evaluation of neat jet fuel (JP-8), a blend of 50% JP-8/50% Fischer-Tropsch fuel produced from natural gas, a blend of 50% JP-8/50% Fischer-Tropsch fuel produced from coal, neat Fischer-Tropsch fuel from natural gas, and neat Fischer-Tropsch fuel from coal. The test bed was a DC-8 with CFM56 engines owned by NASA. Emissions from the aircraft’s APU were also tested. In addition to NASA Langley and Glenn Research Centers, participating research organizations included: U.S. Air Force Arnold and Wright Patterson Air Force Bases, Aerodyne Research, Inc., General Electric, Harvard University, Missouri University of Science and Technology, Montana State University, Pennsylvania State University, Pratt and Whitney, U.S. EPA, and United Technologies. • “Relative to JP-8, burning alternative fuels generally reduced engine CO, THC, and NOx emissions.” • “HAPs emissions were significantly lower for FT fuels.” 4.7. HAP Only a few of the emissions testing programs had specific evaluations of the composition of the UHC emissions so very limited data on HAP emissions are available. To evaluate HAP emissions, UHC emissions must be evaluated for their component species. Additional testing of each SAJF fuel to measure HAPs in the UHC component of the engine exhaust is needed. 4.8. FUTURE TESTING Going forward, additional, more systematic testing would be beneficial to confirm the findings reported here and to fill gaps in our current understanding. In particular, being able to relate the molecular composition of SAJF, and in particular the H/C ratio, would be especially useful. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

16 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. • “Burning 50% blends of JP-8 and the FT fuels did not produce significant reductions in certification gas species emissions.” • At engine power settings above 30%, the authors found that NOx emissions increase with ambient temperature. • CO emissions dependence on ambient temperature was similar among all fuels studied and only prevalent below 30% engine power settings. • Emissions from two versions of the same engine varied from 2-5 times as much, indicating the importance of conducting tests of neat and blended fuels on the same engine. • Lube oil and similar compounds were between 50-70% of the organic aerosol emissions while products of incomplete combustion were 50-30% of the total. • THC emissions from FT fuels were an average of 37% lower than those for JP-8. • CO emissions were an average of 9% lower than those for JP-8. • NOx emissions were relatively insensitive to fuel type and operating conditions. • “AAFEX results are consistent with previous studies and indicate that engines and aircraft support equipment burning synthetic fuels generate substantially less PM and HAPs emissions than those burning standard petroleum-based fuels.” • 70% of VOC emissions were small molecular weight compounds roughly equally divided between fuel cracking products and partially oxidized products. Anderson, B. NASA Langley Research Center, Alternative Fuel Effects on Contrails & Cruise Emissions (ACCESS-2) Flight Experiment, ACCESS Science and Implementation Teams, 09 January 2015. This is a briefing on the results of the ACCESS-2 Measurement Testing • “Significant Results – No difference in NOx, CO, HC emissions between fuels.” Beyersdorf, A. J., Timko, M. T., Ziemba, L. D., Bulzan, D., Corporan, E., Herndon, S. C., Howard, R., Miake-Lye, R., Thornhill, K. L., Winstead, E., Wey, C., Yu, Z., and Anderson, B. E., Reductions in Aircraft Particulate Emissions due to the use of Fischer–Tropsch Fuels, Atmos. Chem. Phys., 14, 11–23, 2014. Standard petroleum JP-8 fuel, pure synthetic fuels produced from natural gas and coal feedstocks using the Fischer–Tropsch (FT) process, and 50% blends of both fuels were tested in the CFM-56 engines on a DC-8 aircraft. • Dramatic reductions in soot emissions were measured for both the pure FT fuels (reductions in mass of 86% averaged over all powers) and blended fuels (66%) relative to the JP-8 baseline with the largest reductions at idle conditions. • At full power, soot emissions were reduced from 103 to 24 mg kg−1 (JP-8 and natural gas FT, respectively). The alternative fuels also produced smaller soot (e.g., at 85% power, volume mean diameters were reduced from 78 nm for JP-8 to 51 nm for the natural gas FT fuel). • For the pure FT fuels, reductions (94% averaged over all powers) in downwind particle number emissions were similar to those measured at the exhaust plane (84%). However, the blended fuels had less of a reduction (reductions of 30–44%) than initially measured (64%). The likely explanation is that the reduced soot emissions in the blended fuel exhaust plume resulted in promotion of new particle formation microphysics, rather than coating on pre-existing soot particles, which is dominant in the JP-8 exhaust plume. Downwind particle volume emissions were reduced for both the pure (79 and 86% reductions) and blended FT fuels (36 and 46%) due to the large reductions in soot emissions. In addition, the alternative fuels had reduced particulate sulfate production (near zero for FT fuels) due to decreased fuel sulfur content. • Use of the FT fuels resulted in reductions in EIUHC of 40% and in EISO2 of over 90%. Blended fuel emissions of UHCs and SO2 were intermediate between JP-8 and the FT fuels. • No trend with respect to power is seen in the EIBC mass reductions with average FT / JP-8 ratios of 0.14 ± 0.05 and Blend/ JP-8 ratios of 0.34 ± 0.15 for all powers. However, the largest EIN and EIV reductions were seen at mid-powers as a result of a shift in the soot size. These reductions were over 95% for the neat FT fuels and 85% for the blended fuels. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

17 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. • Aerosol volume (and mass) was significantly reduced for all the neat alternative fuels and blends with JP-8, while EIN was only significantly reduced for the neat FT fuels. Bhagwan, R., Habisreuther, P., Zarzalis, N., and Turrini, F., An Experimental Comparison of the Emissions Characteristics of Standard Jet A-1 and Synthetic Fuels, Flow Turbulence Combustion (2014) 92:865–884. The investigated synthetic fuels are (a) Fully synthetic jet fuel (FSJF), (b) Fischer Tropsch synthetic paraffinic kerosene (FT-SPK), (c) FT-SPK+20% hexanol, and (d) FT-SPK+50% naphthenic cut. The measurements are performed in a tubular combustor equipped with a burner based on the principle of air-blast atomization. • At 0.3 MPa of combustor pressure, blending of either hexanol or a naphthenic cut in FT-SPK led to increase in both, CO and NOX formations due to the probable decrease in their atomization qualities. FT-SPK had the highest NOX and Jet A-1 had the lowest NOX owing to the differences in their combustor temperatures (due to difference in their sooting tendencies) at same inlet conditions of reactants. • All investigated fuels in the present work, except the blend of hexanol with FT-SPK, have almost similar characteristics concerning the CO2 production. • At a combustor pressure of 0.8 MPa, lower formation of both CO and NOX were observed for all investigated fuels. With an increase in the combustor pressure from 0.3 MPa to 0.8 MPa, maximum values of EI CO for the all tested fuels were reduced by approximately 70%. The emissions characteristics of the investigated synthetic fuels with the burner are very close to that of standard Jet A-1 fuel at higher pressure conditions (0.54 MPa and 0.8 MPa). Boeing Company, UOP, U.S. Air Force Research Laboratory, Evaluation of Bio-Derived Synthetic Paraffinic Kerosenes (Bio-SPK), Report Version 5.0, Committee D02 on Petroleum Products and Lubricants, Subcommittee D02.J0.06 on Emerging Turbine Fuels, Research Report D02-1739, ASTM International, West Conshohocken, PA, 28 June 2011. This is the second ASTM research report on a new annex for producing SAJF under D7566. Six different companies provided Bio-SPK fuels for testing and testing was carried out at 50% and 100% alternative fuel. Emissions testing was carried out on three different engines: 131-9 APU (used on B737 and A320), TPE331-10, and CFM56-7B. For the first two the baseline fuel was JP-8 and for the latter Jet A. • “The fuel flow with the Bio-SPK blend was 1.3% lower at [the high power] condition on a mass basis due to the higher [lower heating value] of the biofuel.” • “The NOx emissions … were 5% higher with the biofuel blend, but would be slightly less … due to the lower biofuel blend fuel flow.” • For the APU, “the UHC and CO emissions were very low at the [high power] conditions, and were significant only at the [low power] condition. There was a 25% reduction in UHC emissions and a 20% reduction in CO emissions at [low power] conditions, indicating a small improvement in combustion efficiency.” • For the TPE331-10 turboprop engine, “there was no significant difference between the NOx levels from the biofuel or the baseline JP-8 at any power setting. NOx emissions were slightly higher at some conditions, and slightly lower at others. This is also true for the CO data except at the lowest power setting where the biofuel produces a slightly lower CO level.” • “CO and UHC emissions are very low at the higher power settings, and small changes can result in large percentage changes. Unburned hydrocarbons were only significant at the lowest power settings, where they were 5 to 20% lower with the biofuel.” State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

18 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Cain, J., DeWitt, M., Blunck, D., Corporan, E., Striebich, R., Anneken, D., Klingshirn, C., Roquemore, W. M., and Vander Wall, R., Characterization of Gaseous and Particulate Emissions From a Turboshaft Engine Burning Conventional, Alternative, and Surrogate Fuels, Energy Fuels 2013, 27, 2290−2302. Allison T63-A-700 turboshaft engine operated at four power settings. Testing was performed with a specification JP-8, a synthetic paraffinic kerosene, and four two-component surrogate mixtures that comprise compound classes within current and future alternative fuels. • Major gaseous emissions were only slightly affected, with trends consistent with those expected based on the overall hydrogen content of the fuels. However, minor hydrocarbon and aldehyde emissions were significantly more sensitive to the fuel chemical composition. • Nonvolatile PM emissions (soot) were strongly affected by the fuel chemical composition. Paraffinic fuels produced significantly lower PM number and mass emissions relative to aromatic-containing fuels, with the paraffin structure affecting sooting propensity. • The CO emissions for the paraffinic fuels were reduced by approximately 10−20% (compared to JP-8) over the full range of power conditions evaluated. Notably, the CO and CO2 emissions for the m-xylene/C12 blend were equivalent to those for JP-8, which could be expected since the hydrogen content of these fuels was almost identical. The trends for the total unburned hydrocarbon emissions were consistent with those for CO, with a 10−20% reduction (compared with JP-8) at the lowest power setting. The total NOx (NO + NO2) emissions were minimally affected during operation with the various fuels, which is reasonable since the formation of these species is primarily thermally driven and the turbine exit temperature was maintained constant. • All fuels produced similar unimodal particle size distributions, with higher sooting fuels producing larger mean diameter particles. On the basis of similarities in the nonvolatile particle size distributions, it is hypothesized that the fuel composition primarily affects the overall PM formation rate, but the controlling growth and formation mechanisms are similar. This hypothesis was supported by TEM analysis that showed that the soot microstructure was similar during operation with the different fuels. The effect of fuel composition on the total PM mass emissions was consistent with that for the overall particle number emissions, but mass reductions were slightly higher due to shifts in the size distributions to smaller particle size. Carter, N., Stratton, R.W., Bredehoeft, M.K., and Hileman, J.I., Energy and Environmental Viability of Select Alternative Jet Fuel Pathways, 47th AIAA/ASME, SAE, ASEE Joint Propulsion Conference & Exhibit, San Diego, CA, AIAA 2011-5968, 31 July – 03 August 2011. This report compared emissions of NOx, PM2.5, CO, and UHC from conventional commercial and military jet fuels with SAJF from Fischer-Tropsch, Biomass-to-Liquid (BTL), and Hydroprocessed Renewable Jet (HRJ) processes. The data compared in this analysis is taken from multiple project reports, which are included in the bibliography for the present report. • “…NOx emissions from military aircraft tend to be lower while primary PM2.5, CO, and UHC emissions tend to be higher than their civilian aircraft counterparts. This is indicative of military aircraft being less efficient at lower power settings than civil aircraft during the LTO cycle.” • “Emissions were … energy normalized by the fuel specific energy using the lower heating value provided in each test document.” • For 100% SPK with emissions normalized to conventional jet fuel, NOx ranged from 0.91-1.01, CO ranged from 0.74- 0.87, and UHC ranged from 0.68-0.76. • For 50% SPK blends with emissions normalized to conventional jet fuel, CO ranged from 0.83-0.91 and UHC ranged from 0.76-0.86; NOx was not reported for fuel blends. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

19 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Chan, T.W., Chishty, W. A., Canteenwalla, P., Buote, D., and Davidson, C.R., Characterization of Emissions From the Use of Alternative Aviation Fuels, Journal of Engineering for Gas Turbines and Power Journal of Engineering for Gas Turbines and Power, January 2016, Vol. 138 / 011506-1. The test engine used in the investigation was a General Electric CF-700-2D-2 turbofan engine. Steady state operation was conducted at three engine load settings: ground idle, 80%, and 95%, corresponding to roughly 8000, 14,000, and 16,000 engine rpm, respectively. The latter two settings represent the aircraft cruise and takeoff conditions. Fully (unblended) SKA. This fuel is produced by a process known as catalytic hydrothermolysis (CH), which converts plant oils into high-density aromatic, cycloparaffin, and iso-paraffin hydrocarbons. The test fuel used in the study was derived from an industrial feedstock called brassica carinata, which is a high yield oilseed and optimally suitable for jet fuel production. This fuel is referred to as 100% CH-SKA in the paper. Fully (unblended) SPK derived from synthesis gas and through the FT process using iron or cobalt as catalyst. The FT-SPK fuel typically contains a complex mixture of paraffins and isoparaffins but contains no aromatics or sulfur. The test fuel used in the study was derived from coal and natural gas in a two-to-one ratio by volume. It is referred to as 100% FT-SPK in this paper. Semisynthetic HEFA synthesized paraffinic kerosene was blended (in 50–50 proportion by volume) with Jet A-1 fuel. The oilseed feedstock for HEFA-SPK fuel was Camelina sativa, which is an industrial nonfood crop. The production of this fuel involves the hydrotreating and/or hydrocracking processes, which produces paraffinic hydrocarbon, and the fuel typically contains no aromatics or sulfur. In the paper, the 50–50 fuel blend is referred to as 50% HEFA-SPK. • In general, operating the engine on various fuels had a small impact on the gaseous emissions. Among all fuels, operating on Jet A-1 generated the highest CO2 emissions, followed by the 100% CH-SKA, 50% HEFA-SPK, and then 100% FT-SPK. The NOx emissions for various fuels at idle condition were about 2 g/kg fuel and slightly over 4 g/kg fuel at 95% engine load. • Relative to Jet A-1, the particle number emissions from the 100% CH-SKA fuel showed moderate reductions of 7–25% over the range of engine load conditions. While for the 50% HEFA-SPK and 100% FT-SPK fuels, the particle number emissions reductions were from 40–60% and 70–95%, respectively. • BC mass emissions from various alternative fuels indicated similar reduction trend with respect to Jet A-1. For 100% CH-SKA fuel the reduction was in the range of 38–50% over the various engine loads. When switching to the 50% HEFA- SPK fuel, the reductions were about 58–82% while the 100% FT-SPK fuel showed BC emissions reduction of 70–95%. The BC mass emissions for the Jet A-1 and the three alternative fuels correlated well with the variations in the aromatic and hydrogen contents and H/C ratio in the fuels. Chen, L., Zhang, Z., Lu, Y., Zhang, C., Zhang, X., Zhang, C., Roskilly, A., Experimental Study of the Gaseous and Particulate Matter Emissions from a Gas Turbine Combustor Burning Butyl Butyrate and Ethanol Blends, Applied Energy 195 (2017) 693–701. This paper reports the gaseous pollutants and particulate matter (PM) emissions of a gas turbine combustor burning butyl butyrate and ethanol blends. The gas turbine has been tested under two operational conditions to represent the cruise (condition 1) and idle (condition 2) conditions of aero engines. Aviation kerosene RP-3 and four different biofuels using butyl butyrate (BB) and ethanol blends were tested and compared to evaluate the impact of fuel composition on CO, NOx, unburned hydrocarbon (UHC), and PM emissions under the two operational conditions. Results indicated that under idle and cruise conditions the CO emissions from butyl butyrate and ethanol blends were higher than that of RP-3 due to the relatively lower combustion temperature of the biofuels compared with that of RP-3. Results of the NOx emission comparison indicated the biofuels produced less NOx than RP-3 and the increase of ethanol content in the biofuels could reduce the NOx and UHC emissions. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

20 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. PM mass emission index at cruise was higher than that at idle for the biofuels, while the trend was opposite to that of RP-3. The concentration of CO emissions from biofuel blends was significantly higher than that of RP-3 during both cruise and idle states. The increase of the ethanol content in the biofuels led to a rise of CO emissions. The biofuel blends effectively reduced the NOx emissions by up to 70.4% compared with RP-3 under both cruising and idling states. The increase of ethanol fraction could further depress the NOx emissions. Biofuels produced less UHC than RP-3 by at most 60.9% (BE-50) except for pure butyl butyrate. The combustion temperature and the oxidation effect by oxygen compositions in the fuels are two primary factors influencing UHC emissions. To all biofuels, particles smaller than 20 nm dominated particle number emissions under cruise, and the concentrations decreased dramatically as particle size increased larger than 20 nm. Ca2+ turned out to be the majority ion among the five cation ions and its molar percentage increased from 18.1% to 36.6% with increasing ethanol content. Christie, S., D4.3 Emissions Report and Database of Systems Key Performance Parameters, ITAKA Collaborative Project, FP7-308807, 30 April 2015. This project report describes emissions testing of a HEFA fuel produced from used cooking oil. Emissions tests were performed using Garret Honeywell GTCP85 APU. Tests were run at 3 power levels typical of APU operation: idle/no load, environmental control system/intermediate load, and main engine start/highest power. The fuel was off-spec as a result of elevated aromatics (1.4% compared to 0.5% limit for ASTM D7566). The tested blends were from 0-100% HEFA combined with Jet A-1. • “… engine performance data showed … reduction in fuel flow in proportion to the mass-corrected specific energy density of the fuel blend.” • “…reduction in smoke number with blend ratio was linear to a good approximation” and “… the rate of reduction with blend ratio was approximately the same for all engine conditions.” • “… both the number and mass based emission indices for [nvPM] reduce almost linearly with increasing … blend fraction.” • “For gaseous emissions, no statistically significant change in the emissions of NOx or UHC was observed with increasing … blend fraction.” • Changes in ambient conditions (temperature, relative humidity, and pressure) showed a slight correlation with UHC emissions. • No correlation between NOx emissions and ambient conditions was observed. • “… a small but statistically significant reduction in CO was observed with increasing … biofuel fraction.” • Slight correlation of CO emissions with ambient temperature and pressure. • Data in this report show that “the change in the emission indices for the species CO, UHC, NOx with increasing biofuel blend fraction is either null or edging towards a modest decrease with increasing blend ratio.” Christie, S., Lobo, P., Lee, D., Raper, D., “Gas Turbine Engine Nonvolatile Particulate Matter Mass Emissions: Correlation with Smoke Number for Conventional and Alternative Fuel Blends,” Environ. Sci. & Techn. 2017, 51, 988- 996. • This study evaluates the relationship between the emissions parameters of smoke number (SN) and mass concentration of nonvolatile particulate matter (nvPM) in the exhaust of a gas turbine engine for a conventional Jet A-1 and a number of alternative fuel blends. • The data shows that correlation between SN and nvPM mass concentration still adheres to the first order approximation (FOA3), and this agreement is maintained over a wide range of fuel compositions. • The study used a Garrett Honeywell GTCP85-129 auxiliary power unit (APU). • The chemical composition of the test fuels was managed by introducing various blends of Jet A-1 and a used cooking oil derived, hydrotreated esters and fatty acid (UCO-HEFA) kerosene. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

21 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. • Hence, on the microscopic scale, the fuel-induced reduction in the mass of emitted nvPM corresponds to the emission of fewer and smaller units of particulate matter. Colket, M., Heyne, J., Rumizen, M., Gupta, M., Jardines, A., Edwards, T., Roquemore, W. M., Andac, G., Boehm, R., Zelina, J., Lovett, J., Condevaux, J., Bornstein, S., Rizk, N., Turner, D., Graves, C., Anand, M.S., An Overview of the National Jet Fuels Combustion Program, AIAA SciTech Forum 54th AIAA Aerospace Sciences Meeting, 4-8 January 2016, San Diego, California. • Several ground-based engine tests (PW308 in March 2008; AAFEX-I in January 2009 and AAFEX-II in March 2011) were conducted to evaluate alternative fuel effects on emissions under real-world conditions. The AAFEX ground tests used the NASA DC-8 aircraft with CFM56-2-C engines, testing JP-8, Fischer-Tropsch (F-T), F-T blends, Hydrotreated Renewable Jet fuels (HRJ), HRJ blends, and high-sulfur F-T. Results showed that these alternative fuels and blends had a minor effect on gaseous emissions. No effect on engine performance was evident within the accuracy of the data. Volatile and non-volatile combustion-generated particulates were substantially reduced when operating with the alternative fuels. • The follow-on to the AAFEX ground tests was the ACCESS (Alternative Fuel Effects on Contrails and Cruise EmiSSions) flight test program using a low-sulfur Jet-A and a 50/50 Jet-A/HEFA blend. Seven 4-hour test flights were conducted May 5-30, 2014 using the NASA DC-8 aircraft with CFM56-2-C engines. Sampling of engine exhaust was conducted using three chase aircrafts (NASA HU-25, DLR Falcon 20 and NRC Canada T-33) which measured gaseous species (CO2, CO, CH4, H2, hydrocarbons, H2SO4, NO, NO2, O3), fine (> 10 nm) and ultrafine (> 5 nm) aerosols, soot mass, and aerosol composition. There was no difference in DC-8 performance or fuel system operation between the fuels, nor any difference in NOx, CO or HC emissions. The 50/50 Jet-A/HEFA blend did reduce soot particle number and soot mass emissions by 50% relative to the low-sulfur Jet-A for ground and at cruise. Corporan, E., DeWitt, M.J., Klingshirn, C.D., Anneken, D., Alternative Fuels Tests on a C-17 Aircraft: Emissions Characteristics, Air Force Research Laboratory, Interim Report, AFRL-RZ-WP-TR-2011-2004, Wright-Patterson Air Force Base, OH, December 2010. This is a report on emissions testing conducted on a military C-17 aircraft positioned on the ground. The aircraft engines were F117-PW-100, equivalent to PW2000, which are commonly used on Boeing 757-200 aircraft. The base jet fuel used was JP-8, which was tested neat and also blended with a beef-tallow-derived hydroprocessed renewable jet fuel and a coal derived Fischer-Tropsch fuel. Blends of 50/50 JP-8/HRJ and 50/25/25 JP-8/HRJ/FT were evaluated. • “… significantly lower CO emissions (20-40%) were observed with the fuel blends. This could be attributed to the environmentally favorable chemical composition (lower carbon-to-hydrogen ratio…) and reduced ring compounds in the fuel blends, which contributed to improved combustion characteristics particularly at lower combustion temperatures” (lower thrust levels). • “Test data also show negligible differences in nitrogen oxide (NOx) emissions between the fuels.” • “Results show that HAPs are more prevalent at low engine power and that formaldehyde was the most dominant HAP for this engine…” • “Lower [HAP] emissions … were produced with both fuel blends compared to JP-8.” Corporan, E., Edwards, T., Shafer, L., DeWitt, M.J., Klingshirn, C.D., Zabarnick, S., West, Z., Striebich, R., Graham, J., Klein, J., Chemical, Thermal Stability, Seal Swell, and Emissions Studies of Alternative Jet Fuels, Energy & Fuels, 2011, 25, 955-966, 2 March 2011. This report presents the results of testing six alternative jet fuels, three Fischer-Tropsch fuels and three HRJ fuels. Emissions test results were compared to emissions testing of JP-8. The test bed for emissions testing was a T63-A-700 turboshaft engine. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

22 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. • One of the Fischer-Tropsch fuels was produced from coal and the other two were produced from natural gas. • The three HRJ fuels were from a mixed feedstock of waste fats and greases (primarily poultry fat), camelina oil, and beef tallow. • All six synthetic fuels had very low aromatics, negligible sulfur, higher heat of combustion, and higher hydrogen content compared to JP-8. • “Gaseous emissions … show that the alternative fuels had negligible impact on CO2, NOx, and formaldehyde; however, statistically significant reductions in carbon monoxide (CO) and UHC were observed.” • “Reductions of 10-25% in CO were observed with the various alternative fuels relative to JP-8.” • “… moderately lower (~20-30%) UHC were produced with the SPK fuels compared to JP-8.” • “Emissions data demonstrate that the neat paraffinic fuels produced significantly lower soot and moderately lower unburned hydrocarbons and carbon monoxide than baseline JP-8 fuel.” Corporan, E., DeWitt, M.J., Klingshirn, C.D., Anneken, D., Shafer, L., Striebich, R., Comparison of Emissions Characteristics of Several Turbine Engines Burning Fischer-Tropsch and Hydroprocessed Esters and Fatty Acids Alternative Jet Fuels, Proceedings of ASME Turbo Expo 2012, Copenhagen, Denmark, 11-15 June 2012. The report summarizes the impacts of alternative jet fuels, both neat fuels and blends, on gaseous and particulate matter emissions of aircraft turbine engines. The following engines were studied: T63 (military turboshaft), CFM56-7, CFM56- 2, F117, TF33, and PW308. The fuels studied were Fischer-Tropsch fuels produced from coal and natural gas and hydroprocessed esters and fatty acids (HEFA) from animal fats and plant oils, all of which were compared to JP-8 for these studies. • “Gaseous emissions measurements show modest reductions of carbon monoxide, unburned hydrocarbons and hazardous air pollutants (HAPs) with the alternative fuels for several engines; however, no clear dependency of fuel impacts based on engine characteristics were observed.” • Heats of combustion from all of the SAJF were higher than the conventional jet fuel. Similarly, and related, the hydrogen content of the SAJF were higher than the conventional jet fuel. • “Identifying a particular combustor characteristic [fuel atomizers, combustor type (annular or tubular)] to correlate with emissions was not possible in this study.” • “In general, differences in most gaseous emissions between baseline and blended fuels for all the engines tested were relatively small.” • “Most relative CO emissions with the neat alternative fuels and blends were between 0.8-1.0, with no dependency on engine power.” • “The lower carbon content in the neat alternative fuels theoretically contributes to reduced CO emissions; however, these differences are relatively small.” • “Similar minor reductions in unburned hydrocarbons emissions were also observed.” • “Negligible differences in NOx emissions for the fuel blends were observed.” • “Investigation of engine operation with alternative fuels and blends on the production of HAPs is of interest to determine if the selectivity of these trace compounds is impacted.” • “For the limited measurements performed, the aldehyde [HAP] emissions with the alternative fuels (and blends) show no significant differences from those for JP-8; however, additional measurements are merited to further evaluate if the production of these HAPs is affected.” • “It is notable that although the SPK/HEFA fuels are aromatic-free, they do produce aromatic species (soot precursors) and subsequently soot during combustion.” State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

23 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Dally B., “Reduced Emissions via Synthesized Aromatic Kerosene”, ASCENT Seattle WA, Oct 2015. Investigated: Fuel composition, total aromatics, simulated altitudes, engine conditions, gaseous emissions (CO, CO2, THC, NO, NOx), and particle emissions (total PM, nvPM number, mass, and size). • Fuels: Jet A, JetA/HEFA, and SAK/HEFA • Simulated altitudes (Kft): 27, 29.5, 37, 39, 40 • Observed significant reductions in nvPM number and mass due to SAK blends; approximately 35-70% over a range of power and altitudes. • No detectable difference in combustor performance from SAK blends vs. Jet A blends. Del Rosario, R., Koudelka, J., Wahls, R., Madavan, N., Bulzan, D., Alternative Aviation Fuel Experiment II (AAFEX II) Overview, 19 September 2012. This is a briefing to the Interagency Working Group on Alternative Fuels that provides highlights of the AAFEX II test. • “Negligible effect of fuel type on engine performance when compared on mass measurement basis and corrected for heating value within accuracy of measurements.” • “Slight reduction in NOx emissions at higher power conditions for F-T fuel.” • “Scatter in CO and HC emissions at idle and sub-idle due more to temperature effects than fuel type.” Edwards, T., Meyer, D., Johnston, G., McCall, M., Rumizen, M., Wright, M., Evaluation of Alcohol to Jet Synthetic Paraffinic Kerosenes (ATJ-SPK), Report Version (1.10), Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants, Subcommittee D02.J0 on Aviation Fuels, Research Report D02-1828, ASTM International, West Conshohocken, PA, 1 April 2016. This is the fifth ASTM research report on a new annex for producing SAJF under D7566. Five different fuel providers produced ATJ-SPK using a variety of alcohol feedstocks (also referred to as Alcohol-to-Jet ATJ). A blend of 50% ATJ- SPK and conventional jet fuel plus 100% ATJ-SPK were tested in a variety of engines (AE 3007 combustor section, TFE34 engine, PW615F engine, and TPE331 engine). • The 50/50 fuel blend “produced somewhat higher CO and UHC at low power conditions and comparable NOx levels to the baseline JP-8.” • When tested on the PW 615F, “no negative impact was observed on [specific fuel consumption], gaseous emissions (CO, HC, CO2, NOx), smoke number, or PM. • For the TPE331-10YGD engine, testing “demonstrated an average of 0.9 percent lower fuel flow and 1.1 percent higher SFC (specific fuel consumption) with the 50/50 blend of … ATJ and JP-8 compared to the baseline JP-8 fuel at the various ambient temperatures, engine speeds, and torque ranges tested in the dynamometer test cell. These lower measured fuel flows can be attributed to the 0.9 percent higher net heat of combustion of the ATJ blend … relative to the JP-8 baseline fuel.” Li, H., et al., Influence of Fuel Composition, Engine Power, and Operation Mode on Exhaust Gas Particulate Size Distribution and Gaseous Emissions from a Gas Turbine Engine, Proc. ASME Turbo Expo 2013, GT2013-94854. The impact of fuel composition, engine power (idle and full power) and operation mode (cold and hot idle) on the gaseous emissions, particle number and mass concentrations, and size distributions from an aircraft auxiliary power unit (APU) was investigated. A re-commissioned Artouste MK113 APU engine was used. • Alternate fuels studied (with respect to Jet A1): - 100% GTL - 50% HEFA/50% JetA1 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

24 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. - 50% HEFA/50% Napthenic cut - 10% FAE/90% JetA1 - 75% HEFA/25% JetA1 • At the idle condition, NOx emissions were slightly greater for 50% HEFA/50% Napthenic cut; ~2.3g/kg than JetA1 (2.2g/ kg. • Alternative fuels produced similar or slightly lower NOx emissions compared to JetA1. • JetA1 produced the highest number and mass peak particle emissions, especially for mass size distributions. The GTL fuel produced the much lower number and mass peak particle emissions at cold and hot idle, indicating an excellent performance for low engine power combustion. • There were clear correlations between fuel H/C ratio and particle number and mass emission distributions in terms of concentration, emission index EIn and EIm, and particle diameter GMD. As the fuel H/C ratio increased, particle concentration, EIn and EIm and GMD were decreased. This is because the fuel H/C ratio essentially is a reflection of fuel hydrocarbon compositions. • In general, alternative fuels/blends had similar levels of NOx emissions with JetA1 at both idle and full power conditions due to the similar flame temperatures for all the fuels. The reduced CO and UHC at idle from alternative fuels/blends demonstrated improved combustion performance due to higher contents of paraffinic hydrocarbons and lower fractions of aromatic hydrocarbons in alternative fuels and their blends compared to JetA1. Li, H., Altaher, M., Wilson, C., Blakey, S., Chung, W., Rye, L., Quantification of Aldehydes Emissions from Alternative and Renewable Aviation Fuels using a Gas Turbine Engine, Atmospheric Environment 84 (2014) 373-379. In this research, three renewable aviation fuel blends, including two HEFA (Hydrotreated Ester and Fatty Acid) blends and one FAE (Fatty Acids Ethyl Ester) blend with conventional Jet A-1 along with a GTL (Gas to Liquid) fuel, have been tested for their aldehydes emissions on a small gas turbine engine. An Artouste MK113 APU (Auxiliary Power Unit) engine was used as a test bed for the emission measurements. Overall, all four alternative fuels/blends showed equivalent or lower aldehyde emissions compared to Jet A-1. Formaldehyde appeared to be the dominant aldehyde species. The detailed conclusions are as follow: • Two HEFA/Jet A-1 fuel blends (fuels F and I) had similar emissions for all three aldehydes at three engine operational modes with Jet A-1. • The FAE blend (fuel H) showed decreased values at idle and increased values at full power for formaldehyde emissions. The contradictory effect of the FAE blend between idle (lower than Jet A-1) and full power (higher than Jet A-1) could be due to the trade-off between positive effect (improved oxidation by fuel born oxygen) and negative effect (deteriorated atomisation caused by higher viscosity and low volatility) of FAE. • Neat GTL fuel achieved notable reductions in formaldehyde (~30%) and acrolein (36-64%) at idle compared to Jet A-1. The lower formaldehyde emissions could be because of its lower tendency for scissions due to its straight carbon chain. Overall, formaldehyde emissions were 2-3 times higher at idle than that at full power. Lobo, P., Hagen, D., Whitefield, P., Comparison of PM Emissions from a Commercial Jet Engine Burning Conventional, Biomass, and Fischer-Tropsch Fuels, Environmental Science & Technology, 1 November 2011. This paper presents the results of a comparison of particulate matter (PM) emissions from a commercial jet engine (CFM56- 7B) burning several alternative biomasses (fatty acid methyl ester, FAME) and F-T-based fuels, and their blends with Jet A1. The engine was cycled through a matrix of reproducible engine power settings where for each power setting steady-state emissions and engine data were recorded. The engine power settings selected were as follows: 3%, 7%, 30%, 45%, 65%, 85%, and 100% rated thrust. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

25 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. • For all fuels studied, the PM emission size distribution at all engine power settings was found to be log-normal. • For a given fuel, GMD, EIn, and EIm increased linearly with engine power setting from 7% to 100% rated thrust. • Both EIn and EIm were found to decrease with decreasing fuel aromatic content at each of the four operational points in the LTO cycle. The largest reduction in EIn was observed when emissions at 7% power for the Jet A1 and 100% F-T fuels were compared, where the aromatic contents were 18.5% and ~ 0% respectively. • Factors relating to fuel oxygen content and viscosity mitigate the reduction of PM associated with reduced fuel aromatic content for the 20% FAME and 40% FAME fuels. Moore, R., et al., Biofuel blending reduces PM emissions from aircraft engines at cruise conditions, Nature 21420, doi:10.1038. This report presents observations from research aircraft that sampled the exhaust of engines onboard a NASA DC-8 (CFM56-2-C1) aircraft as they burned conventional Jet A fuel and a 50:50 (by volume) blend of Jet A fuel and a biofuel derived from camelina oil. • It shows that, compared to using conventional fuels, biofuel blending reduces particle number and mass emissions immediately behind the aircraft by 50 to 70 per cent. • The tests were conducted during 2013–2014 as part of the Alternative Fuel Effects on Contrails and Cruise Emissions Study (ACCESS) at NASA Armstrong Flight Research Center in Palmdale, California, USA. • The greatest effect on emissions is associated with a reduction in black-carbon-equivalent mass, with the biofuel blend exhibiting emission that are 30%–50% of those seen for the petroleum-based Jet A fuels. • “…blending petroleum-based fuels with a HEFA biojet fuel reduces the volatile and non-volatile particle emissions by 50%–70% at atmospheric cruise conditions.” Moses, C.A, Comparative Evaluation of Semi-Synthetic Jet Fuels (FT-SPK), Final Report, Coordinating Research Council, Inc., Universal Technology Corporation, CRC project No. AV-2-04a, Alpharetta, GA, September 2008. This report to the Aviation Committee of the Coordinating Research Council was requested by ASTM to confirm production of alternative jet fuels on which specification D7566 initially was based. It reports on the testing of five semi-synthetic paraffinic jet fuels produced via Fischer-Tropsch technology, one fuel from coal and four fuels from natural gas. The fuels were blended with Jet A, Jet A-1, or JP-8 to a 50/50 blend. Following production of synthesis gas via Fischer-Tropsch and subsequent production of mixed hydrocarbon streams, the final step in each process was hydroprocessing, which produced a synthetic kerosene with high hydrogen content relative to base jet fuel and high net heat of combustion. The neat fuels are essentially free of sulfur and aromatic compounds. This led to approval of generic Fischer-Tropsch fuels under ASTM specification D7566. No emissions testing was reported in the report. Moses, C., Evaluation of Synthesized Aromatics Co-Produced with Iso-Paraffinic Kerosene for the Production of Semi-Synthetic Jet Fuel (SKA), Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants, Subcommittee D02. J0 on Aviation Fuels, Section D02.J0.06 on Emerging Turbine Fuels, Research Report D02-1810, ASTM International, West Conshohocken, PA, 1 November 2015. This is the fourth ASTM research report on a new annex for producing SAJF under D7566. This synthetic jet fuel is similar to FT-SPK with the inclusion of aromatics intentionally produced in a final reaction step. This annex to the D7566 specification allows for 50% SKA blended with conventional jet fuel. No emissions testing is presented in this research report used to support approval of the annex. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

26 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Rahmes, T., et al., Sustainable Bio-Derived Synthetic Paraffinic Kerosene (Bio-SPK) Jet Fuel Flights and Engine Tests Program Results, 9th AIAA Aviation Technology, integration and operations conference, AIAA 2009-7002, Sept 2009. This report documents the progress in the use of sustainable, naturally derived oils to produce 50% Bio-SPK blends that were tested in commercial aircraft, systems, and engines. The feedstock selection and processing methods used to produce a SPK will be discussed, as will the fuel property testing, engine performance, operability and emissions results, and flight test results. A reduction in NOx and smoke emissions was observed with Bio-SPK addition to the conventional jet fuel, although the impact on NOx emissions (~1-5%) can be considered quite small, especially considering the level of uncertainty associated with the test. • The large variation in HC levels cannot necessarily be attributed to fuel properties. • The observed increase in CO and HC emissions might also be explained by the reduction in flame temperature. • The addition of the Bio-SPK to the conventional jet fuel was found to have insignificant effects on emissions. • There was a slight reduction in NOx (~1-5%), and an increase in the CO (~5-9%) and HC emissions (~20-45%). • These observed changes in NOx, CO, and HC emissions are primarily explained by the anticipated reduction in the flame temperature. • Additionally, the impact on spray quality and flame location is also expected to play a major role for emissions levels, especially for CO and HC. • Lower smoke emissions (~13-30%) were also observed. • The emissions tests of the regulated species were compared for the jet fuel, 50%, and 100% ratios used, and showed no significant changes in HC, CO, or NOx. The smoke number decreased as the percentage of the biofuel to Jet A-1 was increased. Roland, O., Garcia, F., TOTAL New Energies, Amyris, Inc., U.S. Air Force Research Laboratory, Evaluation of Synthesized Iso-Paraffins Produced from Hydroprocessed Fermented Sugars (SIP Fuels), Final Version (3.), Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants, Subcommittee D02.J0 on Aviation Fuels, Research Report D02-1776, ASTM International, West Conshohocken, PA, 15 June 2014. This is the third ASTM research report on a new annex for producing SAJF under D7566. The approved SIP (also referred to as Direct Sugar to Hydrocarbons DSHC) fuels pathway limits blending to 10% SAJF with conventional jet fuel since the fuel produced is essentially a single compound (farnesane) with 15 carbon atoms that falls within the conventional jet fuel specification. Emissions testing was performed on SaM146 and CFM56-5C4 jet engines and a 131-9 APU with the biofuel blended with Jet A-1. • Tests with the SaM146 showed no significant effect on CO, UHC, and NOx emissions of the SIP fuel compared to the reference Jet A-1. • In testing the CFM56 engine, emissions of CO were “identical for the SIP fuels and the reference Jet A-1.” • For NOx “… some slight difference among the SIP fuels and the reference Jet A-1 is discernible: for most power settings, emissions from the SIP fuels are below the emissions from the reference Jet A-1, whereas for cruise they are above.” • “… in conclusion, SIP fuels show similar, if not better, emission performances than the reference Jet A-1.” Shila, J., and Johnson, M., Estimation and Comparison of Particle Number Emission Factors for Petroleum-based and Camolina Biofuel Blends used in a Honeywell TFE-109 Turbofan Engine, AIAA SciTech Forum, 54th AIAA Aerospace Sciences Meeting, San Diego, California, 4-8 January 2016. • This study investigated the particulate matter emissions coming out of the TFE-109 turbofan engine exhaust to calculate the particle number concentration emissions factors (EIn) for the three different types of fuels. The fuels were provided by the Air Force. The Air Force Research Lab conducted the fuel analysis and blending of the fuels. The fuels were State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

27 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. categorized based on the volumetric percentage of Jet A content they contained. The first type of fuel was 100% Jet A fuel, the second batch contained 75% Jet A and 25% camelina biofuel, and the third fuel type contained 50% Jet A and 50% camelina biofuel. • These results are in agreement with other studies conducted in which the average EIn (in particles per kilogram of fuel) ranged between 3e16 and 1e17 for the AAFEX study, between 1e15 and 1e16 for the APEX study, and between 3e16 and 2e17 for the UNA-UNA study. The 75/25 blended fuel results were inconsistent with the two fuels in terms of range of emissions factors. Stratton, R.W., Wolfe, P.J., Hileman, J.I., Impact of Non-CO2 Combustion Effects on the Environmental Feasibility of Alternative Jet Fuels, Environmental Science & Technology 45 (24) 10736-10743, 22 November 2011. • The upper and lower bounds of NOX reduction were based on experimental results from Bester and Yates (2009), Bulzan et al. (2010), and Dewitt et al. (2008). The functional form of the distribution was chosen to reflect a conservative estimate within the bounds of experimental data. NOX emissions are strongly dependent on engine throttle setting, specific engine/combustor technology, and ambient temperature. • Soot reductions from SPK use in the PW308 varied from 95% at idle to 50% at 85% of full throttle; similarly, SPK fuel in the CFM56 led to a 98% reduction in soot at idle and a 70% reduction at 85% of full throttle. • The mode of the distribution is consistent with measurements from Bester and Yates (2009) and Bulzan et al. (2010), who measured average reductions of 85% and 90% in soot emissions over the throttle range of a CFM-56-2C1 engine using coal based F-T jet fuel from Sasol and natural gas based F-T jet fuel from Shell, respectively. • “The purely paraffinic nature and lack of sulfur in SPK fuels result in increased specific energy, decreased energy density, and changes to the emissions characteristics of CO2, H2O, soot, sulfates, and NOx.” • NOx emissions from the SPK fuel were 90-100% of those from conventional jet fuel. Timko, M.T., Herndon, S.C., de la Rosa Blanco, E., Wood, E.C., Yu, Z., Miake-Lye, R.C., Knighton, W.B., Shafer, L., DeWitt, M.J., Corporan, E., Combustion Products of Petroleum Jet Fuel, a Fischer-Tropsch Synthetic Fuel, and a Biomass Fatty Acid Methyl Ester Fuel for a Gas Turbine Engine, Combustion Science and Technology, 183: 1039-1068, 2011, 13 April 2011. This report presents combustion emissions data for a natural gas-derived Fischer-Tropsch alternative jet fuel both neat and blended 50/50 with Jet A-1 and both 20/80 and 40/60 blends of a fatty acid methyl ester (FAME) [FAME includes oxygenated compounds and does not meet the D7566 specification for SAJF] with Jet A-1. The emissions testing was performed using a CFM56-7 commercial jet engine. Emissions of NOx, CO, speciated VOC (including oxygenates, olefins, and aromatic compounds), and PM were measured. • “… the effects of alternative fuels on [emissions of] CO and HCHO [formaldehyde, a surrogate for UHC] are relatively modest.” • The lack of robust temperature-correction protocol for HCHO emissions and the sensitivity of HCHO emissions to fuel flow rate may obscure a modest decrease for alternative fuel combustion. • For FT fuel combustion, NOx emissions are reduced by 10% (100% FT fuel) and 5% (50% FT fuel blend) compared to Jet A. however, “… the difference [in NOx emissions] between Jet A and 50% FT fuel combustion is not statistically significant.” • “… replacing some or all of the Jet A-1 with the alternative fuels tends to reduce PM mass, number, and size.” Soot mass, particle number density, and size are reduced for combustion of alternative fuels when compared to Jet A. The PM reduction effect is most pronounced at low power and diminishes as power is increased. • “Overall, emissions performance improved or stayed the same when all or part of the Jet A-1 content was replaced by an alternative fuel.” • “For FT fuel combustion, NOx emissions are reduced by 10% (100% FT fuel) and 5% (50% FT blend) compared to Jet A.” State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

28 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. • “Combustion of alternative fuels and fuel blends modifies the VOC composition profile,” which can be divided into three parts: (1) hydrocarbons, (2) oxygenates (increased for combustion of alternative fuels), and (3) aromatics (reduced in proportion to decreasing Jet A-1 content of the fuel). Vander Wal, R., Bryg, V., Huang, C., Insights into the Combustion Chemistry Within a Gas-Turbine Driven Auxiliary Power Unit as a Function of Fuel Type and Power Level using Soot Nanostructure as a Tracer, Fuel 115 (2014) 282– 287. • Particulate emissions were collected from an auxiliary power unit (APU) directly upon TEM grids for particle characterization by HRTEM. Carbonaceous emissions from two fuels, a coal-based Fischer–Tropsch and standard JP-8 were compared, each at three power levels. Differences in soot nanostructure, specifically fullerenic content, reveal changes in the combustion chemistry with engine power level, as do differences in aggregate size between the two fuels. As inferred from the soot nanostructure, comparison between fuels demonstrates the impact of fuel structure upon soot formation chemistry. • The APU is a small gas-turbine engine, Honeywell Model GTCP85-98CK whose exhaust is mixed with bleed air and exhausted just before the wing spar. • Comparisons between the FT and JP-8 fuels provides further support in that for the same power level, soot from the JP-8 fuel contains less fullerenic nanostructure, reflecting its substantial aromatic content that accelerates soot formation and minimizes the impact of partial premixing. Differences in aggregate size between the two fuels at each power level are consistent with this interpretation. At each power larger aggregates, indicative of a locally higher fuel concentration is observed for the JP-8 fuel. Therein soot structure across length scales preserves a record of the gas phase species concentration and identity contributing to its formation and growth. This suggests nanostructure can be used as an in situ tracer of the early combustion chemistry within the engine. Wey, C, and Bulzan, D., Effects of Bio-Derived Fuels on Emissions and Performance Using a 9-Point Lean Direct Injection Low Emissions Concept, Proc. ASME Turbo Expo 2013, GT2013-94888. A 9-point lean direct low emissions combustor concept was utilized to evaluate gaseous emissions performance of two bio- derived alternative jet fuels and a JP-8 fuel for comparison. • The bio-derived jet fuels utilized for the testing included a Hydroprocessed Esters and Fatty Acids (HEFA) or sometimes termed Hydrotreated Renewable Jet (HRJ) fuel, and a fuel produced from direct fermentation of sugar called AMJ-710 from Amyris. • For the conditions evaluated in the present study, there were no significant differences in NOx emissions between the three fuels for the conditions tested for the 9-point LDI configuration. • At 350 and 250 psia, CO emissions do not show any significant differences between the three fuels. At 150 psia, CO emissions from the HRJ fuel were slightly lower at higher fuel/air ratios. • Combustion efficiencies were very high, greater than 99.9% for the operating ranges examined and again, no significant differences were found between the fuels. There were no significant differences in CO EI emissions between the various fuels and JP-8/alternative fuel blends. • Gaseous emissions measured using a 9-point LDI concept showed no significant differences between the fuels. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. All rights reserved.

29 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. 6. REFERENCES 1. Altaher, M., Andrews, G., and Li, H., PM Characteristics of Low NOx Combustor Burning Biodiesel and its Blends with Kerosene, Proceedings of ASME Turbo Expo 2013: Turbine Technical Conference and Exposition GT2013, June 3-7, 2013, San Antonio, Texas, USA 2. Anderson, B.E., et al., Alternative Aviation Fuel Experiment (AAFEX), NASA Project Report NSAS/TMI2011I217059, February 2011. 3. Anderson, B. NASA Langley Research Center, Alternative Fuel Effects on Contrails & Cruise Emissions (ACCESS-2) Flight Experiment, ACCESS Science and Implementation Teams, 09 January 2015. 4. ASTM D1655-16a, Standard Specification for Aviation Turbine Fuels, ASTM International, West Conshohocken, PA, 1 April 2016. 5. ASTM D7566-16b, Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons, ASTM International, West Conshohocken, PA, 1 July 2016. 6. Beyersdorf, A. J., Timko, M. T., Ziemba, L. D., Bulzan, D., Corporan, E., Herndon, S. C., Howard, R., Miake-Lye, R., Thornhill, K. L., Winstead, E., Wey, C., Yu, Z., and Anderson, B. E., Reductions in Aircraft Particulate Emissions due to the use of Fischer–Tropsch Fuels, Atmos. Chem. Phys., 14, 11–23, 2014. 7. Bhagwan, R., Habisreuther, P., Zarzalis, N., and Turrini, F., An Experimental Comparison of the Emissions Characteristics of Standard Jet A-1 and Synthetic Fuels, Flow Turbulence Combustion (2014) 92:865–884. 8. Biddle T., Pratt & Whitney Emissions Test to Determine the Effect of Sasol Fully Synthetic Jet-A Fuel on the Emissions of a Commercial Combustor, Southwest Research Institute, 2-007. 9. Blakey, S., Rye, L., Wilson, C.W., Aviation Gas Turbine Alternative Fuels: A Review, Proceedings of the Combustion Institute, 33 (2011), 2863-22885, 09 November 2010. 10. Boeing Company, UOP, U.S. Air Force Research Laboratory, Evaluation of Bio-Derived Synthetic Paraffinic Kerosenes (Bio-SPK), Report Version 5.0, Committee D02 on Petroleum Products and Lubricants, Subcommittee D02.J0.06 on Emerging Turbine Fuels, Research Report D02-1739, ASTM International, West Conshohocken, PA, 28 June 2011. 11. Brem, T.B., et al., Effects of Fuel Aromatic Content on Nonvolatile Particulate Emissions of an In-Production Aircraft Gas Turbine, Environmental Science & Technology2015, 49 (22), 13149-13157, 23 October 2015. 12. Cain, J., DeWitt, M., Blunck, D., Corporan, E., Striebich, R., Anneken, D., Klingshirn, C., Roquemore, W. M., and Vander Wall, R., Characterization of Gaseous and Particulate Emissions From a Turboshaft Engine Burning Conventional, Alternative, and Surrogate Fuels, Energy Fuels 2013, 27, 2290−2302. 13. Carter, N. A., Stratton, R.W., Bredehoeft, M.K., and Hileman, J.I., Energy and Environmental Viability of Select Alternative Jet Fuel Pathways, 47th AIAA/ASME, SAE, ASEE Joint Propulsion Conference & Exhibit, 31 July – 03 August 2011, San Diego, CA, AIAA 2011-5968. 14. Carter, N. A., Environmental and Economic Assessment of Microalgae-Derived Jet Fuel, Laboratory for Aviation and the Environment, Massachusetts Institute of Technology, June 2012. 15. Chan, T.W., Chishty, W. A., Canteenwalla, P., Buote, D., and Davidson, C.R., Characterization of Emissions From the Use of Alternative Aviation Fuels, Journal of Engineering for Gas Turbines and Power Journal of Engineering for Gas Turbines and Power, January 2016, Vol. 138 / 011506-1. 16. Chen, L. Zhang, Z. Lu, Y., Zhang, C., Zhang, X., Zhang, C., Roskilly, A. P., Experimental Study of the Gaseous and Particulate Matter Emissions from a Gas Turbine Combustor Burning Butyl Butyrate and Ethanol Blends, Applied Energy 195 (2017) 693–701. 17. Christie, S., D4.3 Emissions Report and Database of Systems Key Performance Parameters, ITAKA Collaborative Project, FP7-308807, 30 April 2015. 18. Christie, S., Lobo, P., Lee, D., Raper, D., Gas Turbine Engine Nonvolatile Particulate Matter Mass Emissions: Correlation with Smoke Number for Conventional and Alternative Fuel Blends, Environ. Sci. & Techn. 2017, 51, 988- 996. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

30 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. 19. Colket, M., Heyne, J., Rumizen, M., Gupta. M., Jardines, A., Edwards, T., Roquemore, W. M., Andac, G., Boehm, R., Zelina, J., Lovett, J., Condevaux, J., Bornstein, S., Rizk, N., Turner, D., Graves, C., Anand, M.S., An Overview of the National Jet Fuels Combustion Program, AIAA SciTech Forum 54th AIAA Aerospace Sciences Meeting, 4-8 January 2016, San Diego, California. 20. Corporan, E., DeWitt, M.J., Klingshirn, C.D., Anneken, D., Alternative Fuels Tests on a C-17 Aircraft: Emissions Characteristics, Air Force Research Laboratory, Interim Report, AFRL-RZ-WP-TR-2011-2004, Wright-Patterson Air Force Base, OH, December 2010. 21. Corporan, E., Edwards, T., Shafer, L., DeWitt, M.J., Klingshirn, C.D., Zabarnick, S., West, Z., Striebich, R., Graham, J., Klein, J., Chemical, Thermal Stability, Seal Swell, and Emissions Studies of Alternative Jet Fuels, Energy & Fuels, 2011, 25, 955-966, 2 March 2011. 22. Corporan, E., DeWitt, M.J., Klingshirn, C.D., Anneken, D., Shafer, L., Striebich, R., Comparison of Emissions Characteristics of Several Turbine Engines Burning Fischer-Tropsch and Hydroprocessed Esters and Fatty Acids Alternative Jet Fuels, Proceedings of ASME Turbo Expo 2012, Copenhagen, Denmark, 11-15 June 2012. 23. Daily, B., Ginestra, C., Reduced Emissions Via Synthesized Aromatic Kerosene, Virent briefing to ASCENT Seattle, WA, 13 October 2015. 24. Del Rosario, R., Koudelka, J., Wahls, R., Madavan, N., Bulzan, D., Alternative Aviation Fuel Experiment II (AAFEX II) Overview, 19 September 2012. 25. Donohoo, P. Scaling Air Quality Effects from Alternative Jet Fuel in Aircraft and Ground Support Equipment, M.Sc. Thesis, Massachusetts Institute of Technology, Cambridge, MA, 2010. 26. Edwards, T., Meyer, D., Johnston, G., McCall, M., Rumizen, M., Wright, M., Evaluation of Alcohol to Jet Synthetic Paraffinic Kerosenes (ATJ-SPK), Report Version (1.10), Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants, Subcommittee D02.J0 on Aviation Fuels, Research Report D02-1828, ASTM International, West Conshohocken, PA, 1 April 2016. 27. Hendricks, R.C., Bushnell, D., Particulate Emissions Hazards Associated with Fueling Heat Engines, International Journal of Rotating Machinery, Volume 2011, Article ID 415296, 18 March 2011. 28. Hermann, F, Comparison of Combustion Properties Between a Synthetic Jet Fuel and Conventional Jet A-1, In: Proceedings of ASME Turbo Expo. Nevada; 2005. GT2005-68540. 29. Huang, C.J., Vander Wal, R.L., Effect of Soot Structure Evolution from Commercial Jet Engine Burning Petroleum Based JP-8 and Synthetic HRJ and FT Fuels, Energy and Fuels, 2013, 27, 4946-4958, 24 July, 2013. 30. ICAO Airport Air Quality Guidance, first edition, International Civil Aviation Organization (ICAO), 999 University Street, Montreal, Quebec CA H3C5H. 31. Koenig, J.Q., Health Effects of Ambient air Pollution, How safe is the air we breathe, Kluwer Academic 2000. 32. Leikauf, G. D., Hazardous Air Pollutants and Asthma, Environmental Health Perspective, 110 (suppl 4), 505-526, 2002. 33. Lew, L., Biddle, T., United Technologies Corporation, P&WC Engine Test and Combustor Rig Test Performed on 20 Percent Amyris Farnesane/Jet A Blend, for the Continuous Energy, Emissions and Noise (CLEEN) Program, East Hartford, CT, 16 April 2014. 34. Li, H, et al., Influence of Fuel Composition, Engine Power, and Operation Mode on Exhaust Gas Particulate Size Distribution and Gaseous Emissions from a Gas Turbine Engine, Proc. ASME Turbo Expo 2013, GT2013-94854. 35. Li, H., Altaher, M., Wilson, C., Blakey, S., Chung, W., Rye, L., Quantification of Aldehydes Emissions from Alternative and Renewable Aviation Fuels using a Gas Turbine Engine, Atmospheric Environment 84 (2014) 373-379. 36. Lobo, P., Hagen, D., Whitefield, P., Comparison of PM Emissions from a Commercial Jet Engine Burning Conventional, Biomass, and Fischer-Tropsch Fuels, Environmental Science & Technology, 1 November 2011. 37. Lobo, P., Christie, S., Khandelwal, B., Blakey, S.G., Raper, D.W., Evaluation of Non-volatile Particulate Matter Emission Characteristics of an Aircraft Auxiliary Power Unit with Varying Alternative Jet Fuel Blend Ratios, Energy and Fuels, 2015, 29, 7705-7711, 16 October, 2015. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

31 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. 38. Moore, R., Shook, M,. Beyersdorf, A., Corr, C., Herndon, S., Knighton, W., Miake-Lye, R., Thornhill, K., Winstead, E., Yu, Z., Ziemba, L., Anderson, B., Influence of Jet Fuel Composition on Aircraft Engine Emissions: A Synthesis of Aerosol Emissions Data from the NASA APEX, AAFEX, and ACCESS Missions, Energy and Fuels, 2015, 29, 2591- 2600, 25 February, 2015. 39. Moore, R., et al., Biofuel Blending Reduces PM Emissions from Aircraft Engines at Cruise Conditions, Nature 21420, doi:10.1038. 40. Moses, C.A, Comparative Evaluation of Semi-Synthetic Jet Fuels (FT-SPK), Final Report, Coordinating Research Council, Inc., Universal Technology Corporation, CRC project No. AVI 2I04a, Alpharetta, GA September 2008. 41. Moses, C., Evaluation of Synthesized Aromatics Co-Produced with Iso-Paraffinic Kerosene for the Production of Semi-Synthetic Jet Fuel (SKA), Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants, Subcommittee D02.J0 on Aviation Fuels, Section D02.J0.06 on Emerging Turbine Fuels, Research Report D02-1810, ASTM International, West Conshohocken, PA, 1 November 2015. 42. Rahmes, T.F., Kinder, J.D., Henry, T.M., Crenfeldt, G.,LeDuc, G.F., Zombanakis, G.P., Abe, Y., Lambert, D.M., Lewis, C., Juenger, J.A., Andac, M.G., Reilly, K.R., Holmgren, J.R., McCall, M.J., Bozzano, A.G., Sustainable Bio-Derived Synthetic Paraffinic Kerosene (Bio-SPK) Jet Fuel Flights and Engine Tests Program Results, 9th AIAA Aviation Technology, integration and operations conference, AIAA 2009-7002, Sept, 2009. 43. Roland, O., Garcia, F., TOTAL New Energies, Amyris, Inc., U.S. Air Force Research Laboratory, Evaluation of Synthesized Iso-Paraffins Produced from Hydroprocessed Fermented Sugars (SIP Fuels), Final Version (3.), Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants, Subcommittee D02.J0 on Aviation Fuels, Research Report D02-1776, ASTM International, West Conshohocken, PA, 15 June 2014. 44. Shila, Jacob J., and Johnson, Mary E., Estimation and Comparison of Particle Number Emission Factors for Petroleum-based and Camolina Biofuel Blends used in a Honeywell TFE-109 Turbofan Engine, AIAA SciTech Forum, 54th AIAA Aerospace Sciences Meeting, San Diego, California, 4-8 January 2016. 45. Shouse, D.T., Neuroth, C., Hendricks, R.C., Lynch, A., Frayne, C.W., Stutrud, J.S., Corporan, E., Hankins, T. Alternate- fueled Combustor-sector Performance: Part A: Combustor Performance Part B: Combustor Emissions, 2010. ISROMAC13-2010-49. 46. Speth, R.R., Rojo, C., Malina, R., Barrett, S.R.H., Black Carbon Emissions Reductions from Combustion of Alternative Jet Fuels, Atmospheric Environment 105 (2015) 37-42, 19 January 2015. 47. Stratton, R.W., Wolfe, P.J., Hileman, J.I., Impact of Non-CO2 Combustion Effects on the Environmental Feasibility of Alternative Jet Fuels, Environmental Science & Technology 45 (24) 10736-10743, 22 November 2011. 48. Timko, M.T., Herndon, S.C., de la Rosa Blanco, E., Wood, E.C., Yu, Z., Miake-Lye, R.C., Knighton, W.B., Shafer, L., DeWitt, M.J., Corporan, E., Combustion Products of Petroleum Jet Fuel, a Fischer-Tropsch Synthetic Fuel, and a Biomass Fatty Acid Methyl Ester Fuel for a Gas Turbine Engine, Combustion Science and Technology, 183: 1039- 1068, 2011, 13 April 2011. 49. Vander Wal, R., Bryg, V., Huang, C., Insights into the Combustion Chemistry Within a Gas-Turbine Driven Auxiliary Power Unit as a Function of Fuel Type and Power Level using Soot Nanostructure as a Tracer, Fuel 115 (2014) 282–287. 50. Wey, C, and D. Bulzan, Effects of Bio-Derived Fuels on Emissions and Performance Using a 9-Point Lean Direct Injection Low Emissions Concept, Proc. ASME Turbo Expo 2013, GT2013-94888. 51. Winchester, N., Malina, R., Staples, M.D., Barrett, S.R.H., The Impact of Advanced Biofuels on Aviation Emissions and Operations in the U.S., Energy Economics 49 (2015) 482-491, 8 April 2015. State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

32 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. 7. APPENDIX This appendix includes tables summarizing the impacts of alternative fuels on the emissions of SOx, PM2.5, CO, UHC, NOx, and HAP. Alt Fuel Ref Fuel Engine Impact Ref # FT GTL JP-8 CFM56-2C1 EI_SO2  90% for pure FT, and  intermodiatly for blends. 6 HEFA JP-8 F117-PW-100 SO2  50% for 50% blend. 20 Table A.1: Alternative Fuel Impact on SOx Emissions Alt Fuel Ref Fuel Engine Impact Ref # ATJ-SPK JP-8 PW615F Smoke # & P. no Δ 26 Beef Tallow JP-8 F117-PW-100 = PW2000 nvPM N  63% at idle; nvPM GMD  10-15%; EIm  50- 70% at 63% power; SN no Δ. 20 Beef Tallow JP-9 T63-A-701 Soot  significantly. 21 Camelina Jet A TFE-109 Honeywell nvPM EIn  at power settings of 10% and 30%. 44 Camelina JP-10 T63-A-702 Soot  significantly. 21 CH-SKA Jet A2 CF-700-2D-2 GE BC mass  38-50% 15 Fats & Grease JP-11 T63-A-703 Soot  significantly. 21 FT GTL Jet A1 CFM56-7B EIn , EIm  36 FT GTL Jet A1 CFM56-7 nvPM N & Mass & GMD  48 FT GTL JP-8 CFM56-2C1 nvPM Mass  86% averaged over power for pure FT,  66% for blended FT/JP-8, largest reduction at idle; EI_N  95% for pure FT and  85% for blends 6 FT GTL JP-8 CFM-56-2C EIn  varied monotonically with power: factor 200 at idle, factor 4 at max thrust; EIm  factor 30 at 45-65% power, factor 7 at 85% power 2 Table A.2: Alternative Fuel Impact on PM2.5 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

33 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Alt Fuel Ref Fuel Engine Impact Ref # FT GTL JP-8 T63-A-700 Soot  significantly. 21 FT GTL JP-8 CFM56-7 EIn  up to 80% 22 FT GTL JP-8 CFM56-2 EIn  up to 80% 22 FT GTL JP-8 PW308 EIn  up to 35% 22 FT_AAFEX JP-8 CFM56-2-C nvPM  19 FT-SPK Jet A1 CF-700-2D-2 GE nvPM N  70-95%; BC mass  70-95%. 15 HEFA JP-8 CFM56-8 EIn  up to 80% 22 HEFA JP-8 CFM56-3 EIn  up to 80% 22 HEFA JP-8 PW309 EIn  up to 35% 22 HEFA, SAK Jet A TRS-18 Microturbo nvPM N & Mass  35-70% 23 HEFA-SPK Jet A3 CF-700-2D-2 GE nvPM N  40-60%; BC mass 58-82% 15 HRJ- AAFEX JP-9 CFM56-2-C nvPM  19 SPK JP-8 Allison T63-A-700 nvPM N, Mass, and GMD  12 SPK JP-8 PW308 Soot  95% at idle & 50% at 85% power 25 SPK JP-8 CFM56 Soot  98% at idle & 70% at 85% power 25 UCO HEFA Jet A GTCP85- 129 Garrett Honeywell APU nvPM N & Mass & GMD  18 Continued Table A.2: Alternative Fuel Impact on PM2.5 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

34 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Alt Fuel Ref Fuel Engine Impact Ref # SPK JP-8 Allison T63-A-700 CO  10-20% except no Δ for the m-xylene/C12 blend 12 Sasol FSJF Jet A CO  19% in LTO cycle 8 FT-SPK Jet A1 CO  when lean &  when rich 28 FT-GTL JP-8 Combustor sector CO  45 FT_AAFEX JP-8 CFM56-2-C Minor Δ in gaseous emissions 19 HRJ- AAFEX JP-9 CFM56-2-C Minor Δ in gaseous emissions 19 Bio fuel RP-3 av kero Combustor rig CO  16 Beef Tallow JP-8 F117-PW-100 = PW2000 CO  20-40% 20 FT GTL JP-8 CFM-56-2C CO  9% 2 ATJ-SPK JP-8 AE 3007 combustor CO  slightly at low power 26 ATJ-SPK JP-8 TFE34 CO  slightly at low power 26 ATJ-SPK JP-8 PW615F 0 26 ATJ-SPK JP-8 TPE331- 10YGD CO  slightly at low power 26 Beef Tallow JP-9 T63-A-701 CO  10-25% 21 Bio-SPK Jet A CFM56-7B CO  5-9% 10 Bio-SPK JP-8 TPE331-10 CO no Δ except slightly  at low power 10 Bio-SPK JP-8 TFE731-5 CO  ~2% at idle 10 Camelina JP-10 T63-A-702 CO  10-25% 21 DSHC Jet A1 SaM146 0 43 DSHC Jet A1 CFM56-5C4 0 43 Table A.3: Alternative Fuel Impact on CO State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

35 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Alt Fuel Ref Fuel Engine Impact Ref # Fats & Grease JP-11 T63-A-703 CO  10-25% 21 FT GTL Jet A1 CFM56-7 Modest changes in CO 48 FT GTL JP-8 T63-A-700 CO  10-25% 21 FT GTL JP-8 CFM56-7 Normalized C. 0.8-1.0. 22 FT GTL JP-8 CFM56-2 Normalized C. 0.8-1.0. 22 FT GTL JP-8 F117 Normalized C. 0.8-1.0. 22 FT GTL JP-8 TF33 Normalized C. 0.8-1.0. 22 FT GTL JP-8 PW308 Normalized C. 0.8-1.0. 22 HEFA JP-8 CFM56-8 Normalized C. 0.8-1.0. 22 HEFA JP-8 CFM56-3 Normalized C. 0.8-1.0. 22 HEFA JP-8 F118 Normalized C. 0.8-1.0. 22 HEFA JP-8 TF34 Normalized C. 0.8-1.0. 22 HEFA JP-8 PW309 Normalized C. 0.8-1.0. 22 SPK Normalized: CO 0.74-0.87 for 100% alt fuel. Normalized: CO 0.83-0.91 for 50% blend. 13 Continued Table A.3: Alternative Fuel Impact on CO State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

36 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Alt Fuel Ref Fuel Engine Impact Ref # ATJ-SPK JP-8 AE 3007 combustor UHC  slightly at low power 26 ATJ-SPK JP-8 TFE34 UHC  slightly at low power 26 ATJ-SPK JP-8 TPE331- 10YGD UHC  slightly at low power 26 Beef Tallow JP-9 T63-A-701 UHC  20-30% 21 Bio fuel RP-3 aviation kerosene Combustor rig UHC  by up to 61%. Increasing ethanol content  UHC. 16 Bio-SPK JP-8 TPE331-10 UHC  5-20% at lowest power 10 Bio-SPK JP-8 TFE731-5 UHC  ~2% at idle 10 Camelina JP-10 T63-A-702 UHC  20-30% 21 Fats & Grease JP-11 T63-A-703 UHC  20-30% 21 FT GTL JP-8 CFM56-2C1 EI_UHC  40% for pure FT, and  intermodiatly for blends. 6 FT GTL JP-8 CFM-56-2C THC  22%. 2 FT GTL JP-8 T63-A-700 UHC  20-30% 21 FT_AAFEX JP-8 CFM56-2-C Minor Δ in gaseous emissions 19 HRJ- AAFEX JP-9 CFM56-2-C Minor Δ in gaseous emissions 19 Sasol FSJF Jet A UHC no Δ at idle. 8 SPK Normalized: UHC 0.68-0.76 for 100% alt fuel. Normalized: UHC 0.76-0.86 for 50% blend. 13 UCO SPK Jet A1 GTCP85 Garret Honeywell APU 0 17 Table A.4: Alternative Fuel Impact on UHC State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

37 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Alt Fuel Ref Fuel Engine Impact Ref # AMJ JP-8 9 pt lean direct low emissions combustor 0 50 ATJ-SPK JP-8 AE 3007 combustor 0 26 ATJ-SPK JP-8 TFE34 0 26 ATJ-SPK JP-8 PW615F 0 26 ATJ-SPK JP-8 TPE331- 10YGD 0 26 Beef Tallow JP-8 F117-PW-100 = PW2000 0 20 Beef Tallow JP-9 T63-A-701 0 21 Bio fuel RP-3 av kero Combustor rig NOx  by up to 70%. Increasing ethanol content  NOx. 16 Bio-SPK Jet A CFM56-7B - (1-5%) 42 Bio-SPK Jet A CFM56-7B NOx  1-5% 10 Bio-SPK JP-8 TPE331-10 0 10 Bio-SPK JP-8 TFE731-5 NOx  3.5% at cruise condition 10 Camelina JP-10 T63-A-702 0 21 CH-SKA Jet A2 CF-700- 2D-2 General Electric NOx  7-25% 45 DSHC Jet A1 SaM146 0 43 DSHC Jet A1 CFM56-5C4 NO. slightly  except slightly  at cruise 43 DSHC Jet A1 131-9 APU NO. slightly  except slightly  at cruise 43 FAE Jet A1 MK113 APU Artouste Slightly  34 Fats & Grease JP-11 T63-A-703 0 21 FT GTL Jet A1 CFM56-7 NOx  10% for 100% FT and  5% for 50% blend 48 Table A.5: Alternative Fuel Impact on NOx State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

38 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Alt Fuel Ref Fuel Engine Impact Ref # FT GTL JP-8 CFM56-2 0 22 FT GTL JP-8 F117 0 22 FT GTL JP-8 TF33 0 22 FT GTL JP-8 PW308 0 22 FT GTL (100%) Jet A CFM56-7B -10% 48 FT GTL (50%) Jet A CFM56-7B -5% 48 FT_AAFEX JP-8 CFM56-2-C Minor Δ in NOx 19 FT-GTL JP-8 Combustor sector NOx  when lean &  when rich. 45 FT-SPK Jet A1 Tubular combustor NOx  at low pressure; no Δ at high pressure. 7 FT-SPK Jet A1 NOx  always except when rich at high inlet air temp. 28 HEFA Jet A1 MK113 APU Artouste  except slightly  at idle 34 HEFA JP-8 9 pt lean direct low emissions combustor 0 50 HEFA JP-8 CFM56-8 0 22 HEFA JP-8 CFM56-3 0 22 HEFA JP-8 F118 0 22 HEFA JP-8 TF34 0 22 HEFA JP-8 PW309 0 22 HRJ- AAFEX JP-9 CFM56-2-C Minor Δ in NOx 19 HVO Jet A JT9D-7R4G2 0 42 Sasol FSJF Jet A NOx  4% in LTO cycle 8 Continued Table A.5: Alternative Fuel Impact on NOx State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

39 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Alt Fuel Ref Fuel Engine Impact Ref # SPK Normalized: NOx 0.91-1.01 13 UCO SPK Jet A1 GTCP85 Garret Honeywell APU 0 17 Continued Table A.5: Alternative Fuel Impact on NOx State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

40 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Alt Fuel Ref Fuel Engine Impact Ref # Beef Tallow JP-8 F117-PW-100 = PW2000 HAP  20 Beef Tallow JP-9 T63-A-701 Formaldehyde no Δ 21 Camelina JP-10 T63-A-702 Formaldehyde no Δ 21 FAE Jet A3 MK113 APU Artouste Formaldehyde  at idle,  at high power. 35 Fats & Grease JP-11 T63-A-703 Formaldehyde no Δ 21 FT GTL Jet A1 MK113 APU Artouste Formaldehyde  30% Acrolein  36-64% at idle; Formaldehyde  by factor 2-3 at high power. 35 FT GTL Jet A1 CFM56-7 Modest changes in HCHO 48 FT GTL JP-8 CFM-56-2C HAPS  significantly, e.g. EI-benzene  factor 5 at idle. 2 FT GTL JP-8 T63-A-700 Formaldehyde no Δ 21 FT GTL JP-8 CFM56-7 0 22 FT GTL JP-8 CFM56-2 0 22 FT GTL JP-8 F117 0 22 FT GTL JP-8 TF33 0 22 FT GTL JP-8 PW308 0 22 FT_AAFEX JP-8 CFM56-2-C Minor Δ in gaseous emissions 19 HEFA Jet A2 MK113 APU Artouste No Δ in aldehyde emissions. 35 HEFA JP-8 CFM56-8 0 22 HEFA JP-8 CFM56-3 0 22 HEFA JP-8 F118 0 22 HEFA JP-8 TF34 0 22 HEFA JP-8 PW309 0 22 Table A.6: Alternative Fuel Impact on HAP State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

40 State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Copyright National Academy of Sciences. All rights reserved. Alt Fuel Ref Fuel Engine Impact Ref # Beef Tallow JP-8 F117-PW-100 = PW2000 HAP  20 Beef Tallow JP-9 T63-A-701 Formaldehyde no Δ 21 Camelina JP-10 T63-A-702 Formaldehyde no Δ 21 FAE Jet A3 MK113 APU Artouste Formaldehyde  at idle,  at high power. 35 Fats & Grease JP-11 T63-A-703 Formaldehyde no Δ 21 FT GTL Jet A1 MK113 APU Artouste Formaldehyde  30% Acrolein  36-64% at idle; Formaldehyde  by factor 2-3 at high power. 35 FT GTL Jet A1 CFM56-7 Modest changes in HCHO 48 FT GTL JP-8 CFM-56-2C HAPS  significantly, e.g. EI-benzene  factor 5 at idle. 2 FT GTL JP-8 T63-A-700 Formaldehyde no Δ 21 FT GTL JP-8 CFM56-7 0 22 FT GTL JP-8 CFM56-2 0 22 FT GTL JP-8 F117 0 22 FT GTL JP-8 TF33 0 22 FT GTL JP-8 PW308 0 22 FT_AAFEX JP-8 CFM56-2-C Minor Δ in gaseous emissions 19 HEFA Jet A2 MK113 APU Artouste No Δ in aldehyde emissions. 35 HEFA JP-8 CFM56-8 0 22 HEFA JP-8 CFM56-3 0 22 HEFA JP-8 F118 0 22 HEFA JP-8 TF34 0 22 HEFA JP-8 PW309 0 22 Table A.6: Alternative Fuel Impact on HAP State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels opyright ational cade y of ciences. ll rights reserved.

State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

TRB's Airport Cooperative Research Program (ACRP) Web-Only Document 35: State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels captures the current status of knowledge to reduce carbon dioxide emissions using sustainable alternative jet fuels (SAJF). In the process of reducing SAJF, emissions of other pollutants may also be reduced, which could be significantly beneficial to airports. These reductions are not yet well defined, leaving airports unable to realize what may be substantial benefits. The research team analyzed the published technical literature to validate that SAJF use reduces air pollutant emissions and does not cause any air pollutant emissions to increase.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!