Environmental Engineering Reference
environmental reasons and also because of the dislocation of population that is often involved in
creating upstream reservoirs.
Geothermal energy supplies a significant portion of electricity in the following countries: El
Salvador (28.5%), Nicaragua (18.5%), Costa Rica (10.3%), New Zealand (5.7%), Iceland (5.3%),
Mexico (3.8%), Brazil (2.6%), Indonesia (1.8%), and Italy (1.6%). Geothermal energy has a
great potential for supplying heat and electricity to many areas of the world. However, at present,
geothermal energy is only competitive with fossil energy where the geothermal sources are on, or
near, the surface of the earth.
In contrast to fossil-fueled power plants, nuclear power plants do not emit any CO 2 into
the atmosphere, nor do they emit the other fossil-energy-related pollutants (SO 2 ,NO x , particulate
matter). However, the fear of nuclear accidents and the unresolved problem of nuclear waste disposal
has brought the construction of additional nuclear power plants to a halt in many countries. In the
United States, several nuclear power plants are presently being decommissioned even before their
normal retirement date. On the other hand, in some countries, new nuclear power plants are being
constructed, and nuclear energy does provide a significant portion of the total electricity production.
For example, in France 76% of the electricity is nuclear-electric, South Korea 36%, Germany 29%,
Taiwan 27%, and Japan 26%.
GLOBAL CARBON EMISSIONS
Table 2.2 lists the total carbon emissions, carbon emissions per capita and per GDP of several
countries in the world in 1996. (Emissions are reckoned in mass of carbon, not that of CO 2 .) In
terms of absolute quantities, the United States and China are the largest emitters of carbon [1407 and
871 million metric tons per year (Mt/y), respectively], followed by Russia (496 Mt/y). In terms of per
capita emissions, the United States and Canada were the largest emitters, 5270 and 4040 kilogram
per capita per year, followed by Russia, 3340 kg/cap y. In countries where nonfossil energy is used
for electricity generation and other purposes, the per capita carbon emissions are lower. Thus, while
the energy consumption per capita in Germany and France are similar (168 and 162 MBtu/cap y,
respectively), the carbon emissions are quite different (2790 and 1600 kg/cap y, respectively). This
reflects the greater use of nuclear energy for electricity generation in France. Similarly, Switzerland
and New Zealand have lower carbon emissions per capita (1470 and 2100 kg/cap y, respectively)
than other industrial countries, because of their use of hydroenergy and geothermal energy. The
world average is 1100 kg/cap y. The United States emits about five times as much carbon per capita
as the world's average.
In terms of carbon emissions per dollar GDP, an interesting picture emerges. The ratio in the
United States and Canada is 0.26 and 0.25 kg carbon per dollar GDP (reckoned in 1987 U.S.
dollars), respectively, whereas in Japan, Germany, France, Italy, and the United Kingdom, it ranges
from 0.1 to 0.2 kg/$. In part this stems from the higher consumption of energy per unit of GDP in the
United States and Canada, but also from the fact that the United States and Canada use more fossil
fuel per capita for space heating, space cooling, and transportation than do the European countries
and Japan. In Russia, the ratio of carbon emission per dollar GDP is 2.01, China 1.62, India 0.65,
Indonesia 0.62, and Mexico 0.63 kg/$. In these countries, fossil fuel is not used as efficiently in
the production of GDP. The exception is Brazil, where the ratio is 0.2 kg/$, probably on account of
Brazil's greater use of hydroenergy and biomass energy. (Note that emissions from forest burning
are not included in these estimates.)