Energy and Changes in the Environment - Hydrogen and Fuel Cells: Advances in Transportation and Power - page 57

and software design will continue to improve our gross national product
while reducing our dependence on oil and coal.
Many studies assume improvements in the gas mileage of cars
and efficiency in the production of energy in power plants, in industrial
applications and in home heating, lighting and other sectors. U.S.
manufacturers could improve the average energy efficiency of cars and
trucks. But, as America's fleet of older vehicles is replaced with newer cars
with less pollution, CO 2 emissions may change very little or even increase
since additional miles may be driven.
One high-efficiency case assumes that by the year 2010 new cars
would average 52 miles per gallon and would penetrate 50% of the U.S.
market. This would be possible if small hybrids take over a major part of
the market.
Other studies predict that new car efficiencies could be even greater
than that, with a fuel economy for the average vehicle of 75 miles per gallon.
One NEPP report assumes that the U.S. economy would reduce its
dependence on energy at the rate of about 1.7% per year, while others
believe that more active efforts to make our economy less dependent
on energy could result in a rate of about 4% per year. They also assume
very high-efficiency lighting and the rapid deployment of electric-power-
generating stations that are 50% or more efficient than present facilities.
Improvements in efficiency along with major efforts to redirect
energy use towards improved environmental quality would not only
reduce emissions but there would be many other benefits.
In 1950 the U.S. CO 2 emissions were almost 40% of the global total.
By 1975 this had dropped to about 25%, and by the late 1980s it was about
22%. If the U.S. held emissions constant at 1985 levels, a reduction of
15% from the emissions in 1995 and a 28% reduction from the forecast
emissions in 2010, then global emissions would be reduced by only 3%
in 1995 and 6% in 2010. Even if U.S. emissions were cut by 50% below the
1985 levels, global emissions would continue to grow and would drop by
less than 15% in the year 2010. This supports the assumption that world
emissions will continue to grow.
Indirect effects are also very likely, because if the U.S. employed
technology to reduce CO 2 emissions, then the resulting cost reductions
would provide a competitive advantage for a while and would then be
imitated by foreign competitors. This could energize global emission
reductions. One path would be to develop crop strains that could take
advantage of CO 2 .