Keeping the Wind Steady

Power from wind is a growing energy resource in these days of expensive petroleum. The question that lingers over the nature of wind is its intermittency. We are at the mercy of the weather when it comes to harnessing the force of rushing air. This does not play nice oftentimes with the power grid. In "Taking Wind Mainstream", author Karl Stahlkopf explains that new technology is available to help solve the problem.

No one questions winds enormous potential. In the United States, just 0.6 percent of the land would have to be developed with wind farms to provide 15 percent of the nation's electricity, according to Stahlkopf. Plus, wind is both price-competitive and price-stable. Still, turbines only turn when the wind is blowing. How do we store energy from wind's peaks of production to balance it against its lulls? Two words: power electronics. Using large semiconductor devices, we can enable wind farms to provide rapid response to fluctuations in grid frequency and voltage.

Stahlkopf is the senior vice president and chief technology officer at Hawaiian Electric Co. (HECO), which has been in the wind power business for years. He writes that power electronics can be integrated with new storage technologies to keep shifts in wind power production manageable. (And developing larger supergrids across continents will also help to distribute wind power across whole regions, balancing areas where the wind happens to be blowing with those that may be becalmed, while simultaneously spreading the burden of providing backup power.)

HECO has a proof-of-concept program it has developed to put together power electronics and storage technologies. They call their system the Electronic Shock Absorber (ESA), which has been operating since January on the Big Island. According to Stahlkopf, the ESA absorbs power briefly when it detects a sharp increase in the instantaneous output of the wind farm by a strong gust and injects power when the bluster dies down. The ESA system also can regulate reactive power (the product of current on a transmission line that is alternating out of phase with its voltage).

Stahlkopf argues that this is a problem that can be solved with intelligent R&D and upgrading of transmission technology. Most importantly, it has a payoff that will be enormously valuable to the challenges of producing clean, renewable energy at an affordable rate, as well as ensuring the reliability and security of the power vitally needed to run our economies.

It's a powerful argument. Give it a read. This may be one case where the answer really is blowing in the wind.


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