Fuel Properties: Notes and Sources
There are several things to keep in mind when viewing fuel properties tables. This page outlines general and specific notes, as well as source material. General notes apply to all tables, while specific notes, which are marked with numbers, apply to special circumstances. Source materials for the tables are marked by letters below.
General Notes
The goal of listing fuel properties and attributes in customized tables is to address questions commonly asked when comparing and choosing fuels. Values are stated in units most commonly used in the United States.
Actual energy content and other properties for specific fuels can vary by region around the country (and the world). They also vary over time as fuel mixes and feedstocks change.
State and local departments of weights and measures and tax revenue agencies (including the Internal Revenue Service) may have other values that must be used for official tax calculations or commerce and trade purposes.
These tables cite heating values collected and averaged by Argonne National Laboratory for its GREET (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation) model. Other heating values frequently used by the U.S. Department of Energy can be viewed in table B4 of Oak Ridge National Laboratory's Transportation Energy Data Book (TEDB) and tables A1 and A3 in the Energy Information Administration's (EIA) Annual Energy Review (AER). Some of their similarities and differences are highlighted below:
Heating values listed in the three sources are in general agreement. The only values that differ more than 2% are GREET vs. EIA liquefied petroleum gas (LPG) as well as GREET vs. TEDB liquefied and compressed natural gas.
Both GREET and TEDB average heating values from multiple sources. GREET has 32 sources; TEDB does not list its sources.
EIA cites just one source for each heating value, which can be seen in table A6 of EIA's AER 2006.
Unlike EIA and TEDB, GREET has a complete set of heating values (both lower and higher) for all fuels listed in this reference.
EIA heating values for motor gasoline and LPG weight the average Btu depending on fuel mixture used in a given year, while GREET and TEDB are static.
Specific Notes
[1] Pump octane number is the average of the research octane number and motor octane number.
[2] Energy comparisons are given in percent energy content on a gallon-to-gallon basis unless other units are given. Energy comparisons are calculated using lower (net) heating values from GREET (g). Lower heating values are used because the energy in water vapor is not recovered in transportation engines. However, energy comparisons based on higher heating values may be required for accounting or tax purposes. These can be derived by dividing the higher heating value of a given fuel by the higher heating value of conventional gasoline.
[3] Due to the infinite temperature and pressure combinations of gaseous fuels and their effect on fuel density, ft3 units are not given. Most of these fuels are dispensed by Coriolis flow meters, which track fuel mass and report fuel dispensed on a "gallon of gasoline-equivalent" (GGE) basis.
[4] The ethanol content of E85 is usually lower than 85% for two reasons: 1) fuel ethanol contains 2-5% gasoline as a denaturant and 2) fuel ethanol content is lowered to 70% in the winter in cold climates to facilitate cold starts. When the actual composition of E85 is accounted for, the lower heating value of E85 varies from 82,970 Btu/gal to 89,650 Btu/gal, which is 72% to 77% the heat content of gasoline.
Sources
(a) J. Tuttle and T. von Kuegelgen, Biodiesel Handling and Use Guidelines—Third Edition, National Renewable Energy Laboratory, 2004.
(b) American Petroleum Institute (API), Alcohols and Ethers, Publication No. 4261, 3rd ed. (Washington, DC, June 2001), Table 2.
(c) Petroleum Product Surveys: Motor Gasoline, Summer 1986, Winter 1986/1987. National Institute for Petroleum and Energy Research.
(d) K. Owen and T. Coley. 1995. Automotive Fuels Reference Book: Second Edition. Society of Automotive Engineers, Inc. Warrendale, PA.
(e) J. Heywood. 1988. Internal Combustion Engine Fundamentals. McGraw-Hill Inc. New York.
(f) American Petroleum Institute (API), Alcohols and Ethers, Publication No. 4261, 3rd ed. (Washington, DC, June 2001), Table B-1.
(g) Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) Model, version 1.7. 2007. Input Fuel Specifications. Argonne National Laboratory. Chicago, IL.
(h) The National Biodiesel Board website reports that "most major engine companies have stated formally that the use of blends up to B20 will not void their parts and workmanship warranties." Accessed 8/13/07 at www.biodiesel.org/resources/fuelfactsheets/standards_and_warranties.shtm
(i) J. Sheehan, V. Camobreco, J. Duffield, M. Graboski, and H. Shapouri. 1998. An Overview of Biodiesel and Petroleum Diesel Life Cycles. Report of National Renewable Energy Laboratory (NREL) and US-Department of Energy (DOE). Task No. BF886002.
(j) R.L. McCormick, A. Williams, J. Ireland, M. Brimhall, and R.R. Hayes. 2006. Effects of Biodiesel Blends on Vehicle Emissions. NREL Milestone Report NREL/MP-540-40554.
(k) K. Kelly, L. Eudy, and T. Coburn. 1999. Light-Duty Alternative Fuel Vehicles: Federal Test Procedure Emissions Results. Report of National Renewable Energy Laboratory (NREL), NREL/TP-540-25818.
(l) M. Wang. 2005. Energy and Greenhouse Gas Emissions Impacts of Fuel Ethanol. Presentation to the NGCA Renewable Fuels Forum, August 23, 2005. Argonne National Laboratory. Chicago, IL.
(m) J. Murray, Ben Lane, K. Lillie, and J. McCallum. 2000. An Assessment of the Emissions Performance of Alternative and Conventional Fuels. Report of the Alternative Fuels Group of the Cleaner Vehicles Task Force. Norwich, UK.
(n) Energy Information Administration. Monthly Energy Review. Summary for 2006.