America is addicted to oil, which is often imported from unstable parts of the world. The way to break this addiction is through technology…. New technologies will help us reach another great goal: to replace more than 75 percent of our oil imports from the Middle East by 2025.
President George W. Bush
January 31, 2006
State of the Union Address
Our nation’s dependence on imported oil leaves it dangerously vulnerable to attack. A single well-designed attack on the petroleum infrastructure in the Middle East could send oil to well over $100 per barrel and devastate the world’s economy. Schultz and Woolsey (2005) analyzed this vulnerability in a paper entitled “The petroleum bomb.” As shown in Figure 1-1, the U.S. dependency on foreign oil is expected grow to 70 percent by 2025, and Figure 1-3 shows that the nonfighter aircraft in the Air Force inventory consume 69.9 percent (approximately 1.82 billion gal/yr) of DoD aviation fuel. From mid-2004 to mid-2006, the cost of jet fuel increased from approximately $1/gal to $2.53/gal, a significant extra cost burden. These two key factors led to the creation of the Assured Fuels Initiative in the Office of the Secretary of Defense (OSD). The initiative has the following mission:
to catalyze the commercial industry to produce clean liquid fuels for the military from secure domestic resources using environmentally sensitive processes to enable a bridge to the future. (Sega, 2006)
DoD and the Department of Energy (DOE) are working jointly to develop national initiatives to produce, test, certify, and use alternative, or synthetic, jet fuel. On May 30, 2006, the Commerce Business Daily reported that the Defense Energy Support Center (DESC) was seeking industry proposals to supply 200 million gallons of alternative, or synthetic, Fischer-Tropsch (FT) fuel for the Air Force and Navy to conduct major vehicle and vessel field tests in 2008-2009 as part of a broader effort to reduce dependence on foreign oil and greenhouse gas emissions.
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Improving the Efficiency of Engines for Large Nonfighter Aircraft 7 Alternative Fuels BACKGROUND America is addicted to oil, which is often imported from unstable parts of the world. The way to break this addiction is through technology…. New technologies will help us reach another great goal: to replace more than 75 percent of our oil imports from the Middle East by 2025. President George W. Bush January 31, 2006 State of the Union Address Our nation’s dependence on imported oil leaves it dangerously vulnerable to attack. A single well-designed attack on the petroleum infrastructure in the Middle East could send oil to well over $100 per barrel and devastate the world’s economy. Schultz and Woolsey (2005) analyzed this vulnerability in a paper entitled “The petroleum bomb.” As shown in Figure 1-1, the U.S. dependency on foreign oil is expected grow to 70 percent by 2025, and Figure 1-3 shows that the nonfighter aircraft in the Air Force inventory consume 69.9 percent (approximately 1.82 billion gal/yr) of DoD aviation fuel. From mid-2004 to mid-2006, the cost of jet fuel increased from approximately $1/gal to $2.53/gal, a significant extra cost burden. These two key factors led to the creation of the Assured Fuels Initiative in the Office of the Secretary of Defense (OSD). The initiative has the following mission: to catalyze the commercial industry to produce clean liquid fuels for the military from secure domestic resources using environmentally sensitive processes to enable a bridge to the future. (Sega, 2006) DoD and the Department of Energy (DOE) are working jointly to develop national initiatives to produce, test, certify, and use alternative, or synthetic, jet fuel. On May 30, 2006, the Commerce Business Daily reported that the Defense Energy Support Center (DESC) was seeking industry proposals to supply 200 million gallons of alternative, or synthetic, Fischer-Tropsch (FT) fuel for the Air Force and Navy to conduct major vehicle and vessel field tests in 2008-2009 as part of a broader effort to reduce dependence on foreign oil and greenhouse gas emissions.
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Improving the Efficiency of Engines for Large Nonfighter Aircraft Specifically, the DESC request for information (RFI) seeks to identify potential suppliers of synthetic fuel for aviation that meets the FT draft synthetic fuel specification for delivery to various Air Force and Navy installations for multiple weapon systems testing and subsequent use. DoD is investigating the feasibility of supplying aviation synthetic fuel requirements of up to 200 million U.S. gallons, or any portion thereof, during calendar year 2008, with 100 million gallons meeting the JP-8 flashpoint of 38°C and 100 million gallons meeting the JP-5 flashpoint of 60°C. Further, DoD is interested in long-term prospects for the manufacture and supply of aviation synthetic fuels in increasing quantities, with an emphasis on domestic industrial capability and feedstocks. This request is an essential step in determining market interest in the manufacture and supply of aviation synthetic fuel. Interested parties have been asked to provide the following information: (1) ability to meet the draft specification; (2) current and future yearly production capability in the continental United States (CONUS) and outside the continental United States (OCONUS); (3) location of the production facility; (4) quantity that can be produced and when it can be made available; (5) type and location of feedstocks to be used in the production of aviation synthetic fuel; (6) capability and experience in the sale and delivery of aviation synthetic fuel; (7) distribution methods available from the production facility; (8) whether delivery can be made on a free on board (FOB) destination basis (preferred method) or FOB origin basis; (9) financial ability to justify potential award of a supply-type contract; (10) estimated start-up cost to begin production of aviation synthetic fuel (specify scale of production); (11) estimated cost, variable and fixed, of producing a gallon of fuel; and (12) understanding of federal, state, and local environmental laws and regulations, and familiarity and experience with environmental compliance procedures and regulations for applicable states and U.S. Environmental Protection Agency (EPA) regions. In addition, interested parties should provide comments on the nature and level of federal and state incentives and/or obligations (e.g., R&D, capital investment, investment or production incentives) needed to develop and sustain long-term domestic commitments to producing aviation synthetic fuels. As of this writing DESC has received an overwhelming response to its RFI from the industry. This would appear to augur well for the production of alternative fuels by the industry, because DoD is the single largest buyer of jet fuel in the country. Also, military logistics and national security should take precedence, and it remains to be seen just how the use of synthetic fuels will affect the fuel interchangeability, airframe compatibility, fuel efficiency, and engine operability of re-engined aircraft. Specifically, the FT fuel must be fully interchangeable with JP-8 fuel, and switching from one to the other must not cause any adverse effects. In April 2006, under the provision of the Energy Policy Act of 2005 (P.L. 109-58), the Senate Energy Committee discussed the creation of technology for coal-to-liquid (CTL) fuel. The effort would comprise loan guarantees for building CTL plants producing over 10,000 bbl/day, up to $20 million in matching loan guarantees for large-scale CTL plants, and investment tax credits and expensing capped at $200 million. Thus, DOE has comprehensive plans to create a domestic CTL infrastructure. SYNTHETIC FUEL PROPERTIES, SPECIFICATIONS, AND RE-ENGINING Fuels for the military may not be sold into the commercial sector unless they meet certain specifications that are usually developed by a consortium of industry experts. For example, in the United States, the American Society of Testing and Materials (ASTM) International Committee D2 is in charge of development and modifications of ASTM D 1655, which contains the specifications for the commercial jet fuels Jet A and Jet A-1. Military standards are “owned” by the relevant organization, for example, the Air Force Petroleum Office is responsible for MIL-DTL-83133E, which specifies the properties of fuels to be purchased as JP-8 and JP-8+100. These specifications typically require that fuels be derived
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Improving the Efficiency of Engines for Large Nonfighter Aircraft from petroleum distillate products. Thus, the commercialization of synthetic fuels produced from coal or other carbon sources such as natural gas or biomass via the FT process or any other process will not be possible until these standards are modified to allow the use of synthetic fuels produced by the military. Fortunately, much has been done in recent years to pave the way for synthetic fuels. The British Defense Standard DEF-STAN 91-91 was recently modified to allow the commercial use of 50:50 mixtures of synthetic fuels produced from coal and petroleum-derived jet fuels produced by Sasol Ltd. (South Africa). An effort is under way to permit use of fully synthetic jet fuel produced by that company. In addition, DoD, led by the Air Force Research Laboratory (AFRL), is in the process of formulating a standard to allow the use of synthetic fuels in military aircraft. The fuel properties of interest are these: API gravity and conductivity, Chemical composition, Thermal stability, Low-temperature properties (freeze point and viscosity), Elastomer swell, Fuel lubricity, and Combustion properties. Recently, Harrison and Zabarnick (2006) reported on preliminary studies of the measured properties and behavior of synthetic FT-based jet fuels and compared them with conventional JP-8 fuel. Below is a brief description of their results. Gravity and conductivity. Fuel density affects the aircraft range and hence the flight mission capability. The FT fuel sample was 5 percent less dense than JP-8 fuel owing to the absence of high-density (~0.87 g/mL) aromatic compounds that are present in conventional petroleum fuels. Thus, blending the FT fuel with aromatic compounds will increase its density. For volume-limited aircraft, FT fuels may slightly decrease range, although some of the impact is offset by the higher gravimetric heating value of FT fuels. For weight-limited aircraft, some small benefits may be gained. In the aggregate, there is no adverse or beneficial effect on airplane configuration or fuel efficiency. If the standard JP-8 additive package (static dissipater, icing inhibitor, and corrosion inhibitor) is used, the FT fuel passes the specification test for conductivity. Chemical composition. Using ASTM D2425-93, Hydrocarbon Analysis Using Mass Spectrometer, it was found that typical JP-8 fuel samples contained approximately 60 percent paraffins, 20 percent cycloparaffins, and 20 percent aromatics. In contrast, the FT fuel samples contain mostly the same n- and isoparaffins as JP-8 but less than 1 percent cycloparaffins and aromatics. During combustion, the absence of aromatic compounds reduces the formation of polycyclic aromatic hydrocarbon (PAH) soot precursors. Also, synthetic FT fuels contain undetectable levels of heteroatomic polar species such as phenols (<15 mg/L) as compared with 100-600 mg/L in petroleum-derived fuels. This fuel property provides FT fuels with a high level of thermal stability. Thermal stability. This property refers to the ability of a fuel to resist formation of surface and bulk deposits upon exposure to elevated temperatures. High-thermal-stability fuels can be used as effective heat sinks for the thermal management of aircraft and engine components. Tests conducted at 140°C for 15 hr (oxidative stability) showed that petroleum-derived fuel deposited ~2 to 8 µg/cm2; in contrast, synthetic FT fuels deposited ~1.5 µg/cm2. Low-temperature properties. During high-altitude, long-duration (i.e., loitering) flight, jet fuel in the tank can approach very low ambient temperatures (<40°C). Thus, flowability, freeze point, and viscosity (for atomization) become important properties. The freeze point of synthetic
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Improving the Efficiency of Engines for Large Nonfighter Aircraft FT fuel was found to be as low as −59°C, well below the JP-8 specification of ≤−47°C. The FT fuel samples displayed a more gradual rise in dynamic viscosity than the petroleum-derived fuels, whose viscosity rose sharply. Also, the kinematic viscosity of FT fuels, although slightly higher than that of JP-8 fuel, was still well below the specification maximum viscosity, for JP-8, of 8 centistokes (cSt) at −20°C and, for Jet Propulsion Thermally Stable (JPTS), 12 cSt at −40°C. Elastomer swell. Most aircraft fuel system seals swell when exposed to fuel, especially to the aromatic and polar species (such as phenols and glycol-based fuel system icing inhibitors) present in petroleum-derived fuels. Graham et al. (2006) found that nitrile O-rings soaked in FT fuels showed very little swelling (<2 percent), whereas those soaked in JP-8 fuel swelled by approximately 16 percent. Thus, the nitrile swell characteristics of FT fuel can be improved by additives that increase swell, blending with petroleum-derived fuels, or the addition of aromatic species to prevent fuel system leaks. Fuel lubricity. Lubricity permits trouble-free operation of fuel delivery system components such as fuel pumps and flow-control valves. The JP-8 fuel specification calls for the addition of a corrosion inhibitor, which also improves fuel lubricity. Tests based on ASTM D 5001, Ball-on-Cylinder Lubricity Evaluator (BOCLE), showed wear scars with FT fuels over the range 0.82 to 0.88 mm as compared with a maximum wear scar of 0.85 mm for Jet A-1 fuel. Clearly, FT fuels exhibit borderline lubricity, and corrosion inhibitor/lubricity improver additives are required to improve fuel lubricity. Combustion properties. Emissions of soot and NOx from combustion are important properties. Although DoD aircraft are exempt from some EPA regulations, there are potential conflicts with European Union rules, which might limit tanker deployment. Evaluations of soot emissions from FT fuels, FT/JP-8 blends, and JP-8 were performed using a T63-A-7000 turboshaft engine. Results showed reduced particulate emissions for both idle and cruise conditions. The reduction was attributed to reduced aromatic concentration, which reduces PAH (soot nuclei precursors) formation during combustion. Finally, no changes in NOx emissions were observed. Finding 7-1. Alternative fuels have properties that have substantial advantages over conventional fuels in areas of thermal stability, low-temperature operability, and soot emissions. However, two properties—elastomer swell and lubricity—may need to be modified. Detailed data on fuel properties are lacking. Recommendation 7-1. The committee recommends that the Air Force Office of Scientific Research and/or the AFRL should initiate a comprehensive program of fundamental research covering FY08 to FY15 with an annual budget of $5 million. The goal of this program should be to study properties of surrogate fuels, synthetic fuel CTL process technologies, synthetic fuels produced from a variety of feedstocks (such as coal, oil shale, and biomass), and synthetic–conventional fuel blends. Systematic molecular and chemical kinetics modeling studies should be performed to establish a fundamental database of fuel and combustion properties. This level of funding is urgently required to develop cooperative research programs (such as the Multidisciplinary University Research Initiative) throughout the nation. CHALLENGES TO PRODUCING DOMESTIC ALTERNATIVE FUELS Congress has requested a development plan from DOE to facilitate the production of liquid fuels from coal (P.L. 109-163, Section 1090). It is estimated that domestic energy sources (coal, shale, renewables,
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Improving the Efficiency of Engines for Large Nonfighter Aircraft and alternative sources) have more than three times as much potential as estimated Middle East reserves. These fuels have not come into widespread commercial use in the United States, partly because of their cost; however, with rising petroleum cost and increased production volume, some alternative fuels are beginning to look competitive, and technology is improving. The fact that Sasol in South Africa, with FT fuel, and others in Canada, with tar sands, are in production is promising. Now, the challenge is to develop these domestic resources in partnership with other government agencies and private industry. Economic barriers include uncertainties surrounding the price of oil, high capital and operating costs, and investment risks. Environmental barriers include the carbon dioxide (CO2) produced during the preparation of synthesis gas for the FT process and the expansion of coal refining, processing, and production. Barriers to commercial deployment include competition for process equipment, the scarcity of engineering skills, and the transportation of feedstock to the processing location. Finding 7-2. As shown in Figure 7-1, industry needs DoD leadership to bridge the Valley of Death and to obtain secure domestic sources of fuel. In October 2005, DoD established the Energy Senior Focus Group, whose chair is the Secretary of the Air Force (SAF/US), and has since published OSD guidance on energy policy. An Air Force energy document (Sega, 2006) describes the near- and mid-term acquisition and technology strategy as follows: Alternative Fuels Initiative (coal, natural gas, oil shale, and biomass), Aircraft Technology Initiative (VAATE engines and ultralightweight aircraft structures), and Modernization Initiative (re-engining studies for improved air vehicle efficiency). Recommendation 7-2. The Alternative Fuels Initiative should have as its primary goal the creation of a domestic synthetic fuels industry. FIGURE 7-1 DoD leadership required to bridge the Valley of Death. SOURCE: Harrison (2006).
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Improving the Efficiency of Engines for Large Nonfighter Aircraft FIGURE 7-2 Suggested two-tiered approach for developing a domestic synthetic fuels industry. SOURCE: Personal communication from Steven Zabarnick, Distinguished Research Chemist, University of Dayton Research Institute, to committee member Dilip Ballal on September 1, 2006. This goal should be pursued by two parallel pathways, as shown in Figure 7-2: (1) creation of subscale facilities to confirm the viability of the synthetic fuels processes and procedures, as well as to build an experience base in their operation, and (2) a simultaneous R&D effort directed at improving efficiency, economic viability, and product properties in these subscale facilities.1 It is essential to both build the subscale facilities and perform the R&D work to establish the knowledge base and optimize the operating variables for the creation of full-scale plants. The results of the R&D work will be closely applied to operating facilities to ensure that these efforts are both useful and relevant. Finding 7-3. The Alternative Fuels Initiative has already called for procuring 100,000 gallons of natural gas FT synthetic fuel in FY06 to conduct B-52 flight demonstration tests and to finalize cost/benefit modeling with DOE. As the fuel is certified for military aviation use and logistics and handling experience is gained, more fuel will be needed. Thus, in June 2006, DESC issued an RFI to seek industry proposals to supply 200 million gallons of alternative fuel from domestic sources to reduce foreign oil dependence and greenhouse gas emissions. Recommendation 7-3. DoD, through the AFRL, should commit to building an assured aerospace fuels research facility (AAFRF) that would perform R&D essential to the development of CTL synthetic fuel technology. Such a facility could comprise a modular research-scale pilot facility to test different catalysts, coal contaminants (mercury and sulfur), syngas cleanup, syngas and CTL fuel yield optimization, control over the quality of jet fuels, fuels test equipment, and combustion burners for emissions testing. This effort should be funded at $7 million/yr over FY08-FY15. The AAFRF will be a national resource: It will test fuels procured by DESC and build a database of fuel 1 Personal communication from Steven Zabarnick, Distinguished Research Chemist, University of Dayton Research Institute, to committee member Dilip Ballal on September 1, 2006.
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Improving the Efficiency of Engines for Large Nonfighter Aircraft properties and fuel specifications for certification. It will also serve as a research tool for professional researchers from government, academia, and industry as well as a training ground for skilled operators, technicians, and researchers for future commercial facilities. Finding 7-4. Synthetic fuels and the creation of an industry to make and distribute them offer numerous advantages. Synthetic fuels produced via the FT process are inherently clean. The fuel produced contains significantly less sulfur (<1 ppm) than any other proposed low-sulfur fuels, such as ultra-low-sulfur diesel (<15 ppm) and low-sulfur diesel (<50 ppm). Thus, FT fuels could potentially be used directly as high-value diesel while producing no environmentally detrimental sulfur oxides and less particulates upon combustion (Norton et al., 1998). In addition, FT fuels have the important advantage of being fungible with the current transport/pipeline infrastructure. Creation of a synthetic fuels industry will create a significant number of jobs in many areas, including mining, engineering, and transportation. DoD is currently studying a jet fuel specification that would allow the use of synthetic fuels produced by the FT process. Sasol Ltd. of South Africa has produced synthetic aviation fuel for commercial use for many years, demonstrating a viable market in the public sector. Fuel produced via the FT process could be used directly as a diesel fuel or upgraded using extant processing techniques to form gasoline; both uses promise growing markets. Synthetic fuel feedstocks include coal, oil shale, and biomass. Recommendation 7-4. DoD should take steps beyond the B-52 flight demonstration to reaffirm its long-term commitment to synthetic fuels for its fleet of aircraft. This includes qualifying an FT fuel specification and fully certifying aircraft re-engined with, for example, CFM56 and large tanker platforms such as the KC-135R/T, C-130, and KC-10. Finding 7-5. A number of government incentives are either in place or have been proposed to encourage development of a domestic CTL industry. Rep. John Shimkus (R-Ill.) introduced a House bill in May 2006 to extend a $0.50 per gallon tax credit originally slated for ethanol and biodiesel fuels to alternative fuels produced from coal. The bill would also extend the deadline for these credits from 2009 to 2020. The Energy Policy Act of 2005 contains investment tax credits for advanced coal and industrial gasification projects. Recent government initiatives could raise the current industrial gasification investment tax credit from the current $350 million to $850 million. Recommendation 7-5. DoD, as the single largest buyer of jet fuels in the nation, should consider other incentives such as floor price guarantees for jet fuels produced to assure an acceptable rate of return, loan guarantees to allow private financing under reasonable terms, additional tax incentives such as investment tax credits, fuel excise tax exemptions, and/or accelerated depreciation. STRATEGY FOR QUALIFYING ALTERNATIVE FUELS Finding 7-6. A systematic, centralized fuel certification process is needed. This includes not only R&D but also fuel blending, handling, storage, and transportation issues. Also, over the years the number of conventional fuels on the battlefield has swollen from about 6 (in the 1990s) to 10 (today), and this number is expected to grow to over 12 by 2010. The unique properties of synthetic fuels promise to turn the idea of a single fuel for the battlefield into a reality, greatly simplifying battlefield
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Improving the Efficiency of Engines for Large Nonfighter Aircraft FIGURE 7-3 Candidate synthetic fuels qualification strategy. SOURCE: Harrison (2006). logistics. Their low emissions and high thermal stability makes them ideal for replacing JP-8 and Jet A-1 in aircraft, high cetane number (>74) allows their use in army and marine ground vehicles, and the absence of sulfur and aromatics could enable their use as hydrocarbon reformers for fuel cell power generation. These domestically produced fuels represent a quantum leap in simplifying logistics and decreasing our dependence on foreign oil. Recommendation 7-6. DoD should, over the period FY08-FY15, put into place a comprehensive program of candidate fuel qualification strategy comprising four phases: R&D, system demonstration, transition and deployment, and operations and support (see Figure 7-3). This work should be funded at $15 million per year. COAL-TO-LIQUID FUEL TECHNOLOGY PROMOTION ACT In May 2006, Senators Bunning, R-Ky., and Obama, D-Ill., introduced S.3325, Coal-to-Liquid Fuel Promotion Act of 2006. If passed, this legislation will help create the infrastructure needed to make CTL a viable domestic energy source.2 In the CTL process, coal is gasified, the gas is run through the FT process, and the resulting fuel is refined into an environment-friendly diesel fuel that has no sulfur or nitrogen. With a heavy investment in CTL, the United States will wean itself from foreign sources of energy and at the same time create jobs. The CTL legislation has three parts: (1) loan guarantees for construction and planning of CTL plants, (2) expansion of current investment tax credits and expensing 2 As of January 23, 2007, S.3325 has not been enacted into law. More information can be found at http://thomas.loc.gov/cgi-bin/bdquery/z?d109:s.03325:. Last accessed on January 23, 2007.
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Improving the Efficiency of Engines for Large Nonfighter Aircraft provisions and extension of the fuel excise tax credit (from 2009 to 2020), and (3) funding for DoD to purchase, test, and integrate these fuels into the Strategic Petroleum Reserve (SPR) for national security and defense. Specifically, it authorizes the construction of SPR storage facilities for CTL fuel away from states bordering the Gulf of Mexico. Finding 7-7. The CTL Fuel Promotion Act of 2006 authorizes DoD to hold up to 20 percent of the SPR in the form of CTL finished fuels. It also gives DoD multiyear contracting authority for up to 25 years and authorizes funding for the Air Force CTL R&D and testing program. SUMMARY This chapter addresses fuel properties and specifications and their impact on re-engining; challenges for the domestic production of alternative fuels; and a strategy for qualifying alternative fuels. Many properties of alternative fuels have substantial advantages over conventional fuels, and the unique properties of synthetic fuels may bring DoD closer to the single battlefield fuel concept, greatly simplifying the logistics of battle. Detailed data on fuel properties and fundamental knowledge of fuel combustion are lacking. Domestic energy sources (coal, shale, renewables, and alternative sources) have more than three times as much potential as estimated Middle East reserves. The challenge remains to develop these resources in partnership with other government agencies and private industry. Economic barriers, environmental barriers, and barriers to commercial deployment must be overcome, and the industry needs DoD leadership to bridge the gap between technology development and deployment. A systematic, centralized fuel certification process is needed. This includes not only R&D but also fuel blending, handling, storage, and transportation issues. The unique properties of synthetic fuels allow their use by all the services. These domestically produced fuels represent a quantum leap in simplifying logistics and decreasing our nation’s dependence on foreign oil. REFERENCES Published Graham, J.L., R.C. Striebich, K.J. Myers, D.K. Minus, and W.E. Harrison, III. 2006. Swelling of nitrile rubber by selected aromatics blended in a synthetic jet fuel. Energy & Fuels 20: 759-765. Harrison, W.E., III, and S. Zabarnick. 2006. The OSD Assured Fuels Initiative—Military fuels produced from coal. A paper presented at the DOE Coal Conference, Clearwater, Fla. March. Norton, P., K. Vertin, B. Bailey, N.N. Clark, D.W. Lyons, S. Goguen, and J. Eberhart. 1998. Emissions from trucks using Fischer-Tropsch diesel fuel. SAE Paper 982526. Schultz, G.P., and R.J. Woolsey. 2005: The petroleum bomb. Mechanical Engineering: 28-34. New York, N.Y: American Society of Mechanical Engineers. Sega, Ron. 2006. Air Force Energy Strategy. Washington, D.C.: U.S. Air Force. April 19. Unpublished William Harrison, Director, National Aerospace Fuels Research Complex, Air Force Research Laboratory, “Alternative fuels overview,” Presentation to the committee on June 13, 2006.