Environmental Engineering Reference
emission rate times the total population size. The population growth which
is occurring predominantly in the third world will become an important
For the poor of the world, more energy and more energy services
can mean an improved quality of life. Energy use can allow services that
improve health care, education and nutrition in less-developed nations.
As population or affluence grows, so does pollution. Ultimately the
world population should stabilize and future pollution levels should be
lower for any per capita standard of consumption. A stable population is
a critical part of a sustainable future.
If the buildup of CO 2 and other trace gases is not considered as part of
global development, it is unlikely that greater buildup will be prevented,
except by great advances in alternative fuel systems and programs to
increase energy efficiency.
The world produces about 7.2 billion metric tons of carbon each year
in the form of carbon dioxide. The U.S. produces about 1.7 billion tons.
(See Table 2-5)
Proposed legislation in 1988 called for a 50% reduction in CO 2 in the
United States early in the next century. Our residential and commercial
energy use is about 35% of the total energy used. Industrial energy use is
about 38% and transportation is about 27%.
Almost 40% of our energy is derived from oil. For the electric utilities
about 21% is produced by coal, with about 8% from nuclear, about 23%
from natural gas and the rest from hydro and other renewables. This
accounts for most of the energy use in the United States.
Since coal is the least efficient fuel, it produces the greatest amount
of CO 2 per unit energy. Any increase in the use of coal would substantially
increase CO 2 levels. Moving to more natural gas, nuclear, solar, hydro
or wind power would decrease CO 2 amounts. The Western Governor's
Association in 2004 approved a resolution to increase renewable energy
production, which would require 30,000 megawatts to be produced by
2015 and encourage energy efficiency gains of 20 percent by 2020.
Hydrogen could become a major energy source, reducing U.S.
dependence on imported petroleum while diversifying energy sources and
reducing pollution and greenhouse gas emissions. It could be produced
in large refineries in industrial areas, power parks and fueling stations
in communities, distributed facilities in rural areas with processes using
fossil fuels, biomass, or water as feedstocks and release little or none carbon
dioxide into the atmosphere. Hydrogen could be used in refrigerator-