By Donella Meadows
–August 8, 1991–
“Wind Energy Comes of Age!” proclaims the lead article in the May/June 1991 issue of Solar Today. According to the article there are now over 18,000 commercial wind-powered turbines operating in the U.S. — 80 percent of them in California. The cost of electricity from wind has fallen from 25 cents per kilowatt-hour in 1981 to between 6 and 9 cents today. Costs of wind power are expected to come down another 40 to 60 percent over the next decade.
California’s windmills generate enough electricity to serve the homes of 900,000 people. Their operation last year reduced California’s air pollution emissions by one million tons of carbon dioxide and 7.5 million tons of sulfur and nitrogen oxides. The “capacity factor” — the fraction of time the mills actually produce power — has increased from 13% to 25% as technical failures and repair times have dropped. Capacity is now determined almost entirely by the blowing of the wind.
Breakthroughs in all forms of renewable energy have been coming so fast that if you formed your opinion about them five years ago, it’s time for an update. The costs of solar, wind, and geothermal energy are plunging. These forms of energy are environmentally the best we’ve got — but far from perfect. The advent of renewable energy does not mean the end of environmental problems.
For example, some people consider big windmill farms, like the eighty-square-mile one at Altamont Pass California, a visual blight or at least a waste of land. Wind power proponents point out that 95 percent of the land of a wind farm can still be cropped or grazed. The network of roads to access each mill can cause erosion, though, on the high hills that make good wind sites.
Then there’s the bird problem. Audubon magazine reports that windmill blades at Altamont Pass killed at least 99 birds of prey from 1984 to 1988, a third of which were golden eagles. (Only 50 breeding pairs remain in the area.) The birds go after the populations of ground squirrels that thrive on the wind farm. The managers are trying noise-makers and red and blue paint on the blades to warn the birds away.
If you’ve seen any recent picture of a solar energy plant, it was probably the spectacular Luz International solar thermal plant in the Mohave Desert. This plant covers 1800 acres with shiny reflector troughs, through which run blackened pipes containing oil that is heated by the sun to 735 degrees F. The oil heats water to produce steam to drive turbines. The plant generates 354 megawatts, enough power for 170,000 homes, at 8 cents per kWh.
But the oil is toxic. Water for the steam and for cleaning the mirrors is scarce in the desert. And 1800 acres of desert is lost, part of an ecosystem, by no means a barren one.
Twenty years ago photovoltaic energy — direct conversion of sunlight to electricity without the need for steam and turbine — cost $30 per kWh. It is 30 cents now and is expected to fall to 10 cents by end of this decade. You’d be surprised how much photovoltaic energy is already used in remote sites where the wires don’t reach — by the Coast Guard to power navigational aids at sea, for lights in high ski huts, on remote ranches for pumps and electric fences, and in 15,000 U.S. homes.
But photovoltaic panels tend to be made of materials like gallium arsenide, which is not nice stuff. And periods without sun must be bridged by the use of battery storage, which uses toxic heavy metals. Many people think the ultimate answer to the storage problem will be the manufacture of combustible hydrogen gas from sun-split water. We may even run our cars on solar hydrogen some day. Hydrogen fuel is a technology to watch, but it hasn’t exactly come of age. It’s barely been conceived.
Geothermal energy, tapped from the heat of the inner earth, powers Iceland and 40 percent of El Salvador’s electricity and 11 percent of Kenya’s. In the sites where it’s available, geothermal energy is cheap. It doesn’t have to wait for the wind to blow or the sun to shine. I always thought geothermal generators were benign and long-lasting, but then I began to hear from folks who live near them. Geothermal plants can bring up a lot of mineralized, polluting water out of the ground, and sometimes foul-smelling sulfur fumes as well. And the Geysers plant in California is proving nonrenewable. It’s not running out of earth heat, but of the water that conveys the heat out of the ground and into the turbines.
Biomass energy — such as fuelwood or sugar cane waste for electricity, heat, or gasohol — is cheap and widely used. But biomass is only as environmentally supportable as the agriculture or forestry that produces it.
The potential for renewable energy is enormous. A recent Department of Energy Study found that there are enough favorable U.S. windpower sites to provide at least 25 percent of our current electric demand. (North Dakota and Texas are the “Saudi Arabias” of wind.) The DOE says that all renewables together could supply the equivalent of 50-70 percent of current U.S energy use by the year 2030. And investments in solar technologies provide more than twice as much employment per dollar as investments in oil, gas, or nuclear.
But renewables are not magic bullets. Like all forms of human energy use, they have environmental impacts — lower than the impacts of the energy we use now, but not zero. Renewable energy hasn’t really come of age yet; it’s immature, it’s only an awkward adolescent. But it’s full of promise and growing up fast.
Copyright Sustainability Institute 1991