3

Engine Systems and Fuels

INTRODUCTION

Heavy-duty truck engines are central to all aspects of the 21st Century Truck Partnership (21CTP) vision: improved thermal efficiency, reduced oil dependency, low-exhaust emissions, low cost, and improved safety are aspects of that vision. Although diesel engines used in most trucks are the most efficient on-road transportation power plants available today, with diesel engines only approximately 42 percent of the fuel energy is converted to mechanical work, resulting in a loss of the energy input by means of the fuel of approximately 58 percent (DOE, 2010a). Additional improvements in the thermal efficiency of diesel and gasoline engines are still possible. However, there are thermodynamic limitations, which means that only a modest portion of the 58 percent of energy that is lost today can ever be recovered. In addition to petroleum-based fuels, these engines can be powered by nonpetroleum fuels from a number of feedstocks. The engine, together with the fuel characteristics and exhaust emission control devices, governs the level of exhaust emissions so critical for compliance with regulations, environmental impact, and public perception. The engine is critical to the safety of the heavy vehicle because it provides braking power, as well as adequate power for the vehicle to blend with traffic. This chapter covers engine programs, fuel programs, aftertreatment systems, high-temperature materials, and health concerns related to emissions from diesel engines.

Several members of the 21CTP are global companies, and they bring to the Partnership the perspective of technologies used in markets around the world. The committee also was given a presentation on a joint Department of Energy (DOE)/Swedish Ministry of Energy research project that combined U.S. and European technology.

ENGINE PROGRAMS: STATE OF TECHNOLOGY

Diesel engines derive their efficiency from high-efficiency thermodynamic processes, fuel with a high heating value, and minimal mechanical losses. These engines achieve their efficiency by means of a high compression (expansion) ratio, high rates of combustion under overall lean fuel conditions, and the use of air-to-fuel ratio (instead of throttling) for managing load control, thus avoiding part-load pumping losses. Turbocharging increases engine power density and recovers some of the exhaust energy. Diesel engines operate at relatively low speeds, which reduce mechanical friction losses, and high power density is achieved primarily through high brake mean effective pressure (BMEP).1

Owing to its low fuel consumption, reliability, and low life-cycle cost, the diesel engine has continued to be the preferred power source for commercial vehicles, urban buses, and military vehicles worldwide. The cost of complying with emissions regulations for traditional diesel combustion has given rise to reconsideration of alternative power plants such as heavy-duty spark-ignition engines, and gasoline engines have even regained market share in Class 6 trucks (DOE, 2011a; NRC, 2010). High worldwide demand for diesel fuels has driven their price above gasoline in the United States, furthering this trend. In addition, U.S. national average diesel fuel taxes were 5 cents per gallon higher than for gasoline in January 2011, as reported by the American Petroleum Institute.

Modern highway truck diesel engine brake thermal efficiency (BTE) peaks at about 42 percent, compared to 33 percent for commercial gasoline, spark-ignition engines. This 42 percent peak efficiency represents significant improvement since the 1970s when highway diesel BTE peaked around 35 percent. Key elements for achieving a BTE of 50 percent have already been demonstrated in test laboratories, and demonstration is expected within the next few years in research vehicles meeting emissions standards.

_____________________

1 The brake mean effective pressure is the ratio of the shaft work leaving the engine to the displacement of the engine. This ratio is expressed in units of pressure, hence the name. BMEP is a useful metric in that it assesses the work output per unit of engine displacement, so it can be used to compare the performance of engines of different displacements.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 27
3 Engine Systems and Fuels INTRODUCTION and minimal mechanical losses. These engines achieve their efficiency by means of a high compression (expansion) ratio, Heavy-duty truck engines are central to all aspects of the high rates of combustion under overall lean fuel conditions, 21st Century Truck Partnership (21CTP) vision: improved and the use of air-to-fuel ratio (instead of throttling) for thermal efficiency, reduced oil dependency, low-exhaust managing load control, thus avoiding part-load pumping emissions, low cost, and improved safety are aspects of that losses. Turbocharging increases engine power density and vision. Although diesel engines used in most trucks are the recovers some of the exhaust energy. Diesel engines operate most efficient on-road transportation power plants available at relatively low speeds, which reduce mechanical friction today, with diesel engines only approximately 42 percent of losses, and high power density is achieved primarily through the fuel energy is converted to mechanical work, resulting in high brake mean effective pressure (BMEP).1 a loss of the energy input by means of the fuel of approxi- Owing to its low fuel consumption, reliability, and low mately 58 percent (DOE, 2010a). Additional improvements life-cycle cost, the diesel engine has continued to be the pre- in the thermal efficiency of diesel and gasoline engines are ferred power source for commercial vehicles, urban buses, still possible. However, there are thermodynamic limitations, and military vehicles worldwide. The cost of complying with which means that only a modest portion of the 58 percent of emissions regulations for traditional diesel combustion has energy that is lost today can ever be recovered. In addition given rise to reconsideration of alternative power plants such to petroleum-based fuels, these engines can be powered by as heavy-duty spark-ignition engines, and gasoline engines nonpetroleum fuels from a number of feedstocks. The engine, have even regained market share in Class 6 trucks (DOE, together with the fuel characteristics and exhaust emission 2011a; NRC, 2010). High worldwide demand for diesel fuels control devices, governs the level of exhaust emissions so has driven their price above gasoline in the United States, fur- critical for compliance with regulations, environmental thering this trend. In addition, U.S. national average diesel fuel impact, and public perception. The engine is critical to the taxes were 5 cents per gallon higher than for gasoline in Janu- safety of the heavy vehicle because it provides braking power, ary 2011, as reported by the American Petroleum Institute. as well as adequate power for the vehicle to blend with traffic. Modern highway truck diesel engine brake thermal effi- This chapter covers engine programs, fuel programs, after- ciency (BTE) peaks at about 42 percent, compared to 33 treatment systems, high-temperature materials, and health percent for commercial gasoline, spark-ignition engines. concerns related to emissions from diesel engines. T his 42 percent peak efficiency represents significant Several members of the 21CTP are global companies, and improvement since the 1970s when highway diesel BTE they bring to the Partnership the perspective of technologies peaked around 35 percent. Key elements for achieving a used in markets around the world. The committee also was BTE of 50 percent have already been demonstrated in test given a presentation on a joint Department of Energy (DOE)/ laboratories, and demonstration is expected within the next Swedish Ministry of Energy research project that combined few years in research vehicles meeting emissions standards. U.S. and European technology. 1 The brake mean effective pressure is the ratio of the shaft work leaving ENGINE PROGRAMS: STATE OF TECHNOLOGY the engine to the displacement of the engine. This ratio is expressed in units of pressure, hence the name. BMEP is a useful metric in that it assesses the Diesel engines derive their efficiency from high-efficiency work output per unit of engine displacement, so it can be used to compare thermodynamic processes, fuel with a high heating value, the performance of engines of different displacements. 27

OCR for page 27
28 REVIEW OF THE 21ST CENTURY TRUCK PARTNERSHIP, SECOND REPORT the use of DPFs and other types of exhaust aftertreatment Most advances in thermal efficiency will be achieved through (NRC, 2008). continued improvements in combustion, air handling, fuel For 2010, NOx emissions standards were lowered another injection equipment, and other subsystems. In addition, an 83 percent to 0.20 g/bhp-h NOx + HC, along with 0.01 g/bhp-h effective exhaust heat recovery system may be necessary for PM. These standards have been met by most engine original achieving 50 percent BTE. However, the design of a waste equipment manufacturers (OEMs) by a combination of cooled heat recovery (WHR) system must take into account the tem- exhaust gas recirculation (EGR) and selective catalytic reduc- perature requirements of exhaust emission control devices as tion (SCR) for NOx control and an actively regenerated DPF well as considerations such as weight, space, cost, reliability, for particulate control. Meeting the requirements of 2010 and durability. In order to be commercially viable, the WHR exhaust emissions regulations required significant in-cylinder system needs to last for the life of the engine, which carries control, high-performing aftertreatment for NOx and PM sys- an emissions warranty of 435,000 miles, but typically has tems, and engine thermal management that includes a degree a design life of 600,000 to 1 million miles. The 55 percent of control over exhaust mass flow rate, exhaust temperature, BTE stretch goal will require the research and development and exhaust oxygen. Thermal management, an essential ele- (R&D) of technologies discussed below in this chapter and ment in the integration of engine and aftertreatment, allows should include comparable BTE improvements over the both the DPF and the SCR to operate at peak efficiency over entire engine operating map, especially for those conditions a wide range of duty cycles. In contrast to most manufactur- used in a duty-cycle-weighted BTE. ers, which use SCR for NOx control, Navistar is planning to achieve the NOx standard with an EGR-only system and the Exhaust Emissions PM standard with a DPF (Navistar, 2010). Substantial effort across the industry went into the design Exhaust emissions of diesel engines have been regulated of systems for storing and metering urea on the vehicle; these since 1973 by the California Air Resources Board (CARB) systems are required to support SCR systems. Considerations and since 1974 by the U.S. Environmental Protection Agency of freeze protection, contamination, labeling, and stability (EPA). After 1974, diesel engine manufacturers achieved had to be accounted for. In addition, the infrastructure for remarkable reductions in oxides of nitrogen (NOx) (~99 per- distributing and dispensing urea at refueling outlets had to be cent) and particulate matter (PM) (99 percent) emissions by developed. The industry adopted the name of Diesel Exhaust modifying their engines and adding aftertreatment devices. Fluid (DEF) for the aqueous urea solution. It was found that Through 2006 heavy-duty diesel engines were certified at 2.5 there is an optimum balance between in-cylinder control of g/bhp-h of NOx + HC and 0.10 g/bhp-h PM (<0.05 g/bhp-h NOx and PM and aftertreatment control of NOx and PM. The for transit buses). In 2007 the regulations allowed a phase-in of sales-averaged NOx at approximately 1.2 g/bhp-h2 and PM primary parameter determining this optimum balance is the operating cost, driven by both fuel consumption and DEF at 0.01 g/bhp-h (DOE, 2006). consumption. Fuel consumption has been affected by some of Compliance with the 2007-2010 federal emissions stan- these emission control strategies, such as fuel used to regener- dards is perhaps the strongest example of progress by diesel ate particulate filters and DEF usage for the SCR system. engine manufacturers since the National Research Council Another key enabling system technology is high-pressure (NRC) Phase 1 review of the 21CTP in 2007 (NRC, 2008). common rail fuel systems with high-pressure capabilities Until 2007, exhaust aftertreatment had not been required or exceeding 2,400 bar and allowing multiple injections per cycle. utilized to meet emissions standards for heavy-duty diesels In addition, advancements in turbomachinery have resulted in (except for limited use of oxidation catalysts on buses and variable-geometry turbochargers, the use of multiple turbo- medium-sized trucks). The 2007-2010 regulations were chargers (in series and parallel) with aftercooling and inter- intended by the EPA to be “aftertreatment-forcing.” After- cooling, and turbocompounding. The turbomachinery serves treatment technologies for PM were necessary in 2007, several purposes in engine performance and emissions control, and all new truck heavy-duty diesel engines were equipped including airflow for high BMEP and transient response, EGR with diesel particulate filters (DPFs). Catalyst-based DPFs delivery and control, enhanced engine braking, and exhaust used with ultra-low-sulfur diesel fuel (<15 parts per mil- thermal management. EGR systems were introduced in 2002 lion [ppm]) achieve PM reductions in excess of 90 percent and have mainly been high-pressure loop with cooling by from 2006 levels. In October 2006, ultra-low sulfur diesel means of the engine coolant. Some low-pressure loop EGR sys- fuel became the mandatory on-highway fuel, thus enabling tems have also been introduced to the market. The first stage of implementation of on-board diagnostics (OBD) was completed on heavy-duty 2010 engines with a second stage in 2013. 2 The NO and nonmethane hydrocarbon (NMHC) standards were phased x As discussed in DOE (2006), engine controls deserve in for diesel engines between 2007 and 2010. The phase-in was on a percent- of-sales basis: 50 percent from 2007 to 2009 and 100 percent in 2010. In mention here, because historically, controls requirements 2007, most manufacturers opted to meet a Family Emission Limit (FEL) for diesel engines have lagged those for gasoline engines in around 1.2 to 1.5 g/bhp-hr NOx for most of their engines (average of 0.2 g/ passenger cars. For the truck diesel engine, controls were bhp-h NOx standard for 2010 and about 2.2 g/bhp-h NOx portion of the 2.5 primarily limited to one or two degrees of freedom (i.e., g/bhp-h NMHC + NOx standard for 2006).

OCR for page 27
29 ENGINE SYSTEMS AND FUELS fuel injection delivery and timing). The future controls by the engine at its best operating point. In general, peak effi- requirements in the heavy-duty diesel engine environment ciency occurs at relatively low speed and high load. As shown was realized with the introduction of EGR and the ongo- later in this section, the goal of a 50 percent peak BTE demon- ing implementation of more sophisticated multipulse fuel stration by 2010 was not met, but the technologies required to injection systems and strategies. With the introduction of achieve this goal have been demonstrated successfully. single- and multistage exhaust aftertreatment systems in The DOE has now revised the goal to require 50 percent 2007 and 2010 and the continuing progress of multimode BTE at a load representative of over-the-road vehicle cruise combustion toward production feasibility, coupled with leg- conditions by 2015. This change was recommended in the islated or customer-demanded expansion of onboard sensing NRC Phase 1 report (NRC, 2008). The actual speed and load and diagnostic features, the minimum required capability point are not defined by the DOE in its goal statements, but of heavy-duty control systems hardware and software has in the SuperTruck projects (see Chapter 8 in this report), 65 increased as much as several orders of magnitude. miles per hour (mph) level road cruise is established as the At present there is no expectation that new regulations operating point for 50 percent BTE. The committee believes will be promulgated to further reduce criteria emissions from that this is a reasonable operating point to target for high new engines. Regulation for PM on a particle number basis BTE, but it should be understood that this is a more difficult has been introduced for vehicles and engines in Europe, and target than the old peak point target. At cruise, the engine California has studies under way on this subject. The EPA and must run at a load that is likely to be lower than the peak the Department of Transportation/National Highway Traffic efficiency operating load, and the engine speed may also be Safety Administration (DOT/NHTSA) announced proposed higher than the peak efficiency speed. The goal of 55 percent peak BTE has now been delayed from 2013 to 2018.3 This standards for fuel consumption and greenhouse gas (GHG) emissions for medium- and heavy-duty vehicles and engines stretch thermal efficiency goal of 55 percent in prototype on October 25, 2010 (EPA/NHTSA, 2010) and issued final engine systems would lead to a corresponding 10 percent standards on September 15, 2011 (EPA/NHTSA, 2011). gain in over-the-road fuel economy relative to the earlier 50 percent BTE goal at a corresponding condition representing 65 mph level road load cruise. The committee believes that DEPARTMENT OF ENERGY ENGINE PROGRAMS this will be a very difficult goal to achieve. DOE funding for FY 2007 to FY 2010 was provided for engine R&D in the following areas as shown in Table 1-2 Research and Development Programs (see Chapter 1 in this report): The DOE and the heavy-duty engine industry have been • Advanced Combustion Engine working in public-private partnerships to develop and dem- —Combustion and Emission Control (shared between onstrate advanced diesel engine technologies and concepts light- and heavy-truck engines) that improve engine thermal efficiency while meeting the —Heavy Truck Advanced Combustion Engine EPA’s 2010 emissions standards. The two technology goals —Waste Heat Recovery/Solid-State Energy Conversion established by the 21CTP for improving brake thermal effi- —Health Impacts ciency of heavy-duty engines are discussed in this section • Fuels Technology (DOE, 2011a). —Advanced Petroleum-Based Fuels–Heavy Trucks — Non-Petroleum-Based Fuels and Lubes–Heavy Programs and Projects Directed Toward Achieving 21CTP Trucks Goal 1 • Materials Technologies 21CTP Goal 1: Develop and demonstrate an emission —Propulsion Materials Technology–Heavy Trucks compliant engine for Class 7-8 highway trucks that —High Temperature Materials Laboratory achieves 50% brake thermal efficiency in an over-the- Progress in these areas since 2007 is discussed below road cruise condition, improving the engine fuel effi- in this chapter. ciency by about 20% (from approximately 42% thermal efficiency today) by 2015 (DOE, 2011a). Brake Thermal Efficiency Improvements The DOE’s targets for the improvement of engine brake The goal for 50 percent BTE discussed in the NRC Phase thermal efficiency have evolved over the years, sometimes in 1 report (NRC, 2008) was for the peak efficiency condition. ways that can be confusing, because different statements of a given goal can lead to varying interpretations. At the time of the 3 As noted in this chapter in the discussion on the 21CTP Goal 2, the NRC Phase 1 report published in 2008, the goals were set at 50 55 percent BTE goal in the 21CTP updated white paper, “Engines” (DOE, percent BTE in 2010 and 55 percent in 2013. These goals were 2011a) is for a prototype engine system in the laboratory by 2015. In the in terms of the peak efficiency demonstrated by an engine in a DOE Multi-Year Program Plan, the goal is for 2018 in a prototype engine test cell, where “peak efficiency” means the efficiency achieved (DOE, 2010d).

OCR for page 27
30 REVIEW OF THE 21ST CENTURY TRUCK PARTNERSHIP, SECOND REPORT TABLE 3-1 Accomplishments of High Efficiency Clean Combustion Projects Contract (Company, Project Leader, Number) Funding Dates Accomplishments Caterpillar, 4% BSFCa improvement below 750 kPa BMEP Chris Gehrke, DOE: $10,309,000 Start: August 2005 DE-FC26-05-NT42412 CAT: $10,309,000 Finish: July 2010 Cummins, DOE: $13,420,136 Start: October 2005 15 L engine: 10.2% improvement in brake thermal efficiency Donald Stanton, Cummins: $13,629,115 Finish: March 2010 (2010 in-cylinder NOx control) DE-FC26-05-NT42418 15 L engine: 16.4% improvement in brake thermal efficiency (2010 emissions with SCR NOx technology) 6.7 L engine: 14% improvement in fuel economy (Tier 2 Bin 8 emissions met without NOx aftertreatment) NOTE: Acronyms are defined in Appendix I. a Brake specific fuel consumption (BSFC) is a common and convenient measure of the thermal efficiency of an engine. It is the ratio of the mass of fuel consumed to the work produced by the engine; lower BSFC means higher thermal efficiency. It is different from efficiency in that it measures fuel consumption, whereas the efficiency is a dimensionless ratio that measures the portion of the fuel energy input that gets converted into work output. The two are related to one another through the energy content of the fuel. SOURCE: DOE (2010b) Annual Merit Review. FIGURE 3-1 High Efficiency Clean Combustion (HECC) engine efficiency improvements. SCR, selective catalytic reduction. SOURCE: Stanton (2010). 3-1.eps bitmap However, as noted above, the DOE revised the goal for 50 BTE by 10 percent compared to the 2006 product, accord- ing to the presentation to the committee.4 The essence of the percent BTE so that it is now for an over-the-road cruise condition. Programs and projects directed toward the devel- work was the development of clean combustion in the form opment of technology required to achieve Goal 1 include of low-temperature, highly premixed combustion combined High Efficiency Clean Combustion (HECC), Waste Heat with lifted flame diffusion controlled combustion. Using Recovery (WHR), the “NZ50” project at Detroit Diesel Cor- these technologies, 10 percent engine BTE improvement tar- poration (DDC), and others (DOE, 2011a). These programs gets have been achieved using no NOx aftertreatment. When and projects are reviewed in this section. Cost-effectiveness integrating HECC-developed technologies with SCR NOx was not part of these R&D projects, but cost-effectiveness aftertreatment system, further engine efficiency enhance- evaluations will be a required outcome of the SuperTruck ments were demonstrated. The results from the HECC proj- projects, as discussed in Chapter 8. ects are listed in Table 3-1 and shown in Figure 3-1. High Efficiency Clean Combustion 4 Donald Stanton, Cummins, Inc., “Cummins-Peterbilt Super Truck Program,” presentation to the 21CTP committee, September 9, 2010, A key objective of the HECC program has been to design Washington, D.C. and develop advanced engine architectures that improved

OCR for page 27
31 ENGINE SYSTEMS AND FUELS TABLE 3-2 Accomplishments of Waste Heat Recovery (WHR) Projects Contract Company, Project Leader, Number Funding Dates Accomplishments Caterpillar, DOE: $2,188,000 Start: October 2005 10% improvement in BTE was not achieved. Richard W. Kruiswyk, CAT: $2,188,000 Finish: June 2010 9% improvement target: 7 percent “virtual” demonstration. DE-FC26-05-NT42423 Demonstrated turbocompounding vs. Brayton cycle for bottoming. Demonstrated improvements in turbocharger compressor and turbine efficiencies. Cummins, DOE: $4,245,906 Start: June 2005 10% improvement in BTE (8% from WHR). Chris Nelson, Cummins: $4,488,836 Finish: March 2010 (Generation 1, No NOx AT, electric accessories) DE-FC26-05-NT42419 10% improvement in BTE (6% from WHR). (Generation 2, SCR NOx AT, no electric accessories) Both generations included Organic Rankine Cycle. NOTE: Acronyms are defined in Appendix I. SOURCE: DOE (2010b). by capturing and converting wasted heat energy to useful The historical thermal efficiency data shown in Figure work. A bottoming cycle or turbocompounding captures 3-1 indicate a drop in 2002, with only minor improvements heat from engine exhaust gas recirculation, charge air, and until 2010. This drop was caused by measures applied by exhaust streams. WHR systems were designed and developed engine manufacturers to meet requirements for lower NOx so that a bottoming device could be coupled to the engine emissions (NRC, 2010, Figure 4-2). With NOx requirements either mechanically or electrically through a high-speed now stabilized, engine manufacturers will be able to refocus generator. The results from these projects are listed in Table efforts on thermal efficiency improvements. 3-2. The Cummins WHR system is shown in Figure 3-2 (Nelson, 2010). Waste Heat Recovery The highest-quality source of heat for WHR comes from the EGR stream, as illustrated in Figure 3-2. As the effective- The objective of the WHR program is to improve engine ness of SCR is further improved, the use of EGR is likely to BTE by 10 percent (i.e., from 42 percent to 46 percent BTE) FIGURE 3-2 Cummins Waste Heat Recovery (WHR) system, second-generation architecture. Acronyms are defined in Appendix I. SOURCE: Nelson (2010). 3-2.eps bitmap

OCR for page 27
32 REVIEW OF THE 21ST CENTURY TRUCK PARTNERSHIP, SECOND REPORT TABLE 3-3 Accomplishments of Other Engine Projects Funded in Part by the Department of Energy Contract Funding Dates Accomplishments DDC/Daimler NZ50, DOE: $5,000,000 Start: February 2007 Goal: 10% improvement in BTE. Kevin Sisken and DDC: $5,000,000 Finish: 2010 Results: Combustion, 4% (2% more expected); controls, 3%; Houshan Zhang, turbocharger, 1%. DE-FC05-00-OR22805 Navistar––Low DOE: $4,021,234 Start: October 2005 Goal: 5% BSFC at 2010 emissions, no AT Temperature Combustion Navistar: $5,153,881 Finish: May 2010 Fuel economy improved 4% to 5.5% (with PCCI, VVA, and combustion Demonstration for High feedback). Efficiency, Load range for LTC extended to 16.5 bar BMEP William de Ojeda, DE-FC26-05-NT42413 General Motors, DOE: $5,000,000 Start: 2005 Achieved 5% to 8% lower BSFC with internal EGR and VVA. Kenneth Patton, GM: $5,000,000 Finish: 3rd Quarter, 2009 Ford Motor Company, DOE: $1,500,000 Start: October 2007 Goal: Demonstrate a turbocharger with 3% to 5% fuel economy Harold Sun, Ford: $1,500,000 Finish: June 2010 improvement at Tier II Bin 5 emissions. DE-FC26-07-NT43280 2010 DEER presentation (Sun et al., 2010): Not obvious if the goals were met. NOTE: Acronyms are defined in Appendix I. SOURCE: DOE (2010b). and develop multifuel vehicles and drivelines. The FY 2010 decline, which would reduce the potential benefit of WHR. accomplishments were as follows (DOE, 2009): If only the lower-quality heat sources (post-aftertreatment exhaust gas, charge air, and coolant) were available to • A turbocompound engine showed 5 percent lower fuel be captured, the efficiency of the WHR system would be consumption. Computational fluid dynamics (CFD) expected to decrease. Therefore, the trade-off between the modeling shows that a high-performance piston can use of higher-efficiency SCR systems with the decrease in improve BTE by 1 percent. effectiveness of the WHR system will need to be balanced. • A parallel Rankine cycle WHR system can improve BTE by approximately 7 percent at B507 and 8.5 per- Other Projects cent at C100.8 • Analysis of mechanical, electrical, and electrome- Detroit Diesel/Daimler, Navistar, General Motors, and chanical transmission alternatives to connect the turbo- Ford Motor Company also had projects summarized in compound power turbine to the crankshaft showed the Table 3-3. mechanical transmission best for fuel consumption. Volvo had a project that started in October 2007 and • Hybridization simulation showed 2 percent to 8 per- finished in September 2009. It was funded at $9 million, cent fuel consumption reduction in European applica- with the DOE contributing $3 million and Volvo $6 million (subtopic 6B of DOE-FOA-00002395). The results showing tions and zero percent to 2.2 percent in typical U.S. applications. lower brake specific fuel consumption (BSFC) by 3 percent • A biofuel B209 endurance truck test was initiated were presented at the DOE 2009 Merit Review. It appears (DOE, 2009). that this project is also reported as the Bilateral Program being conducted by Volvo Powertrain North America and Volvo AB of Sweden.6 It is jointly funded by the DOE and The nine diesel engine programs and projects reviewed above are examples of DOE public-private partnerships. the Swedish Energy Agency. The objectives are to reduce As indicated previously, several programs exceeded their CO2 by 10 percent while meeting 2010 EPA criteria emis- goals of 5 percent or 10 percent improvement in BTE. Not sions, develop an engine platform capable of biodiesel fuel, all programs met their goals, but some programs sorted out technologies and identified them for further development. 5 Funding Opportunity Announcement (DOE, 2010b) available at http:// 7 www1.eere.energy.gov/vehiclesandfuels/pdfs/de-foa-0000239.pdf . B50, a point on the EPA supplemental engine test (SET), 50 percent 6 E-mail, Rich Bechtold to committee member, David Merrion, November load, mid-speed. 8 C100, a point on the EPA SET, 100 percent load, high speed. 18, 2010, report II.A.20 “Very High Fuel Economy, Heavy-Duty, Narrow- 9 B20, 20 percent biofuel mixed with diesel fuel. Speed Truck Engine utilizing Biofuels and Hybrid Vehicle Technologies.”

OCR for page 27
33 ENGINE SYSTEMS AND FUELS get of 50 percent peak BTE. However, the DOE target of 50 The demonstrations of BTE improvements were accom- percent peak BTE was not met by the original goal of 2010. plished mainly at peak BTE operating conditions, with 42 percent as the baseline. As discussed in the NRC Phase 1 Finding 3-1a. The DOE has shifted the original target of report (NRC, 2008), the BTE goal should be demonstrated 50 percent peak BTE by 2010 to a new target of 50 percent at a more representative road load cruise condition, which BTE at an operating point representative of vehicle load is now incorporated in 21CTP Goal 1. The Cummins dem- during highway cruise operation. This makes the efficiency onstrations, such as those shown in Figure 3-1, were at a target more difficult to meet and may require complex and highway cruise condition. expensive technology that extends beyond the technologies The current SuperTruck projects call for the contractors demonstrated on engines to date. These technologies will not to demonstrate the 50 percent BTE target at cruise load necessarily be production-feasible or cost-effective. on engines installed in vehicles by the end of 2014. If the contractors are able to meet the target, this would enable the 21CTP Goal 1 to be met by 2015. It should be noted that the Programs and Projects Directed Toward Achieving 21CTP SuperTruck projects include efforts to reduce the load that Goal 2 the vehicle places on the engine as well as to improve the 21CTP Goal 2: Research and develop technologies which efficiency of the engine. By lowering the load on the engine, achieve a stretch thermal efficiency goal of 55% in pro- the SuperTruck projects will actually make reaching the 50 totype engine systems in the laboratory by 2015 (DOE, percent efficiency goal at cruise conditions more difficult 2011a). (see Chapter 8 for more detail). There is some risk that the engine thermal efficiency goal will not be met, or that meet- In the public-private DOE partnerships discussed, indus- ing the goal will require complex and expensive technology try participants have provided technology roadmaps of their that would be difficult to implement in production and which strategies for achieving brake thermal efficiencies of 50 may not be cost-effective. and ultimately 55 percent. Improving the efficiency of the Finding 3-1. The committee reviewed nine diesel engine in-cylinder conversion of fuel energy into shaft work is an important component of each participant’s roadmap. To do programs that were funded at a total of more than $100 mil- this, all of the participants project incorporating new modes lion by the DOE and industry and that included the HECC of combustion into their engine operation. Figure 3-3 is an program, the WHR program, and others. Some programs met example of the integration of new combustion technologies, or exceeded their goals, for example achieving a 10.2 percent like HECC and low-temperature combustion (LTC), that will improvement in BTE versus a 10 percent goal, whereas oth- be needed to achieve the efficiency targets of the program ers did not quite meet the goals of 5 percent or 10 percent (NRC, 2008). improvement in BTE. By combining HECC and WHR, each Gaining the requisite fundamental understanding of the demonstrating greater than 10 percent improvement in BTE, phenomena governing advanced combustion modes, such together with other technologies, it should be possible to as those shown in Figure 3-3 (early pre-mixed charge com- improve BTE by 20 percent to achieve the original DOE tar- pression ignition [PCCI, LTC] and lifted flame diffusion FIGURE 3-3 Schematic representation of the evolution of combustion processes to be used at different engine loads and speeds. Acronyms 3-3.eps are defined in Appendix I. SOURCE: Gurpreet Singh, DOE, “Overview of the DOE Advanced Combustion Engine R&D Subprogram,” presentation to the committee, November 15, 2010, Washington, bitmap D.C.

OCR for page 27
34 REVIEW OF THE 21ST CENTURY TRUCK PARTNERSHIP, SECOND REPORT controlled combustion), is the focus of the DOE combustion National Laboratory [ANL], Lawrence Livermore National activities within the national laboratories, industry, and aca- L aboratory [LLNL], Los Alamos National Laboratory demia. These advanced modes of combustion are achieved [LANL], Oak Ridge National Laboratory [ORNL], Sandia through synergistic interactions between the auto-ignition National Laboratory [SNL], and the National Renewable and reaction kinetics of the fuel, the thermodynamic states Energy Laboratory [NREL]). The energy companies joined within the cylinder—the pressure, and distributions of tem- the AEC MOU in late 2006 and brought a research focus perature, fuel, oxygen, nitrogen, and the recirculated exhaust involving fuel effects on advanced combustion strategies. gases—and the rate of the mixing within the cylinder. The The MOU was recently unanimously renewed by the partners mixing processes are manipulated through fuel injection through 2013. characteristics and in-cylinder fluid mechanics, which in As part of the 21 CTP Phase 2 review process, a list of turn are influenced by the shape of the combustion chamber nine DOE-funded projects focused on advanced combustion and subject to manipulation through the intake and exhaust that were directly attributed to the 21CTP was supplied by processes, which can be controlled by engine valve actuation. the DOE to the committee. These projects are listed in Table To maintain robust combustion throughout the engine operat- 3-4 and were budgeted in FY 2010 for $5.66 million. ing range with multimode combustion requires the dynamic There is interaction and leverage between these projects manipulation of a wide range of engine control variables. and other DOE-supported combustion projects, but these The goals of the DOE laboratory and university research projects were specifically designated by the DOE as being programs are to develop the fundamental understanding under the 21CTP umbrella, so the discussion below is limited and tools necessary to facilitate such a high level of engine to these projects. combustion control. Researchers participating within each of the nine projects This fundamental research is conducted under the have developed collaborative teams consisting of industry Advanced Engine Combustion Memorandum of Understand- and academic partners. Academic participants are required ing (AEC MOU) between industry and national laboratories to establish a 20 percent cost share. Everyone participates that was initiated in 2003. The partners involved in the AEC in two group research meetings per year and in an annual MOU include 10 engine producers (Caterpillar, Cummins, merit review as part of the DOE’s Energy Efficiency and Detroit Diesel, Navistar/International, John Deere, Mack/ Renewable Energy (EERE) program. Project directions and Volvo, General Electric, General Motors, Ford, and Chrys- continuation are based on the scores received in the merit ler), 5 energy companies (Chevron, ConocoPhillips, Shell, review. The presentations given at the merit review are avail- ExxonMobil, and BP), and 6 national laboratories (Argonne able to the public (DOE, 2010b). TABLE 3-4 Major 21CTP-Related Projects Addressing Advanced Combustion Fundamentals DOE Funding: DOE Funding: Title Organization FY 2009 Budget FY 2010 Budget KIVA 4 Development (advanced computer program) LANL $290,000 $290,000 Computationally Efficient Modeling of High-Efficiency Clean LLNL $1.0 million $1.0 million Combustion Chemical Kinetic Research on HCCI and Diesel Fuels LLNL $400,000 $400,000 Stretch Efficiency for Combustion Engines: Exploiting New ORNL $250,000 $250,000 Combustion Regimes HCCI and Stratified-Charge Compression Ignition Engine Combustion SNL $750,000 $750,000 Research Heavy-Duty Low-Temperature and Diesel Combustion Modeling SNL $580,000 with $660,000 with $115,000 subcontract $115,000 subcontract to UW-Madison to UW-Madison Combustion Modeling Large Eddy Simulation Applied to LTC/Diesel/ SNL $450,000 $450,000 Hydrogen Engine Combustion Research Low-Temperature Diesel Combustion Cross-Cut Research SNL $570,000 $660,000 Optimization of Advanced Diesel Engine Combustion Strategies University of $360,000 $1.2 million Wisconsin–Madison NOTE: Acronyms are defined in Appendix I. SOURCE: DOE (2010b). Available at http://www1.eere.energy.gov/vehiclesandfuels/resources/proceedings/2010_merit_review.html.

OCR for page 27
35 ENGINE SYSTEMS AND FUELS The focus of the research projects listed in Table 3-4 is the engine-out emissions that have been achieved. Highlights of development of a greater fundamental understanding of the two of these research projects are summarized here. processes that need to be sensed, and controlled, for the inte - gration of advanced, high-efficiency clean combustion pro- • Gasoline HCCI: HCCI—or, more generally speaking, cesses, into the engine operating map. The work includes the low-temperature combustion strategies—applied in the continued development of the advanced computer program laboratory environment, using conventional gasoline, KIVA, which is the framework that researchers use for model have achieved light-load operation down to engine development, and the development of higher-resolution tur- idle conditions and loads as high as 16 bar brake mean bulence models for better spray and fluid-mixing simulation. effective pressure (limited by the laboratory engine Comprehensive kinetic routines for diesel-like, gasoline-like, head design) offering the possibility of an engine oper- and representative biofuels are an important aspect of the ating with LTC over a large portion of the engine map. research. These routines identify the critical chemical kinetic Peak indicated efficiencies in a light-truck-size engine pathways that must be included in the simulation for accurate of 48 percent were achieved with NOx levels less than results, which in turn allows for the development of reduced the 2010 standard, near-zero soot levels, and controlled kinetic schemes that are critical for computational efficiency. heat release to provide low noise and preclude engine Reduced kinetic schemes are only one aspect of developing knock (Ra et al., 2010). computationally efficient simulations. Research is being • Dual-Fuel LTC: Recent research in heavy-duty engines supported that addresses computationally efficient methods with dual-fueled (gasoline- and diesel-fueled) HCCI/ of solving thermodynamic, fluid mechanic, and chemical LTC approaches are indicating potential for 50+ per- kinetic coupled systems. cent brake thermal efficiencies, controlled heat release An integral part of this fundamental research consists of rates, and 2010 emissions levels. Dual-fuel operation the detailed experimental measurements that identify the has been achieved from 4 to 17 bar BMEP in a heavy- important phenomena occurring within the reacting systems, duty laboratory engine, while achieving NOx levels which aids in the model development and serves as a basis for below the 2010 standard and near-zero soot levels. The the comparison of model predictions. Spatially and tempo- start of combustion timing is controlled by the diesel rally resolved data are being obtained with advanced optical fuel injection, and the heat release rate is controlled by the gasoline fraction.10,11 This work has recently been diagnostics techniques. Such measurements have elucidated the effects of in-cylinder temperature and mixture stratifica- extended, with encouraging results to bio-based fuels tion on LTC processes, differences in particulate formation and single fuels with the addition of a cetane improver processes for varying combustion regimes, and details of (Splitter et al., 2010). the fuel distribution and wall interactions associated with pulsed injection, an important component of controlling LTC T he improved fundamental understanding has also processes. Finally, work is being supported that endeavors advanced computational tools for engine design. Most engine to combine all of the advanced understanding and perform designers are increasingly and aggressively using computa- optimization studies and to push the efficiency boundaries by tional tools developed through support by DOE’s Vehicle pursuing advanced combustion concepts to reach the stretch Technologies Program for experimental research and engine efficiency goals. CFD development efforts. The growing use of computational The fundamental combustion and emissions research to tools for engine design is exemplified by Cummins intro- date under the AEC MOU has led to significant advances in duction of the ISB 6.7-liter (L) light-truck (Class 2b) diesel the understanding of various strategies for achieving LTC. in 2007. This diesel engine was computationally designed Critical aspects of how HCCI and diesel LTC progress, with much reduced testing to confirm performance. The how their heat release rate and combustion phasing can be design process led to reduced design time and a more robust controlled, the sources of hydrocarbon (HC) and carbon design with reduced fuel consumption while meeting 2010 monoxide (CO) emissions when the LTC approaches are emissions standards (for trucks over 8,500 lb using chas- pushed to limits of operation, and fuel effects on LTC are sis dynamometer certification). The future introduction of being unraveled. more robust computational design tools able to simulate the Higher efficiencies in heavy-duty truck engines have also full range of engine combustion approaches (conventional been shown in the laboratory. Implementation of diesel LTC mixing-controlled diesel combustion premixed and stratified approaches has begun in heavy-duty diesels for a portion of flame propagation, the LTC bulk ignition and combustion the fuel burned during moderate- to light-load parts of the engine operating range, providing significant engine-out 10 Gurpreet Singh, DOE, “Overview of the DOE Advanced Combustion emissions reduction. In general, higher injection pressure, Engine R&D Subprogram,” presentation to the committee, November 15, multipulse injection, and EGR use have allowed a greater 2010, Washington, D.C. fraction of the reactive mixtures during diesel combustion to 11 Kevin Stork, DOE, “DOE Fuel and Lubricant Technologies R&D,” be pushed toward LTC conditions, contributing to the lower presentation to the committee, November 15, 2010, Washington, D.C.

OCR for page 27
36 REVIEW OF THE 21ST CENTURY TRUCK PARTNERSHIP, SECOND REPORT 2011a).12 This efficiency gain would be equivalent processes) has very strong potential to lead to even faster to an additional 10 percent gain in over-the-road fuel evolution and improvement of cost-effective engines. economy when prototype concepts are fully developed Finding 3-2. The DOE-funded research in advanced engine for the market. combustion at the national laboratories, in industry, and at The SuperTruck engine programs are discussed in this sec- universities is well managed and addresses important aspects tion; the vehicle programs are discussed in Chapter 8.13,14,15 for achieving an integration of advanced combustion pro- cesses that should be important enablers for achieving the • Daimler Trucks/Detroit Diesel: Technologies listed in 55 percent BTE goal as well as providing ongoing improve- the September 9, 2010, presentation to the committee ments. There also appears to be good interaction between the are as follows researchers performing the work and the industry stakehold- —Advanced fuel injection, ers. Efforts to achieve 55 percent BTE are going to require —Optimized combustion, complex and expensive technologies. It will be some time —Air/EGR refinement, before it becomes clear whether there is a production-feasible —Friction reduction, and cost-effective way to achieve the 55 percent BTE target. —Accessories, The committee believes that this target carries considerable —More efficient operating point, risk, even at the test cell demonstration stage. —Waste heat recovery, Recommendation 3-1. The 21CTP fundamental research —Next generation controller, —Higher engine out NOx, program should continue to provide important enablers for —Engine downsizing, the 55 percent BTE goal, and the DOE should continue to —Optimized aftertreatment. look for leverage opportunities with other government- and • Cummins: Technologies listed in Cummins’s Septem- industry-funded projects. ber 9, 2010, presentation to the committee, the Cum- mins’s presentation to the DOE DEER Conference Future Engine R&D in the SuperTruck Program September 29, 2010, and the company’s presentation during the committee’s site visit to the Cummins on The DOE, in 2010, announced three SuperTruck project November 8, 2010 (see Appendix B) are as follows: awards to demonstrate engine and truck efficiency enhance- —Fuel system, ments for Class 8 vehicles in real-world conditions (see —Advanced LTC, Chapter 8). The aim of these developments is to foster —Controls: electronic, quicker introduction of new technologies into the market- —Electrically driven components, place, thereby achieving energy savings later in this decade. —Waste heat recovery: EGR, charge air, exhaust heat, The DOE made the decision to carry out future engine mechanical coupling, R&D under the SuperTruck program, but it retained Goals —Aftertreatment, 1 and 2 discussed above. Key engine technology demon- —Turbo technology, strations under the 5-year SuperTruck program include the —EGR loop, following: —Variable valve actuation (VVA), — Base engine: peak cylinder pressure, friction, • Engine Goal 1: Develop and demonstrate a 2010 emis- parasitic. sions compliant engine system for Class 8 trucks that • Navistar: Technologies listed in Navistar’s September achieves 50 percent BTE at an over-the-road cruise 9, 2010, presentation to the committee and its presenta- condition by improving engine efficiency 20 percent tion during the committee’s site visit to the Navistar, from 42 percent BTE today, by 2015 (DOE, 2011a). This improvement in engine BTE will provide at least 20 percentage points of the 50 percent improvement in vehicle freight efficiency (ton-miles per gallon) 12 The DOE uses the term “stretch” for goals that cannot be achieved by (equivalent to 33 percent improvement in fuel con- incremental or small improvements and are thus very difficult to achieve, sumption [gallons per 1,000-ton-miles]), which is the which seems appropriate for federal programs. The committee supports overall goal of the SuperTruck program. the use of this terminology because this thermal efficiency goal will be • Engine Goal 2: Research and develop technology path- difficult to achieve. 13 Derek Rotz, Daimler, “Daimler’s SuperTruck Program,” presentation ways using modeling and analysis to achieve a stretch to the committee, September 9, 2010, Washington, D.C. goal of 55 percent BTE in a 2010 emissions compli- 14 Donald Stanton, Cummins, “Cummins-Peterbilt SuperTruck Program,” ant engine system in the laboratory, by 2015 (DOE, presentation to the committee, September 9, 2010, Washington, D.C. 15 Anthony Cook, Navistar, “Navistar’s Super Truck Program,” presenta - tion to the committee, September 9, 2010, Washington, D.C.

OCR for page 27
37 ENGINE SYSTEMS AND FUELS Finding 3-3. Future engine R&D for Goal 1, develop and Inc., Truck Development and Technology Center on January 13, 2011, are as follows: demonstrate 50 percent BTE at over-the-road cruise condi- —Combustion efficiency improvement: tions by 2015, and for Goal 2, research and develop technol- Injection pressure, nozzle, bowl optimization, com- ogy pathways to achieve a stretch goal of 55 percent BTE in bustion feedback control, cylinder head and port; a 2010 emissions-compliant engine system in the laboratory —Air system enhancements: by 2015, will be carried out under the SuperTruck program. Turbocharger efficiency, hybrid EGR system; The engine programs outlined by the three SuperTruck —WHR (turbocompounding and Rankine): project teams appear to be comprehensive and are expected Rankine cycle—Common cycle used to gener- to achieve the 50 percent BTE goal, although there is risk in ate electricity, fluid development for typical truck being able to achieve the goal at a cruise condition with the engine heat range; significantly reduced power demand level of the SuperTruck. Turbocompounding—Dual turbines, visco-mechan- Developing engine technology pathways to achieve the ical drive to the crankshaft, microturbine; stretch goal of 55 percent BTE in an engine in a laboratory by —Aftertreatment: 2015 is considered very high risk, but might be achievable. Minimize regeneration, opportunistic regeneration, Recommendation 3-2. The DOE should ensure that the PM-NOx balance; —Friction reduction/insulation: engine R&D for the goal of 50 percent BTE at over-the-road Low friction, weight reduction, electrification of cruise conditions and the stretch goal of 55 percent BTE in engine accessories, drive mechanism improvements, an engine in a laboratory that will now be carried out under heat rejection reduction, insulated exhaust ports and the SuperTruck program receive the appropriate share of the manifolds; SuperTruck funding and benefit extensively from the DOE- —VVA: funded research programs in advanced engine combustion. Effective compression ratio control, cylinder deacti- vation; ENGINE PROGRAMS OF THE ENVIRONMENTAL —Dual fuel (gasoline and diesel). PROTECTION AGENCY The SuperTruck engine programs are a continuation of the The EPA is developing several candidate types of engines previously discussed DOE diesel engine programs and have specifically for application to its series hydraulic hybrid truck programs.16 Although the DOE is not funding the EPA, the the same goals as those previously discussed. It is unlikely that other heavy-duty diesel engine programs will be funded EPA’s work fits under the 21CTP. The engines that are under by the DOE. (Also see the Findings and Recommendations development by the EPA are (1) optimized alcohol engines in Chapter 8 regarding the SuperTruck projects.) and (2) homogeneous-charge compression ignition engines. In the 21CTP projects to date, as described earlier in this The BTE values of these engines are approaching the 42 chapter, 50 percent BTE has not been demonstrated in an percent BTE of current diesel engines, as shown in Table 3-5. engine in a vehicle. Significant advancements have been made for individual technologies, which, if combined in an High-Efficiency Alcohol-Fuel Engines engine, are expected to provide the key elements required to improve BTE by 20 percent to achieve the 50 percent BTE The EPA has been developing optimized alcohol-fueled goal. The requirement to demonstrate 50 percent BTE at engines for the high-octane E85 fuels that can potentially an over-the-road cruise condition poses an additional task, provide a cost-effective engine technology suitable for both because the best point for BTE is typically at a higher load. conventional and hybrid vehicles for the medium-duty fleet Adding to this task will be the significantly reduced power truck market. The high-octane number of alcohol, together demand at the over-the-road cruise condition resulting from with its latent heat of vaporization, enable the use of high the SuperTruck vehicle improvements. compression ratios and boosted applications. Alcohol’s high The SuperTruck project teams revealed few, if any, plans laminar flame speed relative to gasoline permits greater concerning the research and development of technology path- charge dilution with EGR, reducing the need for throttling ways to achieve a stretch goal of 55 percent BTE. Moving at light to moderate loads while still allowing stoichiomet- toward this goal is expected to build on the future achievement ric operation that facilitates the use of a three-way catalyst of the 50 percent BTE goal and to rely heavily on the DOE- (Brusstar and Gray, 2007). The EPA has achieved current funded research programs in advanced engine combustion dis- diesel levels of BTE with E85 fuel using conventional three- cussed in the previous section. Without having specific plans way catalysts to meet the 2010 emissions standards. to review for this goal, the committee considers the 55 percent BTE very high risk, although it might be achievable. 16 John Kargul, EPA, “Clean Automotive Technology, Cost Effective Solutions for a Petroleum and Carbon Constrained World,” presentation to committee subgroup, October 26, 2010, Ann Arbor, Michigan.

OCR for page 27
48 REVIEW OF THE 21ST CENTURY TRUCK PARTNERSHIP, SECOND REPORT facilitating at least 5 percent replacement of petroleum efficiency and very low emissions, and facilitating at fuels. least 5 percent replacement of petroleum fuels.” • By 2010, identify and exploit fuel properties that Status: This DOE goal was discussed in detail in the could increase efficiency and reduce overall tailpipe NRC Phase 1 report (NRC, 2008). For this present emissions through (1) lower engine-out emissions, review, the DOE reported that it contributed to an including new low-temperature combustion regimes, improved biodiesel ASTM specification, resolving and (2) enhancement of aftertreatment performance s hortcomings of the ASTM D6751 specification for 2010 emissions regulations. i ssued in 2002. The DOE also reported on stud- • By 2013, identify non-petroleum fuel formulations ies under way to determine the factors (including (i.e., renewables, synthetics, hydrogen-carriers) for radiative heat transfer, reaction rates, and combustion advanced engines and new combustion regimes for the t emperatures) that result in increased NO x e mis - post-2010 time frame that enable further fuel economy sions when fueling with biodiesel. A set of common benefits and petroleum displacements while lowering research fuels were developed, analyzed, and distrib - emissions levels to near zero, thus adding incentives uted for understanding low-temperature combustion for using non-petroleum fuels. ( the FACE project), although a low-temperature combustion engine for testing these fuels had not A draft white paper presented to the committee on been identified. The NRC Phase 1 report did not November 15-16, 2010, provided the following new list of contain plans for achieving the goal of replacing 5 21CTP fuels and lubricants goals (DOE, 2010a). The new percent of petroleum fuel with nonpetroleum fuels Goal 3 repeats the earlier Goal 1, and the new Goal 4 repeats by 2010. The DOE subsequently reported that zero the earlier Goal 3. The status of each goal is provided in the percent reduction in petroleum consumption for the comments following each goal. Little or no progress has been total heavy-duty truck fleet was achieved in 2010, but forecasted a 5 percent reduction in 2015.35 made on these goals because DOE funding reductions in fuels and lubricants technologies have resulted in no funding • New 21CTP fuels and lubricants Goal 4: “By 2013, for heavy-duty fuels and lubricants R&D. identify non-petroleum fuel formulations (e.g., renew- ables, synthetics, hydrogen-carriers) for advanced • New 21CTP fuels and lubricants Goal 1: “Establish engines and new combustion regimes for the post-2010 the influence of fuel and lubricant sulfur on emission- time frame that enable further fuel economy benefits control technologies.” and petroleum displacements while lowering emis- Status: The 21CTP engine white paper dated August sions levels to near-zero, thus adding incentive for 30, 2010, states: “The sulfur and ash content of lubri- using non-petroleum fuels.” cants are sufficiently high to be factors in degradation Status: The NRC Phase 1 report (2008) stated that this of performance of NOx adsorber catalysts and to influ- goal “was intended to emphasize the development of ence the cleaning intervals and regeneration phenom- non-petroleum fuel formulations beyond biodiesel,” ena in DFPs, for example.” No progress was reported previously addressed by Goal 1. Similar to Finding to the committee for this goal. 3-15 in the NRC Phase 1 report, the DOE provided • New 21CTP fuels and lubricants Goal 2: “Identify little insight into the scope and magnitude of the and exploit fuel properties that reduce overall tailpipe effort to address this goal. The Phase 1 report stated, emissions through lower engine-out emissions, includ- “It appears unlikely that the fundamental mechanisms ing new low-temperature combustion regimes and that control the formation of HC, NOx, and particulate enhancement of aftertreatment performance.” emissions in a diesel engine can be dramatically altered Status: The 21CTP engine white paper dated August with a change in fuel formulation to the extent that the 30, 2010, states: “The understanding of fuel property emissions could approach zero.” effects on emissions is highly empirical. Similarly, understanding the relation between fuel properties and Another draft 21CTP engine white paper dated February low-temperature combustion modes is far from well- 25, 2011 (DOE, 2011a) states the goal for fuels as follows: understood.” The DOE reported that high-volatility diesel (HVD) fuel increased efficiency and lowered • “Through experiments and models with FACE fuels emissions for PCCI operation according to optical and other projects, determine the most essential fuel engine studies, which showed that liquid fuel films on properties, including renewables, needed to achieve 55 the piston are avoided. percent engine brake efficiency, by 2014.” • New 21CTP fuels and lubricants Goal 3: “By 2010, identify and validate fuel formulations optimized for 35 Kevin Stork, DOE, “Fuel & Lubricant Technologies R&D Overview use in advanced combustion engines exhibiting high for NAS Review of 21CTP,” presentation to the committee, November 15, 2010, Washington, D.C.

OCR for page 27
49 ENGINE SYSTEMS AND FUELS aftertreatment systems. Also, highly effective aftertreatment Status: Plans for achieving this goal were not reviewed systems can facilitate different engine calibrations for bet- with the committee. As noted in an earlier section, ter efficiency, which would otherwise have been precluded significant progress in low-temperature combustion because of emission constraints. Aftertreatment research and has been realized through the use of gasoline or dual development must be done with an eye toward the likely gasoline and diesel fuels. The DOE should recognize progress in combustion system development. this progress in defining this goal and developing spe- In addition, aftertreatment systems are the subject of cific plans for achieving the goal. extensive research within the technical community. Con- Finding 3-9. The DOE established three different sets sequently it is critical for the 21CTP be aware of the broad scope of activities taking place outside of its program and of goals for the fuels program from 2008 to 2011, which to make sure that the research activities within its purview made an assessment of progress against the goals difficult. address fundamental concerns and are not already being done In total, little progress has been made toward the achieve- as part of the research and development efforts of the other ment of these DOE goals, which were not specified goals agencies or industry. of the 21CTP. To this end, the research structure of the 21CTP aftertreat- Recommendation 3-6. The DOE fuel goals should be ment program is well organized. The research programs are built around teams with participation from national labora- re-evaluated in line with the FY 2012 budget and the recom- tories, universities, and relevant stakeholder industries. This mendations of this report. Specific plans for achieving these is directly stated in the goals of their aftertreatment program. goals should be established. The research focuses on developing new technologies and on gaining an enhanced fundamental understanding of catalysis AFTERTREATMENT SYSTEMS and governing phenomena limiting the effectiveness of cur- rent approaches. Success in these programs could lead to Introduction combining multiple aftertreatment approaches into a single unit, developing catalysts with higher resistance to poison- Considerable effort and research funding have been ing, and implementation of retrofit systems. focused on improving aftertreatment systems as part of the The 21CTP aftertreatment research has already helped 21CTP. This effort is complementary to the development manufacturers meet the EPA 2007 and 2010 new-engine of combustion processes that would minimize or preclude emissions standards. The system architecture generally the in-cylinder formation of criteria pollutants. It is most being applied to meet U.S. EPA 2010 emissions is shown appropriate to think of the combustion processes within the in Figure 3-4. The attainment of these emission standards cylinder and the aftertreatment devices within the exhaust is providing substantial health and environmental benefits as an interconnected system. Minimal emissions leaving by reducing ground-level ozone and fine particulates (mass the combustion chamber result in reduced demands on the as well as number), in addition to regional haze. Thus, con- aftertreatment system, allowing for simpler, less expensive FIGURE 3-4 Emission control system architecture generally being applied to meet 2010 new engine emissions standards of the Environ - 3-4.eps mental Protection Agency. Acronyms are defined in Appendix I. SOURCE: DOE (2011a). bitmap

OCR for page 27
50 REVIEW OF THE 21ST CENTURY TRUCK PARTNERSHIP, SECOND REPORT Goals tinued research into improved aftertreatment is extremely important. The 21CTP responded to the recommendations of the Diesel particulate filters have reduced diesel particulate NRC Phase 1 review with a critical evaluation of the role of matter by approximately 90 percent. Particulate matter aftertreatment in meeting its overall program goals and has emitted from modern diesel engines is typically in the size written a white paper specifying the role of aftertreatment range of 10 to 250 nanometers (µm). There are concerns that within its program (DOE, 2011a). Formally the 21CTP has current regulatory limits for particulate matter from engines, identified six goals specifically related to aftertreatment tech- which are in terms of emitted mass, are not a proper measure nologies. These goals are as follows with comments from the of the health hazard. One particle of 10 micrometers (µm) committee on the work supporting these goals. diameter has approximately the same mass as 1 million par- ticles of 100 nm diameter. There is evidence that particles • 21CTP Goal 1 related to aftertreatment technologies: smaller than 100 nm can pass through cell membranes and “Improve performance and durability of NOx control migrate into other organs. Research into the potential health technology through improved combustion and after- impacts of very small particles is currently being sponsored treatment processes, sulfur management, reductant by the Health Effects Institute (HEI). Proposals for new strategies, and improved materials.”36 regulations exist in some countries, with suggestions to limit Comment: This goal would appear to be met by further the particle surface area or the particle number. Although reduction of sulfur in the diesel fuel, and developments particulate number regulations are not in effect in the United of SCR catalysts, lean NOx traps, DEF reductants, low States, they are being considered. Vehicles equipped with temperature combustion, and iron and copper zeolite particulate filters should have no difficulty meeting newly materials. proposed particle number regulations. However, as new • 21CTP Goal 2 related to aftertreatment technologies: combustion technologies, such as LTC and high injection “Develop and apply advanced fuel injection, engine pressure, lifted flame, mixing controlled combustion, are c ontrol strategies, new combustion regimes, air- integrating into the engine map, it may be possible to meet handling, and aftertreatment for emissions reduction, the particulate mass regulation without a filter. Under such with modeling, simulation and controls integrated in situations it will be important to understand the characteris- the approach.” tics of the particulate number being emitted from these future Comment: This goal would appear to be met through combustion systems. Technologies to address this issue will the various CRADAs and research projects discussed be needed in the future. in this chapter. • 21CTP Goal 3 related to aftertreatment technologies: Response to Recommendations from NRC Phase 1 Review “Develop and implement cost effective retrofit emis- sion control technologies.” Prior to 2007, the aftertreatment goals of the 21CTP were Comment: OEM systems for PM control and NOx focused on (1) meeting the 2007 heavy-duty engine emission control have been supported, and these have made their standards and (2) eliminating the need for aftertreatment. In way into retrofit (aftermarket) systems, but no direct its Phase 1 review of the 21CTP (NRC, 2008), the commit- support of retrofit systems or programs are evident. tee found that no specific goals had been outlined for 21CTP • 21CTP Goal 4 related to aftertreatment technologies: diesel engine aftertreatment systems, but some goals had “Determine the best configuration and controls for NOx been set for eliminating aftertreatment. The committee found and particulate matter (PM) reduction through engine/ that the goal of eliminating aftertreatment did not appear to aftertreatment integration.” be achievable in the foreseeable future. The committee also found that the Crosscut Lean Exhaust Emissions Reduction Simulations (CLEERS), Diesel Crosscut Team (DCT), and CRADAs had contributed to many successful projects and 36 Fundamental work is being done to improve the reduction efficiency programs. The NRC Phase 1 review recommended that spe- (performance) of NOx aftertreament systems, with particular emphasis on cific goals should be set for aftertreatment systems (improved high mileage (durability) where compliance with applicable standards is required. The higher the efficiency of the aftertreatment system the larger efficiency, lower fuel consumption, lower cost of substrates, the cylinder-out NOx can be. The efficiency of the NOx aftertreatment system lower-cost catalyst, etc.) and that the 21CTP should con- ends up constraining the allowable NOx leaving the cylinder. Constraining tinue with the CLEERS, DCT, and CRADA activities for the cylinder-out NOx constrains what one can do to improve the efficiency aftertreatment systems. The 21CTP accepted the recom - of the engine—especially at high load. If the NOx reduction efficiency were mendations of the NRC (2008) review and has adjusted its 100 percent, the engine engineers would have great leeway in improving the engine efficiency—which they currently do not have. The closer one can get aftertreatment program to address them. to this ideal the better. The objective of the research work in the 21CTP is to continually improve the NOx aftertreatment reduction efficiency at the least possible cost; thus the statement to improve performance and durability of the NOx control technology.

OCR for page 27
51 ENGINE SYSTEMS AND FUELS TABLE 3-11 Department of Energy 21CTP Supported Aftertreatment Research Programs FY 2009 FY 2010 Project Title Organization DOE Funding DOE Funding Link to Most Recent EERE Merit Review CLEERS Coordination and ORNL $200,000 $200,000 http://www1.eere.energy.gov/vehiclesandfuels/pdfs/ Joint Development of Kinetics $450,000 $500,000 merit_review_2010/emissions_control/ace022_ for LNT and SCR daw_2010_o.pdf Development of Advanced Diesel ANL $500,000 $500,000 http://www1.eere.energy.gov/vehiclesandfuels/pdfs/ Particulate Filtration (DPF) Systems merit_review_2010/emissions_control/ace024_ lee_2010_o.pdf CLEERS: Aftertreatment Modeling PNNL $750,000 $750,000 http://www1.eere.energy.gov/vehiclesandfuels/pdfs/ and Analysis merit_review_2010/emissions_control/ace023_ lee_2010_o.pdf Experimental Studies for DPF and Michigan NA $583,000 http://www1.eere.energy.gov/vehiclesandfuels/pdfs/ SCR Model, Control System, and Technological merit_review_2010/emissions_control/ace028_ OBD Development for Engines University johnson_2010_o.pdf Using Diesel and Biodiesel Fuels Combination and Integration of PNNL $200,000 $400,000 http://www1.eere.energy.gov/vehiclesandfuels/pdfs/ DPF-SCR Aftertreatment Technologies merit_review_2010/emissions_control/ace025_ rappe_2010_o.pdf Development of Optimal Catalyst University NA $637,000 http://www1.eere.energy.gov/vehiclesandfuels/pdfs/ Designs and Operating Strategies of Houston merit_review_2010/emissions_control/ace029_ for Lean NOx Reduction in Coupled harold_2010_o.pdf LNT-SCR Systems TOTAL NA $3,570,000 NOTE: Acronyms are defined in Appendix I. NA, not available. The development of effective exhaust gas aftertreatment Comment: This goal is being met through the sup- systems and the optimal integration of these technologies port of many programs discussed in this Chapter. The as part of the engine-powertrain system are a critical aspect “best” configurations are the systems developed by the of meeting the goals of the 21CTP. Of specific interest to OEMs. the 21CTP is the reduction of NOx within a lean exhaust • 21CTP Goal 5 related to aftertreatment technologies: environment and effective capture and regeneration of par- “Achieve production-feasible, life-cycle effective, ticulate matter from the exhaust stream. This happens to be emission control system(s) that will meet NOx and PM the focus of the combustion research and development com- regulations phasing in starting 2007, also with reduc- munity at large, so the 21CTP not only contributes to, but tions of unregulated “toxic” emissions.” also benefits from, the research activities of a much larger Comment: This goal was achieved, as discussed in the technical community. Health Effects section of this chapter. As part of the Phase 2 review, the DOE supplied to the • 21CTP Goal 6 related to aftertreatment technologies: committee a list of research programs that should be consid- “Research pathways to post 2010 regulations for emis- ered as part of the 21CTP. The names of these projects, the sions, such as toxics and carbon dioxide.” lead agency performing the work, their DOE funding level, Comment: The regulation for carbon dioxide emis- and a link to the most recent EERE merit review presentation sions from heavy-duty trucks will entail research into are presented in Table 3-11. pathways for meeting this regulation. For a potential The aftertreatment research projects currently supported future regulation for particulate number, research will by the 21CTP, listed in Table 3-11, cover a wide range of need to be carried out to develop an understanding technologies. Included in the funding is support for the orga- of the characteristics of the particulate number being nizational structure called Crosscut Lean Exhaust Emission emitted from future diesel combustion systems. Reduction Simulations. CLEERS, which is managed through the Oak Ridge National Laboratory, acts as a coordinating Aftertreatment Projects body and a disseminator of the newest kinetic schemes and models for aftertreatment system simulation. This is done Aftertreatment research in the 21CTP is overseen by the through its website.37 DOE, EPA, and 21CTP industry partners. Approximately $37 million has been spent for heavy-duty-truck aftertreat- ment research for the past 7 years and $3.6 million was the 37 Available at http://www.cleers.org. funding for FY 2010.

OCR for page 27
52 REVIEW OF THE 21ST CENTURY TRUCK PARTNERSHIP, SECOND REPORT More specifically, CLEERS is a collaborative effort simultaneous particulate and NOx control from the same among the national laboratories ORNL, ANL, and the Pacific device. The current focus of this work is to determine the Northwest National Laboratory (PNNL), and industry and optimal SCR catalyst loading that will maximize NOx reduc- academia; CLEERS works to identify, prioritize, and coordi- tion while minimizing the pressure drop across the DPF. nate R&D needs within industry to expedite the development These projects have several global aims: to evaluate of detailed technical data necessary to simulate lean NOx trap and address emission control technology barriers; address (LNT) and SCR. Through their efforts, LNT and SCR kinet- deficiencies in modeling capabilities and basic understand- ics have been published, the toluene poisoning mechanism ing; develop the understanding of degradation from sulfur for SCR has been identified using surface spectroscopy, and in fuels; address the high platinum metal content and high new catalyst formulations for LNTs that are more sulfur- cost; work to expand the effectiveness of catalytic systems to resistant have been developed. Most of the major catalyst a broader temperature range; eliminate the inefficient use of suppliers and engine and vehicle manufacturers participate fuel for regeneration of diesel particulate filters and desulfur- with national laboratories and academia in these activities. ization of NOx reduction systems, as well as poor reductant Within the aftertreatment program, efforts are under way utilization (lean NOx catalyst, LNC); improve inadequate at the ANL to develop advanced diesel particulate filters. sensors for processing control diagnostics; and address cost This effort involves collaboration with Corning, Caterpillar, and packaging constraints. the University of Illinois–Chicago, and the University of Finding 3-10. The research agenda of the 21CTP is focused Wisconsin–Madison; it is focused on studying the oxidation processes to enable better control systems and optimization on improving the NOx reduction performance of SCR and of regeneration strategies. LNT systems, improving the efficiency of and reducing the The PNNL is leading an effort on aftertreatment modeling fuel consumption associated with PM filter regeneration, and and analysis. This work is being done through a new CRADA improving the ability to model aftertreatment systems. The involving DOW, PACCAR, Ford, GM, and Cummins. The DOE CLEERS program does a good job of coordinating the participants are working together to enhance the scientific aftertreatment research programs within the 21CTP and dis- understanding of DPF, SCR, and LNT technologies. Recent seminating the results to the technical community at large. accomplishments include the identification of which hydro- Finding 3-11. The demands on the aftertreatment system carbons have detrimental effects to NOx reduction, why water can be an inhibitor to HC storage, and the role of the BaO/ and its performance are intimately linked to the combustion alumina interface in LNT performance with ceria as a supple- process taking place within the cylinder. Consequently, the ment. These results feed into models that are important in aftertreatment system must be developed and its performance aftertreatment design and control strategy optimization. evaluated in conjunction with the combustion system. The Under 21CTP funding, Michigan Technological Uni - 21CTP realizes this, and its new goals for the aftertreatment versity is leading an activity with Cummins, Navistar, program specifically state this. John Deere, Johnson Matthey, Watlow, ORNL, and PNNL Recommendation 3-7. The aftertreatment program within to perform an experimental assessment of DPF and SCR models. This effort is being done with diesel and biodiesel the 21CTP should be continued, and the DOE should con- fuels. The importance of particulate maldistribution within tinue to support the activities of CLEERS that interface with the DPF, NH3 loading in the SCR system, and the ability of the activities of the aftertreatment technical community at different sensors in conjunction with state estimation models large. to monitor the state of the aftertreatment system effectively Finding 3-12. Particulate size distribution is not a problem are being evaluated. Funding for a research program being led by the Uni- with current diesel-type combustion using DPFs. However, versity of Houston is exploring optimal catalyst design and as new combustion processes, possibly using different fuels operating strategies for lean NOx reduction in a coupled ranging from petroleum-derived fuels to biofuels and syn- LNT/SCR system. Participants in this program include the thetics, are integrated into future engine operating maps, it University of Kentucky’s Center for Applied Energy, Ford, is important to assess particulate size distribution character- BASF Catalysts, and ORNL. The mechanisms of NOx reduc- istics if particulate filter designs are changed or if DPFs are tion in LNT/SCR coupled systems are not understood. The not used. program participants are also exploring catalyst synthesis Recommendation 3-8. In light of the progress being made with better desulfation and durability. Recently it has been determined the non-NH3 mechanisms may be important in with new combustion technologies, which show potential SCR kinetics for Fe-zeolite systems. for very low cylinder-out NOx and particulate emissions, Finally, a research program is being led by the PNNL with the 21CTP should incorporate studies of particulate number PACCAR and DAF Trucks looking at an advanced aftertreat- emissions into their research portfolio. ment system consisting of an integrated DPF and SCR for

OCR for page 27
53 ENGINE SYSTEMS AND FUELS TABLE 3-12 Projects Attributed to Health Effects Studies Receiving Funding from the Department of Energy as Part of 21CTP FY 2009 FY 2010 Title Organization DOE Funding DOE Funding Link to Reference Advanced Collaborative Emission HEI, Lovelace $600,000 $600,000 http://www1.eere.energy.gov/vehiclesandfuels/ Study (ACES) Respiratory Research. pdfs/merit_review_2010/health_impacts/ace044_ Institute, CRC greenbaum_2010_o.pdf Measurement and Characterization ORNL $475,000 $450,000 http://www1.eere.energy.gov/vehiclesandfuels/ of Unregulated Emissions from pdfs/merit_review_2010/health_impacts/ace045_ Advanced Technologies storey_2010_o.pdf Collaborative Lubricating Oil Study NREL FY 2006-FY 2010 (DOE) http://www1.eere.energy.gov/vehiclesandfuels/ on Emissions (CLOSE Project) $892,000 pdfs/merit_review_2010/health_impacts/ace046_ lawson_2010_o.pdf NOTE: Funding levels represent DOE funds only. SOURCE: Information based on DOE Vehicle Technologies Program Merit Review (DOE, 2010b). EMISSIONS AND RELATED HEALTH EFFECTS Three main efforts are under way as part of 21CTP and the Vehicle Technologies Program to evaluate potential health Introduction concerns related to heavy-duty diesel vehicles. These efforts aim to undertake high-risk mid- to long-term research; utilize The health effects research within the 21CTP is coor- unique national laboratory expertise and facilities; help create dinated through the Health Effects Institute. The HEI is a a national consensus; and work cooperatively with industry and nonprofit corporation chartered in 1980 as an independent other agencies. The three efforts are presented in Table 3-12. research organization to provide high-quality, impartial, and relevant science on the health effects of air pollution. Project Overviews Typically the HEI receives half of its core funds from the U.S. Environmental Protection Agency and half from the Advanced Collaborative Emissions Study worldwide motor vehicle industry. The 21CTP’s support to the HEI represents a strong collaboration between the HEI, The combination of advanced-technology, compression- DOE, EPA, California Air Resources Board, Coordinat- ignition engines, aftertreatment systems, reformulated fuels, ing Research Council, Engine Manufacturers Association and oils developed to meet the 2007 and 2010 emissions (EMA), American Petroleum Institute (API), engine and standards are demonstrating reduced emissions. Substantial aftertreatment manufacturers, and lubricant suppliers. The public health benefits are expected from these reductions. objective of the research is to provide a sound scientific basis However, with any new technology it is prudent to conduct underlying any potential health hazards associated with the research to confirm benefits and to ensure that there are no use of new powertrain technologies, fuels, and lubricants in adverse impacts on public health and welfare. This is the transportation vehicles. Furthermore, the program endeavors overall objective of the Advanced Collaborative Emissions to ensure that vehicle technologies being developed by the Study (ACES) (DOE, 2010b; Greenbaum et al., 2010). DOE Vehicle Technologies Program for commercialization There are three phases to ACES: by industry will not have adverse impacts on human health through exposure to toxic particles, gases, emanation of 1. In phase 1 (completed), the Southwest Research Insti- electromagnetic fields,38 and other effects generated by these tute (SwRI) characterized emissions from four 2007 new technologies. This is being done by characterizing the engines. A final report was issued in June 2009.39 emissions from vehicles using advanced technologies and 2. In phase 2, emissions from 2010 model year engines also screening these emissions for toxicity. In selected cases are being characterized. if necessary and where possible, the team will work to iden - 3. In phase 3, health effects testing is being conducted tify the components responsible for toxicity and engineer by the Lovelace Respiratory Research Institute. In this solutions to reduce the toxic components. phase, short-term biological screening and long-term 38 The World Health Organization website includes the statement: “To date no adverse health effects from low level, long-term exposure to radio 39 Available at http://www.crcao.org/reports/recentstudies2009/ACES% frequency or power frequency fields have been confirmed but scientists are actively continuing to research this area.” Available at http://sho.int/ 20Phase%201/ACES%20Phase1%20Final%20Report%2015JUN2009. peh-emf/about/what is EMF/en.index1.htm. pdf.

OCR for page 27
54 REVIEW OF THE 21ST CENTURY TRUCK PARTNERSHIP, SECOND REPORT Collaborative Lubricating Oil Study on Emissions (CLOSE) health effects tests are being conducted on the emis- Project sions from 2007 model year engines. The objective of the CLOSE project is to quantify the The ACES project funding totals $15.5 million, with the relative contributions of fuel and engine lubricating oil to DOE contribution in FY 2009 and FY 2010 being $600,000 motor vehicle particulate matter and semi-volatile organic each year. The project will continue until mid-2013. compound emissions through the extensive chemical and To date, the reported results from the 2007 engines physical characterization of emissions under a variety of include the demonstration of emission reductions below the engine operating conditions (Eberhardt and Louison, 2010). 2007 standards as follows: PM, 89 percent below the 0.01 At the time of this review, testing from the HD compressed g/hp-h limit; CO, 98 percent below the 15.5 g/hp-h limit; natural gas and diesel buses has been completed, and detailed NMHC, 95 percent below the 0.14 g/hp-h limit; and NOx, analyses and source apportionment of exhaust from all 10 percent below the 1.2 g/hp-h average limit. Unregulated vehicle samples are now under way. emissions are 90 percent below those of a 2004 technology engine. NO2 emissions increased over those from the 2004 Response to Recommendations from NRC Phase 1 Review engines but are expected to go down in 2010; no results have been published yet. Short-term animal studies are complete, Recommendation 3-19 in the NRC (2008) Phase 1 report and a report is being prepared for review in 2011. The long- stated that the committee endorses the DOE multiparty term exposure study is under way, with results expected in effort to characterize the emissions and assess the safety and 2013. potential health effects of new, advanced engine systems, aftertreatment, fuels and lubricants (ACES), and recom- Measurement and Characterization of Unregulated mends that this continue for the remainder of the study until Emissions from Advanced Technologies results become available in the 2012-2013 time period. The DOE response to this recommendation was that it appreciates The project on the Measurement and Characterization the endorsement of the ACES program and agrees with the of Unregulated Emissions from Advanced Technologies NRC committee on its value. is largely focused on light-duty vehicles. However, some analysis of SCR systems is being done for the ACES project. Finding and Recommendation Results reported to date have included detailed particulate characterization from direct-injection spark-ignition engines Finding 3-13. The Advanced Collaborative Emissions with gasoline and ethanol blends. In addition, the HEI is Study, the Collaborative Lubricating and Oil Study on undertaking a review of the literature on ultra-fine particu - Emissions, and the project on Measurement and Character- lates (UFPs). The review will encompass information on the ization of Emissions from Advanced Technologies are com- contribution of mobile sources to atmospheric UFPs, health prehensive and cooperative projects that are investigating effects of UFPs, and the potential for environmental exposure important issues related to heavy-duty diesel engine health leading to potential health effects in humans. Animal studies effects. Based on the activities reported, the committee finds are being considered. a high degree of collaboration among government agencies, The presentation by the DOE’s James Eberhardt to national laboratories, and industry stakeholders. the committee titled “Overview of DOE Health Impacts Research” provided the following observations that may Recommendation 3-9. The DOE should continue funding indicate the need for further study:40 the Advanced Collaborative Emissions Study, the Collabora- tive Lubricating Oil Study on Emissions, and the project on • “NO2 emissions have increased significantly at two Measurement and Characterization of Unregulated Emis- sampling locations in the South Coast Air Basin since sions from Advanced Technologies until results are finalized the introduction of 2007 MY trucks. (Starting in 2007, and reported for all three studies. CARB introduced regulations to limit the increase in NO2 emissions from DPF equipped diesel engines.) HIGH-TEMPERATURE MATERIALS • Certain liquefied natural gas (LNG)-powered trucks are emitting large amounts of ammonia.” Introduction Current heavy-duty diesel engines are extremely durable, in most cases performing reliably for more than 1 mil- lion miles in Class 8 truck applications. However, modern 40 James Eberhardt, DOE, “Overview of DOE Health Impacts Research,” presentation to the committee, November 15, 2010, Washington, D.C. See diesel engines have pushed the performance of materials http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2010/ to the limit. As the 21CTP develops the next generation of health_impacts/ace00d_eberhardt_2010_o.pdf.

OCR for page 27
55 ENGINE SYSTEMS AND FUELS clean and efficient engines, new, higher-performance, light- are approaching the design limit for traditional cast iron, weight, and cost-effective materials will be needed, as well with a tensile strength of 44,000 pounds per square inch. as manufacturing and inspection methods and appropriate As cylinder pressures increase to 260 bar for engines with standards. An example of this need for materials is that the higher efficiency, midterm goals for tensile strength will be thermal efficiency of the diesel engine is enhanced with the approaching 75,000 pounds per square inch, which exceeds ability to run the engine at higher peak cylinder pressures. the 65,000 pounds per square inch tensile strength for Higher cylinder pressures and temperatures will challenge compacted graphite cast iron. Longer-term goals for tensile the current mechanical property limitations of many engine strength may approach 90,000 pounds per square inch as cylinder pressures approach 300 bar.41 components, so new materials will be needed to achieve the engines’ efficiency potential. A second example is in the potential to reduce fuel consumption through the use of fuel Propulsion Materials Programs injection systems with higher injection pressure, finer spray control, and multiple injection events. To realize these new There are a number of individual research programs in fuel injection systems, new materials with higher strength, the area of propulsion materials for both light- and heavy- duty engines.42 This work is being conducted at the ORNL, dimensional stability, and erosion resistance are needed. Lowering the rotation mass in valve trains and air-handling ANL, PNNL, and LLNL. The majority of these programs systems has the potential to improve engine response and are at the ORNL. Most are in cooperation with industrial thermal efficiency and to lower emissions. To capitalize on partners of which many of the programs are CRADAs. The these potential performance improvements, cost-effective, overall 21CTP budget for heavy vehicle propulsion materi- lightweight material with superior mechanical properties is als had averaged about $5 million for the past decade. It needed for valve train and air-handling components. After- was $4.86 million in FY 2009 and is $5.66 million in FY treatment limitations include an incomplete understanding 2010. For FY 2011, the total budget for materials for internal and optimization of catalysts, inadequate test methods for combustion engines is expected to be $8.71 million, with an rapid age testing of catalysts, and inadequate sensors for industry cost share of $5.15 million. Research areas include the following:43 process control or diagnostics. Other barriers to improved fuel efficiency are tribological limits of current lubricants. The DOE’s Heavy Vehicle Propulsion Materials Team has • Sensors, been helpful in identifying commercial materials solutions • Internal engine components, introduced in 2007 engines. A number of these materials • Friction reduction, have been identified as enablers of higher-efficiency engines • Turbomachinery, that are being developed for future engine technology. The • Fuel injection, Heavy Vehicle Propulsion Materials program has been • Alternative fuel compatibility, instrumental in developing materials technologies for future • Exhaust aftertreatment, engine technologies. • Modeling. In general, advanced material needs include the following: It is beyond the scope of this report to review each pro- • Major engine components: cost-effective materials gram individually, but a few are highlighted and listed in with higher strength and fatigue resistance (cylinder Appendix D. A complete list of 21CTP projects in the area blocks, cylinder heads, pistons, cylinder liners, cam- of high temperature materials, conducted prior to 2007, can shafts, crankshafts, bearings); be found in project quad sheets for February 2007 (ORNL, • Fuel injection systems: materials with higher strength, 2007). better dimensional stability, and erosion resistance; The DOE’s Heavy Vehicle Propulsion Materials Team • Valve train: cost-effective materials with lower recip- also has been helpful in identifying commercial materials rocating mass and greater wear resistance; solutions that were introduced in 2007 engines. CF8C- • Air-handling: corrosion-resistant materials for EGR Plus stainless steel was developed in an ORNL/Caterpillar systems; higher-strength and creep-resistant materials C RADA. CF8C-Plus steel received a U.S. patent, and for turbocharger components; Caterpillar has filed foreign patent applications to facilitate • Exhaust systems: materials with higher strength and commercial licensing. CF8C-Plus steel also received an better creep resistance (DOE, 2011a). 41 Response by 21CTP to committee question 52, Advanced Materials, As an example of advanced materials needs, cast compo- received March 1, 2011. nents such as cylinder heads and engine blocks are limited at 42 Answers submitted by the 21CTP to committee questions. peak temperature and pressure by material tensile strength. 43 Jerry Gibbs, DOE, “Materials Support for the 21st Century Truck: Current engines with a peak cylinder pressure of 190 bar Lightweighting and Propulsion Materials,” presentation to the committee, November 15, 2010, Washington, D.C.

OCR for page 27
56 REVIEW OF THE 21ST CENTURY TRUCK PARTNERSHIP, SECOND REPORT Additional information on the HTML can be found in the ASTM new-alloy designation. Caterpillar commercialized NRC (2008) Phase 1 report, Chapter 3. CF8C-Plus as the burner housing for the Caterpillar Regen- Capabilities of HTML that are of current value to the eration System (CRS) on all CAT on-highway truck engines 21CTP through the Vehicle Technologies Program’s HTML in January 2007. Deployed in the fall of 2006, more than 500 User Program include the following (DOE, 2010d):45 tons of CF8C-Plus steel have been cast to produce more than 35,000 CRS units. • The Spallation Neutron Source (SNS)—a particle The project continues in 2011 to explore thin-sections accelerator that provides neutron streams in short for turbocharger and manifold applications (Maziasz and bursts, enabling the study of materials that are not in Pollard, 2007). equilibrium and are changing dynamically; Additional examples of successful projects that led to • VULCAN—a diffractometer, which enables the inves- commercialization were presented on February 17, 2011, to committee members John Johnson and David Merrion.44 tigation of stress formation in a material as it solidifies from the molten state as an alloy component (e.g., Examples include the following: brake disk rotor, engine block); • Development of high-performance inconel, titanium, • VENUS—which makes measurements of the absorp- and silicon nitride engine valves; tion of neutrons by the various nuclei in the material. • Development of a piezoelectric control valve actuator By doping some 6Li in with the predominant 7Li iso- for fuel injectors; and tope, VENUS can create an image illustrating the flow • Exhaust aftertreatment research leading to improved of Li ions in a working Li-ion battery. Other applica- catalyst durability, improved diesel particulate filter tions of VENUS include viewing the lubricant flow in durability, and improved EGR cooler performance. a working engine. Finding 3-14. The propulsion materials program is address- During FY 2009, HTML had 11 industry participants, ing a broad range of materials issues associated with heavy- 14 university participants, and 3 national laboratory par- truck propulsion systems. Many of the initiatives are funded ticipants. Projects focused on such topics as the following: as CRADAs with significant industry cost sharing, showing strong support by industry for this area of work. • Determine the effect of machining parameters on resid- ual stress in ceramic diesel engine exhaust valves, Recommendation 3-10. The DOE should fund programs in • Study the residual stresses resulting from piercing the areas outlined in its “21CTP White Paper on Engines and truck frame rails, Fuels” (February 25, 2011) in the section “Approach to Reach- • Characterize the atomic structure of thermoelectric ing Goals” covering materials R&D for valve trains, major materials, engine components, air-handling systems (turbochargers and • Examine the plastic behavior of wrought magnesium EGR systems), and exhaust manifold sealing materials. alloys, and • Determine the mechanical and thermal properties of High Temperature Materials Laboratory fibrous diesel particulate filter materials. The High Temperature Materials Laboratory was estab- These and other projects were described in detail in a lished more than 20 years ago as a National User Facility presentation to committee members John Johnson and David to provide specialized, and, in some cases, one-of-a-kind Merrion on February 17, 2011.46 instruments for materials research and characterization. The Perhaps just as important as the direct support of the laboratory is located at the Oak Ridge National Laboratory 21CTP is the extensive benefit to the broader research and housing six centers: development community that comes from the research conducted at HTML. This research covers a wide range • Materials Analysis; of challenging problems, for which solutions require the • Mechanical Characterization and Analysis; unique instrumentation at HTML as well as the expertise of • Residual Stress; the knowledgeable DOE researchers who oversee and oper- • Thermography and Thermophysical Properties; ate the facility. The fact that many academic researchers, as • Friction, Wear, and Tribology; well as industry research specialists, seek collaboration with • Diffraction. 45 See 21CTP response to committee questions, submitted to the com - mittee on November 12, 2010. 46 Edgar Lara-Curzio, ORNL, “Materials Characterization Capabilities 44 Ron Graves, ORNL, “Material Technology for the 21st CTP Pro- at the High Temperature Materials Laboratory and HTML User Program gram,” presentation to a subgroup of the committee, February 17, 2011, Success Stories,” presentation to John Johnson and David Merrion, February Oak Ridge, Tenn. 17, 2011, Oak Ridge, Tenn.

OCR for page 27
57 ENGINE SYSTEMS AND FUELS HTML speaks to the value of the facility to the advancement BP (British Petroleum). 2011. BP Energy Outlook 2030. London, Eng- land. Available at http://www.bp.com/liveassets/bp_internet/globalbp/ of knowledge on many fronts. globalbp_uk_english/reports_and_publications/statistical_energy_ review_2008/STAGING/local_assets/2010_downloads/2030_energy_ Finding 3-15. The High Temperature Materials Laboratory outlook_booklet.pdf. Accessed May 19, 2011. continues to be a valuable resource for materials research for Brusstar, M.J., and C.L. Gray, Jr. 2007. High Efficiency with Alcohol Fuels the 21CTP, providing specialized and in many cases unique in a Stoichiometric Medium Duty Spark Ignition Engine. SAE Paper No. 2007-01-3993. instrumentation and professional expertise. The expertise of Cooper, K.R. 2004. Commercial Vehicle Aerodynamic Drag Reduction: those who oversee the laboratory, and therefore the value of Historical Perspective as a Guide. In: The Aerodynamics of Heavy HTML to all users, is enhanced by the participation of the Vehicles: Trucks, Buses, and Trains. Springer. HTML staff in the research. DOE (U.S. Department of Energy). 2006. 21st Century Truck Partner- ship Roadmap and Technical White Papers. Doc. No. 21CTP-003. December. Washington, D.C.: Office of FreedomCAR and Vehicle Recommendation 3-11. The DOE should continue to pro- Technologies. vide 21CTP researchers and other potential users access to DOE. 2009. Annual Merit Review. June. Washington, D.C: Office of Vehicle HTML, and it should make every effort to maintain support Technologies. for HTML and to maintain the cutting-edge capability of DOE. 2010a. Updated 21st Century Truck Partnership Roadmap and Techni- the facility. Moreover, the DOE should provide sufficient cal White Papers. Working draft, September 1, 2010. Washington, D.C.: Office of Vehicle Technologies. funding for HTML, and for the research specialists who DOE. 2010b. Annual Merit Review. June. Washington, D.C: Office of oversee and operate the facility, to enable continued research Vehicle Technologies. collaboration with the academic community, other govern- DOE. 2010c. Vehicle System Simulation and Testing. Multi-Year Program ment laboratories, and industry. In particular, HTML support Plan, 2011-2015. December. Washington, D.C.: Vehicle Technologies should not be reduced to a level that allows only maintenance Program. DOE. 2010d. Multi-Year Program Plan, 2011-2015. Section 2.5-3. Vehicle of the equipment for paying users. Technologies Program. December. DOE. 2011a. 21st Century Truck Partnership White Paper on Engines and Fuels. February 25. Washington, D.C.: Office of Vehicle Technologies. REFERENCES AND BIBLIOGRAPHY DOE. 2011b. National Energy Technologies Laboratory, FY2011 Vehicle Technologies Program Wide Funding Opportunity Announcement. ACEA (European Automobile Manufacturers Association). 2006. World- Funding Opportunity Number DE-FOA-0000239. Announcement Type: wide Fuel Charter, Fourth Edition, Brussels, Belgium, September. Amendment No. 000002. CFDA Number: 81086 Conservation Research Available at http://www.acea.be/index.php/files/worldwide_fuel_ and Development. Issue date: December 16, 2010. Amendment issue charter_september_2006/. date: February 2, 2011. ANL (Argonne National Laboratory). 2009. Nanofluid Development for Eberhardt, J., and D.R. Lawson. 2010. Overview of the DOE Health Im- Engine Cooling Systems. Available at http://www1.eere.energy.gov/ pacts Research. Available at http://www1.eere.energy.gov/vehiclesand vehiclesandfuels/pdfs/merit_review_2009/vehicles_and_systems_ f uels/pdfs/merit_review_2010/health_impacts/ace00d_eberhardt_ simulation/vssp_21_timofeeva.pdf. Accessed on May 5, 2011. 2010_o.pdf. ANL. 2010. CRADAs: Cooling Boiling in Head Region-PACCAR, In- EIA (Energy Information Administration). 2011a. Liquid Fuels Supply tegrated Underhood Thermal and External Aerodynamics-Cummins, and Disposition, Reference Case. Available at http://www.eia.gov/oiaf/ Routbrot. VSS004. June 8. aeo/tablebrowser/#release=AEO2011&subject=0-AEO2011&table= ANL. 2010a. Erosion of Radiator Fluids by Nanofluids. Available at http:// 11-AEO2011®ion=0-0&cases=ref2011-d020911a. www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2010/ EIA. 2011b. Light-Duty Vehicle Energy Consumption by Technology Type propulsion_materials/pm008_routbort_2010_o.pdf. Accessed on May and Fuel Type, Reference Case. Available at http://205.254.135.24/oiaf/ 5, 2011. aeo/tablebrowser/#release=AEO2011&subject=0-AEO2011&table= ANL. 2010b. Friction Modeling for Lubricated Engine and Drivetrain Compo- 47-AEO2011®ion=0-0&cases=ref2011-d020911a. nents. June. Available at http://www1.eere.energy.gov/vehiclesandfuels/ EPA (Environmental Protection Agency). 2010. Greenhouse Gas Emissions pdfs/merit_review_2010/propulsion_materials/pm026_ajayi_2010_p. Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty pdf. Accessed on June 1, 2010. Engines and Vehicles. EPA-HQ-OAR-2010-0162. NHTSA-2010-0079. ARB (Air Resources Board). Final Regulation Order to Reduce Greenhouse FRL-9219-4. November 30. Gas Emissions from Heavy-Duty Vehicles. Available at http://www.arb. EPA. 2011. SmartWay Transport Verified Technologies. Available at http:// ca.gov/regact/2008/ghghdv08/ghgfro.pdf. Accessed on May 5, 2011. www.epa.gov/smartwaylogistics/transport/what-smartway/verified- ATDynamics. 2010. Four East Coast Trucking Fleets Put TrailerTails® on technologies.htm. Accessed April 20, 2011. Tractor-Trailers to Reduce Fuel Consumption in Advance of the Holiday EPA/NHTSA (EPA/National Highway Traffic Safety Administration). 2010. Season. Available at http://www.atdynamics.com/trailertail_faq.htm. Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Accessed January 1, 2011. Medium- and Heavy-Duty Engines and Vehicles. October 25. Available Bacorsky, D., M. Dallos, and M. Worgetter. 2010. Status of 2nd Generation in Dockets No. EPA-HQ-OAR-2010-0162 and No. NHTSA-2010-0079 Biofuels Demonstration Facilities in June 2010. A report to the Interna - at http://www.regulations.gov. tional Energy Agency Bioenergy Tack 39. Available at http://www.iea. EPA/NHTSA. 2011. Greenhouse Gas Emissions Standards and Fuel Effi- org/papers/2010/second_generation_biofuels.pdf. ciency Standards for Medium- and Heavy-Duty Engines and Vehicles. Bartis, J.T., and L. von Bibber. 2011. Alternative Fuels for Military Applica- Federal Register, Vol. 76, No. 179, September 15. Available at http:// tions. Santa Monica, Calif.: RAND Corporation. www.nhtsa.gov/staticfiles/rulemaking/pdf/cafe/2011-20740.pdf . Ethanol and Biofuels News. 2010. Japan Biofuels Exist Only Because of Subsidies: Study. Vol. XXII, Issue 30. August 4. McLean,Va.: Hart Energy Publishing.

OCR for page 27
58 REVIEW OF THE 21ST CENTURY TRUCK PARTNERSHIP, SECOND REPORT Genzale, C., L.M. Pickett, and S. Kook. 2010. Liquid Penetration of Diesel NPRA (National Petroleum Refiners Association). 2010. Algae’s Potential and Biodiesel Sprays at Late-Cycle Post-Injection Conditions. SAE as a Major Fuel Producer. Paper AM-10-156. Washington, D.C. Paper 2010-04012. NRC (National Research Council). 2008. Review of the 21st Century Truck Greenbaum, D., J. Mauderly, et al. 2010. Advanced Collaborative Emis- Partnership. Washington, D.C.: The National Academies Press. sions Study (ACES). Available at h ttp://www1.eere.energy.gov/ NRC. 2010. Technologies and Approaches to Reducing the Fuel Consump - vehiclesandfuels/pdfs/merit_review_2010/health_impacts/ace044_ tion of Medium-and Heavy-Duty Vehicles. Washington, D.C.: The greenbaum_2010_o.pdf. National Academies Press. Kokjohn, S., R.M. Hanson, D. Splitter, and R.D. Reitz. 2009. Experiments ORNL (Oak Ridge National Laboratory). 2007. Propulsion Materials and Modeling of Dual-Fuel HCCI and PCCI Combustion Using In- Quad Sheets. Available at www.ornl.gov/sci/propulsionmaterials/ Cylinder Fuel Blending. SAE Paper 2009-01-2647. pdfs/21CTP_QuadSheets_2007.pdf. Accessed April 5, 2011. Kokjohn, S. R. Hanson, D. Splitter, J. Kaddatz, and R. Reitz. 2011. Fuel ORNL. 2009. Effect of Wide-Based Single Tire on Class-8 Combination Reactivity Controlled Compression Ignition (RCCI) Combustion in Fuel Efficiency. Oscar Franzese, Helmut Knee, and Lee Slezak. ORNL. Light-and Heat-duty Engines. SAE Paper 2011-01-0357. October 28. Kook, S., and Pickett, L.M. 2009. Effect of Fuel Volatility and Ignition Qual- Ra, Youngchul, R. Reitz, M. Andrie, R. Krieger, D. Foster, R. Durrett, V. ity on Combustion and Soot Formation at Fixed Premixing Conditions. Gopalakrishnan, A. Plazas, R. Peterson, and P. Szymkowicz. 2010. Study SAE Paper 2009-01-2643. of High Speed Gasoline Direct Injection Compression Ignition (GDICI) Lawson, D.R., and J. Eberhardt. 2010. Collaborative Lubricating Oil Study Engine Operation in the LTC Regime. SAE Paper 2011-01-1182. on Emissions (CLOSE Project). June 2010. Available at http://www1. Splitter, D., R. Hanson, S. Kokjohn, and R. Reitz. 2010. Reactivity Con- eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2010/health_ trolled Compression Ignition (RCCI) Heavy Duty Engine Operation at impacts/ace046_lawson_2010_o.pdf. Mid- and High-Loads with Conventional and Alternative Fuels. SAE Maziasz, P.J., and M.J. Pollard. 2007. CF8C-Plus: A New Cast Stainless Paper 2011-01-0363. Steel for High Temperature Diesel Exhaust Components. Available Stanton, D. 2010. High Efficiency Clean Combustion for Super Truck. 2010 at http://www1.eere.energy.gov/vehiclesand fuels/pdfs/deer_2007/ DEER Conference, September 29, Detroit, Mich. session9/deer07_maziasz.pdf. Accessed April 5, 2011. Sun, R., R. Thomas, and C.L. Gray, Jr. 2004. An HCCI Engine: Powerplant Mueller, C.J., A.L. Boehman, and G.C. Martin. 2009. An Experimental for a Hybrid Vehicle. SAE Paper 2004-01-0933. Investigation of the Origin of Increased NOx Emissions When Fueling Sun, H., D. Hanna, L. Hu, J. Zhang, E. Krivitzky, and C. Osborne. 2010. a Heavy-Duty Compression-Ignition Engine with Soy Biodiesel. SAE Analyses Guided Optimization of Wide Range and High Efficiency Paper 2009-01-1792. Turbocharger Compressor. DEER Conference, September 29, 2010, NAS-NAE-NRC (National Academy of Sciences-National Academy of Detroit, Mich. Engineering-National Research Council). 2009. Liquid Transportation TIAX. 2009. Assessment of Fuel Economy Technologies for Medium- and Fuels from Coal and Biomass: Technological Status, Costs, and Environ- Heavy-Duty Vehicles. Report prepared for the National Academy of mental Impacts. Washington, D.C.: The National Academies Press. Sciences by TIAX LLC, Cupertino, Calif., July 31, 2009. Navistar. 2010. Navistar Pursues Natural Gas for MaxxForce 13 Engines. UNFAO (United Nations Food and Agricultural Organization). 2010. Jat- Warrenton, Ill.: Navistar Corporation. ropha: A Smallholder Bioenergy Crop. Integrated Crop Management, Navistar. 2008. Navistar Awarded Department of Energy Funding to Vol. 8. Rome, Italy. Available at http.www.fao.org/docrop/012/i1219e/ Develop Aerodynamic Trailers. Available at http://ir.navistar.com/ i1219e.pdf. releasedetail.cfm?ReleaseID=354505. Wards. 2011. Algae-derived biodiesel fuel, Wards Auto.com, January 19, Nelson, C. 2010. Exhaust Energy Recovery—Program Summary Presenta- 2011. tion. Prepared as Final Report for Contract to Cummins. DOE DE-FC WFC (Worldwide Fuel Charter). 2006. European Automobile Manufactur- 26-05NT42419. May. ers Association, Alliance of Automobile Manufacturers Association. NESCCAF/ICCT (Northeastern States Center for a Clean Air Future/Inter- Available at http://www.jama.or.jp/eco/wwfc/pdf/WWFC_Sep2006_ national Council on Clean Transportation). 2008. Reducing Heavy-Duty Brochure.pdf. Long Haul Combination Truck Fuel Consumption and CO2 Emissions. Wijffels, H., and M.J. Barbosa. 2010. An Outlook on Microalgal Biofuels. P. Miller, ed. October 28. Science, Vol. 329, No. 5993, Pages 796-799. New York Times. 2010. DOE’s National Algae Biofuels Technology Road- map, June 29, 2010.