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Acknowledgments US Department of Transportation - BTS

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Jet fuel is the only other petroleum-based fuel that is used in large quantities (over 1 million barrels/day) in thetransportation sector. Virtually all <strong>of</strong> it is used by airlines. These data are accurate because airlines are required toreport usage, and because there are relatively few certificated air carriers, data collection should be manageable.NONPETROLEUM FUELS CONSUMPTIONTABLE 4-10. Estimated Consumption <strong>of</strong> Alternative and Replacement Fuels for Highway VehiclesCollectively, oxygenates, natural gas, electricity, and various alternative fuels amount to only about 3 percent <strong>of</strong> allenergy used in the transportation sector. While this may not be much greater than the error bars associated withpetroleum use, it is important to track changes in these fuels accurately.OxygenatesOxygenates, mostly methyl tributyl ether (MTBE), which is derived from natural gas and ethanol, are part <strong>of</strong>mainstream gasoline supply. They are measured routinely with petroleum supply (forms EIA-819A and 819M).Consumption is estimated from production, net imports, and stock changes. Refineries and other entities are requiredto report data on oxygenates, and EIA also monitors production capability to provide a crosscheck. Thus, oxygenatesdata are likely to be reasonably accurate.Natural GasNatural gas is used in the transportation sector mainly as the fuel for compressor stations on natural gas transmissionlines. A small but growing amount is used in compressed or liquefied form in vehicles. EIA collects data on naturalgas much as it does for petroleum, but the system is much simpler. Natural gas transmission companies may notknow exactly how much gas is used in compressor stations, but they have a good idea based on the size <strong>of</strong> theequipment and the load on the line. The reported numbers probably are reasonably accurate. Data on natural gasfueledvehicles are collected by DOE via Form-886, which is sent to fuel suppliers, vehicle manufacturers, andconsumers. In addition, private associations and newsletters are important sources <strong>of</strong> information on alternativevehicles and alternative fuels use. Since most groups work cooperatively with DOE, it is likely that the data reportedare accurate. EIA tracks the number <strong>of</strong> natural gas vehicles and the number <strong>of</strong> refueling stations to provide a crosscheck on estimates <strong>of</strong> natural gas consumption.ElectricityElectricity powers intercity trains (Amtrak) and intracity rail systems. In addition, the number <strong>of</strong> electric vehicles isgrowing. There is considerable uncertainty over the energy consumed by these modes. Amtrak no longer providesnational totals <strong>of</strong> its electricity consumption. Data on intracity transit is based on U.S. <strong>Department</strong> <strong>of</strong> <strong>Transportation</strong>,Federal Transit Administration's (FTA's) National Transit Database (NTD). The legislative requirement for the NTD isfound in Title 49 U.S.C. 5335(a). Transit agencies receiving funds through the Urbanized Area Formula Program aregenerally required to report financial and operating data, including energy use. Although the data is generallyconsidered accurate because FTA reviews and validates information submitted, reliability may vary because sometransit agencies cannot obtain accurate information or may misinterpret certain data.If electric vehicles become important over the next decade or two, dedicated charging stations may becomecommonplace, which could provide accurate data. Fleet owners (e.g., electric utilities) can keep accurate records, butindividuals who plug their vehicles in at home may not. Electricity use must be estimated from the number <strong>of</strong> suchvehicles and the expected driving cycles. Hence, data on electric power for transportation must be viewed as anestimate.It should also be noted that electricity is a form <strong>of</strong> work that usually is generated from heat with the loss <strong>of</strong> about twothirds<strong>of</strong> the energy. Automobile engines are equivalent to electric generators in that they convert chemical energy toheat and then to work, losing most <strong>of</strong> the energy as waste heat. When electrical energy is compared to petroleum intransportation, the waste heat must be included for consistency. A kilowatt-hour <strong>of</strong> electricity is equivalent to 3,413British thermal units (Btu), but about 10,000 Btu <strong>of</strong> heat are required to produce it. This factor is dropping asgenerators become more efficient. High efficiency gas turbines may require 8,000 Btu or less, but the average ismuch higher. It is usually impossible to tell where the power for a specific use is generated, so average figures for aregion are used to estimate the waste energy, a factor that further reduces the accuracy <strong>of</strong> the data.

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