Wind Power Is Getting Too Good To Resist

Electrical power generated by wind turbines accounts for a tiny fraction of the U.S.'s total usage, but the potential is enormous. In fact, the Pacific Northwest Laboratory says the wind blowing over some parts of the western and midwestern states could generate more power than the known oil reserves of Saudi Arabia. The country's estimated reserves at 261 billion barrels is enough for about 90 years at the current production of 8 million barrels/day. If burned to produce electricity, that oil would generate about 153 trillion kW-hr. The Lab estimates U.S. wind resources in the West and Midwest as capable of producing 10.8 trillion kW-hr annually. Thus, in 15 years, U.S. winds could generate more electricity than all of Saudi Arabia's oil, and without being depleted. So why isn't wind power more widely used?

Modern wind turbines won't be a main power source for a developed country any time soon, but with the capability of generating electricity at about 6 cents/kWh without pollution, it's getting too good to ignore.

One concern has been the intermittent nature of wind power. Although it cannot supply on demand, it's predictable and can contribute to an "energy mix." That means when it is producing energy, other sources can be scaled back. Cost has been another inhibitor. But today, say experts, wind power is cost competitive in many areas with natural gas at about 3 to 6 cents/kW-hr to produce.

Costs have declined thanks to the economies of scale associated with the larger wind turbines now being manufactured and to technological advancements. These include variable-speed and constant-frequency technology, dynamic voltage controls and advanced wind-turbine blades.

The trends
Manufacturers in the windpower industry cater to two types of clients, small and large. Small machines are usually rated below 100-kW capacity and are intended for use by villages, remote operations, and commercial establishments such as small factories. Larger units, 750 kW and up, are for electrical utilities and independent power produces who will install them at windy locations.

As the industry has grown, so have the turbines. "Greater generating capacity from a single turbine is certainly one trend," says James Johnson, an engineer with the National Renewable Energy Laboratory, Boulder, Colo.

The map shows wind speeds for sites in the U.S. Areas with winds of 6 m/sec or greater have commercial possibilities.

A few years ago most wind turbines were of the 750-kW variety, but today, more megawatt-sized machines are being ordered. At least one 3.2-MW turbine is slated for installation in Europe. And Enron Wind, a wind-turbine manufacturer in Tehachapi, Calif., has a 3.6-MW unit in development. Engineering changes have been just about everywhere. Research at NREL has tuned the air foils in the blades so they now capture more energy than those from just a few years ago. "The designs also reduce operational maintenance by compensating for leading-edge roughness," says Johnson. "A lot of insects in warm climates hit the leading edge of the airfoil, decreasing its efficiency. But newer designs compensate for that roughness and don't have to be cleaned as often."