Home > Alternative Fuels > Alternatives to Traditional Transportation Fuels 1994 > Introduction Alternatives to Traditional Transportation Fuels 1994 Volume 2 Greenhouse Gas Emissions 1. Introduction This report addresses the Energy Information Administration's (EIA's) efforts to fulfill its reporting obligations under Section 503 (a)(4) and (b)(3) of the Energy Policy Act of 1992 (EPACT) [14] regarding alternative transportation fuels [15] and replacement fuels [16]. These provisions authorize EIA to collect and report information on greenhouse gases emitted by use of replacement fuels, which is the subject of this publication. The full text of Section 503 is as follows: Section 503. Replacement Fuel Demand Estimates and Supply Information (a) ESTIMATES--Not later than October 1, 1993 [17], and annually thereafter, the Secretary [of Energy], in consultation with the [EIA] Administrator, the Secretary of Transportation, and other appropriate State and Federal officials, shall estimate for the following calendar year-- (1) the number of each type of alternative fueled vehicle likely to be in use in the United States; (2) the probable geographic distribution of such vehicles; (3) the amount and distribution of each type of replacement fuels; and (4) the greenhouse gas emissions likely to result from replacement fuel use. (b) INFORMATION--Beginning on October 1, 1994 [18], the Secretary shall annually require-- (1) fuel suppliers to report to the Secretary on the amount of each type of replacement fuel that such supplier-- (A) has supplied in the previous calendar year; and (B) plans to supply the following calendar year; (2) suppliers of alternative fueled vehicles to report to the Secretary on the number of each type of alternative fueled vehicle that such supplier-- (A) has made available in the previous calendar year; and (B) plans to make available for the following calendar year; and (3) [fuel suppliers] to provide the Secretary information necessary to determine the greenhouse gas emissions from the replacement fuels used, taking into account the entire fuel cycle. (c) PROTECTION OF INFORMATION.--Information provided to the Secretary under subsection (b) shall be subject to applicable provisions of law protecting the confidentiality of trade secrets and business and financial information, including section 1905 of Title 18, United States Code. In 1994, EIA implemented its first EPACT data collection program and released the required information in Alternatives to Traditional Transportation Fuels: An Overview (DOE/EIA-0585/O). In 1995, the agency published Alternatives to Traditional Transportation Fuels 1993 (DOE/EIA-0585/93). Also in 1995, EIA delivered its analysis of the greenhouse gases (GHGs) from alternative transportation fuel use in a presentation at an international conference on the emissions inventory sponsored by the U.S. Environmental Protection Agency in Raleigh, North Carolina [19]. In February 1996, Volume 1 of Alternatives to Traditional Transportation Fuels 1994 (DOE/EIA-0585/94) presented data on alternative-fueled vehicles and alternative transportation fuels (ATFs). EIA had previously released the required information by placing data tables on the EIA Electronic Publishing System (EPUB). Now, Volume 2 of that report compiles the greenhouse gas emission results, based on information currently available. Section 503 (a)(4) and (b)(3) require estimations of GHG emissions resulting from alternative transportation fuels that take the entire fuel cycle into account. After reviewing numerous studies, EIA decided that an approach proposed by Dr. Mark Delucchi [20] was best suited to supply the required information. This model is reasonably comprehensive and detailed in its methodology for estimating transportation fuel GHG emissions. EIA continues to modify it to provide all required emissions information for each alternative fuel [21]. Global warming due to anthropogenic (i.e., human-based) GHGs is a controversial issue. EIA, therefore, considers it important to increase public understanding of this complex topic as well as to satisfy the reporting requirements of EPACT Section 503. Chapter 2 gives an overview of the greenhouse effect. Using available data, Chapter 3 presents EIA's analysis of total fuel cycle emissions of GHGs for gasoline, compressed natural gas (CNG), liquefied petroleum gas (LPG) from oil and gas, methanol from natural gas, and ethanol from corn. EIA's analysis produced several major conclusions. One was that while CNG produces the lowest level of carbon dioxide emissions across the total fuel cycle (followed closely by LPG and ethanol from corn), it produces the largest methane emissions across the total fuel cycle (Figure 1 and Table 1). In addition, there are probably minimal, if any, reductions in weighted GHG emissions from alternative transportation fuels for the entire fuel cycle, except for LPG if water vapor is taken into account [22]. However, it is currently believed that water vapor produced from surface sources such as the transportation fuel cycle, makes a minimal impact on atmospheric water vapor concentrations. EIA also concluded that ethanol from corn produces the largest nitrous oxide emissions across the total fuel cycle (Table 1). D Table 1. Total Fuel Cycle Greenhouse Gas Emissions From Gasoline and Alternative Transportation Fuels Greenhouse Gas Gasoline Methanol From Natural Gas Ethanol From Corn Compressed Natural Gas Liquefied Petroleum Gas Unweighted Quantities Carbon Dioxide (CO2) 7,900 8,700 7,400 5,640 6,000 Water Vapor (H2O) 7,750 16,230 17,280 10,930 8,180 Methane (CH4) 22 34.6 39.3 91.3 17.2 Nitrous Oxide (N2O) 1.7 1.7 9.3 1.6 1.6 Nitrogen Oxides (NOx) 26.5 36.2 58.3 24.2 22.9 Carbon Monoxide (CO) 330.4 327.1 258.25 324.2 325 Weighted Quantities Carbon Dioxide (CO2) 7.9 8.7 7.4 5.64 6 Water Vapor (H2O)a NA NA NA NA NA Methane (CH4) 0.22 0.35 0.39 0.91 0.17 Nitrous Oxide (N2O) 0.54 0.54 2.98 0.54 0.54 Nitrogen Oxides (NOx) 1.06 1.45 2.33 0.97 0.92 Carbon Monoxide (CO) 0.99 0.98 0.78 0.97 0.98 Totalb 10.71 12.02 13.88 9.03 8.61 aGlobal warming potential value for water vapor has not been determined by the Intergovernmental Panel on Climate Change. bTotal weighted greenhouse gas (GHG) emissions do not include contributions from water vapor. NA = Not applicable because the Intergovernmental Panel on Climate Change has not issued a global warming potential for water vapor. Notes: • Unweighted GHG emissions are in millimoles per vehicle mile traveled (VMT). One mole of a gas is equal to the amount of substance that contains as many elementary units (6.023 x 1023 molecules or atoms) as there are atoms in 12 grams of carbon-12. Normally, emissions are reported in grams per VMT. However, reporting in moles is preferable because greenhouse gas heat absorption is directly related to the number of molecules of a gas. Weighted GHG emissions are shown in moles of CO2 equivalent per VMT equal to the unweighted quantity multiplied by the global warming potential per mole of each gas, relative to carbon dioxide. • Gasoline refers to conventional unleaded gasoline in this report. • VMT estimate derived assuming a vehicle with gasoline efficiency of 30 miles per gallon. • Emissions from vehicle manufacturing are not included. • Nitrogen oxides include primarily nitric oxide and nitrogen dioxide. Sources: Unweighted: Derived from greenhouse gas emissions spreadsheet provided to the Energy Information Administration, July 1994. The spreadsheet is an unpublished revision of a report from the Argonne National Laboratory, Center for Transportation Research, Emissions of Greenhouse Gases from the Use of Transportation Fuels and Electricity, ANL/ESD/TM-22, prepared by Dr. Mark Delucchi, Vol. 1 (Argonne, IL, November 1991) and Vol. 2 (Argonne, IL, November 1993). Also see Energy Information Administration, Alternatives to Traditional Transportation Fuels 1993, EIA/DOE-0585(93) (Washington, DC, January 1995); and Decision Analysis Corp., “Measurement of Emissions: Greenhouse Gas Estimates for Alternative Transportation Fuels,” unpublished final report prepared for the Energy Information Administration (Vienna, VA, December, 1995). Weighted: High global warming potential values per mole (relative contribution in 100 years) found in Table 5 are used. Global warming potential values for nitrogen oxides and carbon monoxide of 40 and 3 per mole, respectively, are found in Argonne National Laboratory Center for Transportation Research, “Development and Use of GREET Model to Estimate Fuel Cycle Energy Use and Emissions of Various Transportation Technologies and Fuels,” ANLIESD-31, prepared by Michael Q. Wang (Argonne, IL, March 1996), and Decision Analysis Corp., “Measurement of Emissions: Greenhouse Gas Estimates for Alternative Transportation Fuels,” unpublished final report prepared for the Energy Information Administration (Vienna, VA, December 1995). Proceed to Chapter 2 Appendix A contains an overview of global warming, including GWP, radiative forcing, albedo, and vertical mixing concepts. It also discusses the present status of global climate models and community climate models, which include the latest findings on clouds' unexpected four-fold absorption of short-wave radiation. Appendix B discusses the factors involved in ozone stability in the atmosphere. Appendix C discusses the combustion chemistry of alternative and traditional transportation fuels. Appendix D describes the spectral overlaps of greenhouse gases and their significance in terms of the greenhouse effect and global warming.