Dear “Earth Talk”: Aside from wind power, which seems to be gaining in acceptance, what are some other promising sources of nonpolluting renewable energy?
— Bianca Hoffman, Bridgeport, Conn.
Wind power certainly has been in the news lately, with wind farms sprouting up across America from California to the Atlantic seaboard. By the end of 2004, U.S. wind capacity neared 6,800 megawatts, enough to power 1.5 million homes every year. And new projects in the works will add at least 3,000 megawatts of capacity over the next five years, according to the American Wind Energy Association.
Although wind is getting most of the headlines, hydropower — energy generated by water flowing through turbines in dams — is still king of the renewables. Globally, hydropower generates 20 percent of the world’s electricity. In Canada, the world’s largest generator of hydropower, more than 60 percent of the electricity produced comes from the power of water. Norway gets almost 99 percent of its electricity from hydropower, and New Zealand is close behind at 75 percent. In the United States, about 10 percent of all electricity — enough to power 35 million homes every year — comes from hydropower.
Although hydropower does not generate pollution, per se, it has hurt salmon populations on both U.S. coasts and often ruins habitat for wildlife and people. In China and India, large, controversial dam projects have flooded huge areas of land and forced the relocation of whole communities.
One of the world’s oldest fuel sources, biomass — the burning of plant material for energy — is enjoying a renaissance thanks to plentiful supplies of agricultural, forest, and wood waste. Proponents of biomass — or “bioenergy” — say that it could be harnessed as a clean alternative to coal in power plants. Biomass now accounts for 7,000 megawatts of U.S. energy generation, which puts it on equal footing with wind energy.
Solar-powered “photovoltaic” cells, although they now account for only about 1,500 megawatts of power annually in the United States, promise to play a larger role in our energy future. Solar cells keep getting smaller and less costly, are highly reliable, and don’t pollute. And fuel cells, which run on hydrogen and emit water as the only byproduct, hold much promise not just for powering cars (all the major carmakers are developing practical hydrogen-fueled cars) but also for powering buildings and other stationary structures as well.
Despite the promise of renewables, though, the United States still generates more than 90 percent of its energy from nonrenewable and polluting sources such as coal and petroleum — and there is talk of a nuclear revival despite the potential dire consequences of a nuclear accident or terrorist act. Finding more efficient ways to harness solar energy is a top priority for many environmentalists; the Earth receives more energy from the sun in just one hour than the world uses in a whole year.
For more information: American Wind Energy Association, www.awea.org; National Hydropower Association, www.hydro.org; American Bioenergy Association, www.biomass.org; U.S. Department of Energy Renewable Fuels Program, www.eia.doe.gov/fuelrenewable.html.
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