Hydropower: often neglected energy source for post-petroleum era

A nearly inflation-proof energy source? It spunds too good to be true. But it is true. It is hydropower, the renewable energy of falling water. Not only is hydropower the source of one-quarter of the world's current electrical generation but it "promises to be a cornerstone of a sustainable energy economy in the post- petroleum era," writes Daniel Deudney in the latest study from Worldwatch Institute, an environmental research organization.

Although harnessed by such diverse means as slowly turning waterwheels on a tiny stream in Nepal and hundred-ton dynamos at the Aswan Dam on the Nile in Egypt, "hydropower is a neglected energy resource, too often forgotten in the scramble to cope with the energy crunch of the '70s," the report maintains.

A majority of the world's hydropower potential remains untapped. If all the economically available hydropower were harnessed, most of the world's electricity needs could be satisfied, Mr. Deudney argues in the report entitled, "Rivers of Energy: the Hydropower Potential."

"In a world suffering from inflation and fossil-fuel depletion, hydropower offers stable prices and permanence. If properly managed, hydroelectric complexes will be producing power long after the oil wells run dry and the coalfields are exhausted. Economic development based on energy from running water offers something unique among major resources in use today: sustainability ," the report suggests.

An example of this comes from the Pacific Northwest. The large dam projects of the 1930s have given the region the cheapest electricity in the United States. Yet, at the time "critics pronounced us socialists and said we were engaged in a folly to electrify jack rabbit holes," Sen. Henry M. Jackson (D) of Washington recalled recently.

Hydropower is a form of solar energy. Sunlight on the oceans turns water to vapor that is the energy source that drives the weather. Yearly a portion of this vapor condenses into rain over the continents where much of it forms into rivers and streams that are pulled by gravity back to the sea.

In 1980, hydropower produced 23 percent of the world's electricity, or 5 percent of total world consumption. The world's dams have a combined capacity of 363,000 megawatts. A large coal-fired or nuclear power plant produces 1,000 megawatts, by comparison. Yet hydro is realizing only a little of its potential , the Worldwatch analysis says.

All the energy in all the water flowing into Earth's oceans is the equivalent of 73,000 trillion watt-hours a year. Of course, only a portion of this can be practically harnessed. The World Energy Conference estimates that it is technically feasible to capture 19,000 trillion watt-hours yearly from dams with a capacity of 2,214,700 megawatts. Thus, world hydro production could reach four to six times its present level, Deudney argues.

Like any energy source, hydropower has its pluses and its minuses. Still "compared with other sources of electricity -- oil, coal, and nuclear -- hydropower has environmental advantages. While larger dams can cause environmental damage if not carefully planned, hydropower emits no health- threatening pollutants. Nor does it threaten the Earth with catastrophic and irreversible change, as does nuclear waste and the carbon dioxide emitted from coal- and oil-fired generating plants," the study points out.

Large dams, particularly in the tropics, do present serious environmental and social problems, Deudney acknowledges, and he reports that on the drawing boards in China, the Soviet Union, Brazil, and North America are gargantuan projects that make dams like the Aswan in Egypt and the Grand Coulee in Washington state pale in comparison. These projects need even more thorough assessment than has been the case in the past, he urges.

Small-scale hydro projects are far more benign, particularly in the third world, the study points out. The shining example of this is China. Since 1968 the Chinese have built an estimated 90,000 small-scale hydro units that supply some 6,330 megawatts of power, primarily to rural areas.

This approach has not been widely duplicated in other countries, largely because of neglect by international development banks and aid programs. "Since the various benefits associated with small dams -- such as fisheries enhancement and the use of local labor, materials, and initiatives -- are seldom quantifiable, such projects often appear 'uneconomical' in comparison with the large projects whose social costs are hidden" when they actually would be more profitable, the Worldwatch report suggests.

Despite its problems "a concerted effort to develop the Earth's hydropower resources will . . . open the path to a sustainable energy supply, advance the development prospects of the poorer nations, and provide a nonpolluting source of energy desperately needed as the curtain falls on the petroleum era. Perhaps most important, hydropower gives to rather than takes from the future. Every barrel of oil burned is one less for the next generation, but every new hydro plant adds to the energy supply of future generations," the study c oncludes.