Energy and Changes in the Environment - Hydrogen and Fuel Cells: Advances in Transportation and Power - page 65

design of combustion chambers and the computer control of combustion
mixtures. Exhaust-gas catalytic converters also limit emissions. But,
electric and fuel cell-powered cars could greatly reduce air pollution in
cities, but only if the electric power sources used to charge the batteries
or create the hydrogen fuel were themselves less polluting. More energy-
efficient mass transit can also reduce emissions.
Seattle, Portland, San Diego, Salt Lake City, Austin and Minneapolis
are among the cities that have implemented programs to cut carbon dioxide
emissions along with Boulder and Fort Collins, Colorado, Burlington,
Vermont, Cambridge, Massachusetts, and New Haven, Connecticut.
Chicago and Los Angeles have adopted climate protection programs. San
Francisco plans to reduce its greenhouse gas emissions by more than 2.5
million tons with mass transit and hybrid vehicles, energy conservation,
green building codes and solar power for buildings and homes. Seattle's
municipally owned electric utility has adopted a climate-neutral program
where it invests in emissions reductions programs around the world
to offset its own carbon dioxide output. In 2008 California changed its
decision to force automakers to cut carbon dioxide emissions from cars
and trucks by relaxing its zero emissions program.
In the 1980s, U.S. carmakers fought against tighter fuel economy
standards. When the energy crisis began in 1973, American automobiles
averaged about 13 miles per gallon of gasoline (mpg). By 2003, that number
had increased to 22 mpg.
The number of vehicle miles traveled has more than doubled
between 1970 and 2003 to almost 2.9 trillion miles, so these gains in fuel
efficiency were mostly offset. The improvement in efficiency was spurred
by legislation passed in 1975 that established Corporate Average Fuel
Economy or CAFE rules. This allowed automakers to produce any kind of
car as long as all the vehicles when averaged meet the mpg standards set
by the government. In 1992, when Bill Clinton campaigned for president
he promised that he would increase the CAFE standard to 45 MPG.
About this same time period, President Bush signed a global warming
treaty at the 1992 Earth Summit in Rio de Janeiro, Brazil. In this treaty,
industrialized nations agreed by the year 2000 to voluntarily cut back their
carbon dioxide emissions to the level they were at in 1990. To meet this
goal, U.S. vehicles would need to be three to four times more efficient than
they were, averaging about 80 to 90 MPG.
The auto industry balked at Clinton's 45 MPG goal and when elected,
Clinton broke his promise. In 1993, the administration announced that the