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This report is a follow-up to Bus Futures: New Technologies for Cleaner Cities (2000), which focused on emerging transit technologies. Bus Futures 2006 examines how those technologies have evolved since 2000 and are employed in the transit bus sector.
Transit bus agencies looking to purchase new buses for their fleets are faced with more fuel and technology choices than ever before. They also have to meet a growing number of goals and expectations, such as greater fuel economy, fewer emissions, or better reliability. However, the choices these agencies make affect not only their bottom lines, but the health of the public and the environment.
Bus Futures 2006 is designed to help transit agencies make the best decisions for their service areas and constituents. In addition to explaining the effects of conventional diesel exhaust on humans and the environment, it assesses five types of bus fuels or technologies—clean diesel, natural gas, hybrid-electric motors, biodiesel, and hydrogen fuel cells—for their emissions, noise levels, performance, and costs..
Also, the report describes the technologies employed in each type of bus, discusses their commercial availability, and explains other factors associated with them, such as infrastructure requirements for natural gas buses or engine warranty concerns related to the use of biodiesel. It then identifies several transit agencies that have already incorporated these buses into their fleets.
In researching this report, INFORM analyzed data collected for the American Public Transportation Association’s 2006 Public Transportation Fact Book. These data, gathered from a survey of US transit agencies, show that between 1996 and 2006, alternative fueled or advanced technology buses have steadily increased their share of the transit bus sector, rising from 4.1 percent in 1996 to 18.0 percent in 2006.
Although the majority of these buses are powered by natural gas, the number of hybrid-electric buses placed in service have grown dramatically since 2004, increasing more than five-fold. The number of buses that run on biofuels have also risen during this period, but only slightly.
In recent years, hydrogen fuel cells buses have been developed. The attraction of using hydrogen fuel cells to power vehicles is that water is the only emission generated. (Internal combustion engines powered by fossil fuels such as gasoline, diesel, and natural gas emit many toxic pollutants, including particulate matter, carbon dioxide, and nitrogen oxides.)
Although vehicles that run on hydrogen fuel cells won’t be commercially available for at least a decade or more, INFORM’s research identified six demonstration projects that are testing fuel cell-powered buses on city streets: three in North America, two in Europe, and one in Japan. Despite the promise shown by these pilot projects, numerous technological hurdles must be overcome before these buses will be affordable and practical enough for widespread use.
Until the day when hydrogen fuel cell buses become a viable source of pollution-free public transportation, transit agencies will have to decide which of the several options currently available best meet their needs and their resources. INFORM expects they will use Bus Futures 2006 to help them make these crucial decisions.