Alternative fuel vehicles

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Introduction

Public transit is often called upon as a measure to reduce environmental impacts of travel, both by consolidating travelers from single-occupant vehicles into one environmentally-efficient vehicle, and by using modern technology for cleaner propulsion. The American Public Transportation Association (APTA) estimated that by 2011, about 35% of the transit fleet in America was using alternative fuels or hybrid technologies [1]. Many technologies have been adapted for bus and rail transit, including electricity and battery, natural gas, and hydrogen.

Propulsion Technologies

Standard and Bio-fuels: Gasoline and Diesel

The most common fuels for all vehicles in the U.S. include unleaded gasoline, and diesel. Federal regulations attempting to reduce the impact of these fossil fuels on the environment have mandated supply of ultra-low sulfur diesel and the use of ethanol in gasoline. (SOURCES) Biodiesel fuel blends can typically be used in any modern diesel engine, making an attractive opportunity for agencies to use alternative fuels while avoiding the high cost associated with other technologies such as hybrid-drive buses.

Engine Manufacturers

Practically all bus manufacturing firms offer diesel options, and cutaway buses are commonly available in either gasoline or diesel configurations. The manufacturers producing diesel and biodiesel-compliant engines for buses available in America include:

Natural Gases

Natural gas is used as a fuel in both liquid (LNG) and compressed-gas forms (CNG). (Explain engine differences). Santa Monica, California's Big Blue Bus includes a fleet of buses powered by LNG. Los Angeles County Metropolitan Transportation Authority (LACMTA, or Metro) operates the country's largest fleet of CNG buses.

Bus Manufacturers with Natural Gas Offerings

NABI/New Flyer?

Electric

Electric power for buses is one of the oldest propulsion technologies, adapted from electric streetcars. Buses powered by overhead wires are commonly called "trolley-buses" and still operate today in some cities such as Seattle, San Francisco, Dayton, Boston, and Philadelphia. Buses can also be powered by electric battery without external power such as overhead wires, but the range of these vehicles tends to be limited. The most common application of electric power for buses today is the hybrid-electric.

Hydrogen Fuel Cell

Hydrogen fuel cells has been researched as a power source for buses using Federal funding [2]. AC Transit of California has participated in a hydrogen fuel cell bus testing program since 2000 using Van Hool buses and a power plant developed by UTC Power of Connecticut. In 2013, UTC Power was sold to another company which chose not to continue the fuel cell bus program.

References

  1. APTA. Press release, "More than 35% of U.S. Public Transit Buses Use Alternative Fuels or Hybrid Technology". http://www.apta.com/mediacenter/pressreleases/2013/Pages/130422_Earth-Day.aspx. 22 April 2013
  2. http://www.fta.dot.gov/14617_15670.html