Tilting with Windmills

Oil prices may skyrocket and energy crises come and go, but the winds will blow forever. In an effort to tap that inexhaustible source of energy, everyone, from NASA's skilled aerodynamicists to do-it-yourself basement tinkerers, is now suddenly rediscovering one of the oldest technologies known to civilized man: the use of the windmill.

Near Sandusky, Ohio, NASA'S Lewis Research Center is putting finishing touches on a lOO-ft.-tall experimental steel windmill with two 62-ft.-long aluminum blades. When these blades begin turning in the summer breezes off Lake Erie later this month, they should produce as much as 100 kilowatts of electricity, enough to meet the needs of 30 one-family homes. Other projects range from a large eggbeater-shaped rotor being tested by New Mexico's Sandia Laboratories to small sail-driven devices created by such ecology-minded outfits as R. Buckminster Fuller's Windworks in Wisconsin and the food-growing New Alchemy Institute on Cape Cod (TIME, March 17). Long Island's Energetics Nine, Inc., recently started selling wind-driven units that deliver from 750 to 12,500 watts of electricity (an average refrigerator requires 250 watts). Some scientists estimate that with enough federal support for research and development (up to $18 million may be available this fiscal year), windmills could fill 20% of U.S. electrical needs--and perhaps even more--by the year 2000.

Small windmills were once common sights in rural America. In the 1920s and '30s, thousands of them supplied electricity for Midwest farms. Then the cheap power brought by the New Deal's rural electrification program finally made most of the durable fixtures obsolete. During World War II, a giant 110-ft, 1,250-kilowatt wind-driven generator built on a hill called Grandpa's Knob outside Rutland, Vt., created a flurry of renewed interest in wind power --until one of the monster machine's eight-ton blades, weakened by metal fatigue, tore off and hurtled 750 ft. into the air before crash-landing.

Advances in metallurgy and aerodynamics make such disasters much less likely today. NASA's Ohio windmill, for instance, borrows directly from helicopter design. Like a chopper's rotor, the 2,000-lb. blades can be "feathered" (or turned on their axes), by manual control; they will continue to whirl at a steady 40 r.p.m. even as the wind varies. In future NASA models, chip-sized computers developed for spacecraft will monitor the performance of the windmills and automatically command them to adjust to wind changes.

Excess Power. Unlike NASA'S traditional configuration, Sandia's upright eggbeater does not have to turn to face the breeze; its symmetrical shape offers the same surface to winds from any direction. Cribbing from jet aircraft, Polytechnic Institute of New York engineers are experimenting with a delta-shaped airfoil used in conjunction with standard windmill rotors. Pointing into the wind, the triangular whig amplifies the wind's power at least fivefold; the wind is focused into whirling streams that strike the rotors. Other teams at General Electric and at Connecticut's Kaman Corp., a helicopter manufacturer, are considering blades up to 100 ft. long. If these behemoths can be made strong enough to rotate without tearing apart, they could generate up to 3 megawatts (3 million watts) of electricity.

However they improve their wind-driven generators, designers face a new problem. Whenever the wind died down, farmers in the 1930s drew electric current from old-fashioned storage batteries charged by their windmills. The bigger windmills of the future will require far greater storage capacity. One possibility: excess power produced on windy days could be used to pump water uphill into storage reservoirs; when the wind stops, the water could be allowed to cascade down through hydraulic turbines. Similarly, the energy from flywheels, spun up to a high speed when windmills are working, could be used to run electrical generators when the wind ebbs. University of Massachusetts Engineer William Heronemus has an even more imaginative scheme: he would use the windmill's electrical output to break down water molecules into their component atoms of hydrogen and oxygen. The highly combustible hydrogen gas could then be used as a fuel to power stand-by generators.

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