Mass Transit:

Use of Alternative Fuels in Transit Buses

RCED-00-18: Published: Dec 14, 1999. Publicly Released: Dec 14, 1999.

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John H. Anderson, Jr
(202) 512-8024


Office of Public Affairs
(202) 512-4800

Pursuant to a legislative requirement, GAO reported on the: (1) status of the development and use of alternative fuel technologies in transit buses, particularly the use of compressed natural gas (CNG) as a fuel; (2) air quality benefits of such technologies; (3) costs incurred by transit operators to use CNG buses, as well as other alternative fuels, compared with the costs to use diesel buses; and (4) primary incentives and disincentives for using these technologies.

GAO noted that: (1) alternative fuel buses account for a very small, but growing, portion of the nation's transit bus fleet; (2) in 1997, 5 percent of the nation's approximately 50,000 transit buses operated on some alternative fuel system; (3) the most commonly used alternative to diesel fuel is CNG--accounting for an estimated 75 percent of the full-sized alternative fuel transit buses in 1998; (4) transit operators are also beginning to test and demonstrate new propulsion system technologies in their transit buses; (5) hybrid electric transit buses are available, and fuel cell buses will be commercially available by 2002; (6) data are limited on the extent to which alternative fuel transit buses provide air quality benefits in urban areas; (7) on a national scale, transit buses do not significantly affect air pollution levels because, according to the Department of Transportation, they constitute only about 0.02 percent of the approximately 208 million automobiles, trucks, and other vehicles in the United States; (8) however, because individual alternative fuel transit buses emit less pollution than do individual diesel buses, alternative fuel buses have some beneficial effect on the air quality of the urban areas in which they operate; (9) transit operators pay more to buy, maintain, and operate CNG buses than they pay for diesel buses; (10) operators that buy CNG buses typically pay approximately 15 to 25 percent more for each of these buses than they do for diesel buses; (11) the costs of installing fueling facilities and upgrading maintenance garages for CNG buses vary among transit operators; (12) however, constructing a compressed natural gas fueling station typically costs about $1.7 million, and modifying a maintenance facility typically costs about $600,000; (13) six of the eight transit providers GAO spoke with were able to provide operating cost estimates reporting higher operating costs, higher maintenance costs and higher fuel costs for their CNG buses than for their diesel buses; (14) transit operators approach the decision, of whether switch to alternative fuels by considering a range of factors, such as adhering to more stringent emission standards and the public's concerns about transit bus pollution; (15) factors such as the increased costs and reduced reliability of alternative fuel buses experienced to date discourage the use of fuels other than diesel; and (16) diesel buses have become significantly cleaner over the past 11 years, thereby reducing the environmental advantages of shifting to alternative fuel buses.

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