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Tuesday, August 03, 2010

Environment - "Wind Drives Growing Use of Batteries"

Here is a really interesting NY Times article from July 27, 2010, reported by Matthew L. Wald. Some quotes:

The rapid growth of wind farms, whose output is hard to schedule reliably or even predict, has the nation’s electricity providers scrambling to develop energy storage to ensure stability and improve profits.

As the wind installations multiply, companies have found themselves dumping energy late at night, adjusting the blades so they do not catch the wind, because there is no demand for the power. And grid operators, accustomed to meeting demand by adjusting supplies, are now struggling to maintain stability as supplies fluctuate.

On the cutting edge of a potential solution is Hawaii, where state officials want 70 percent of energy needs to be met by renewable sources like the wind, sun or biomass by 2030. A major problem is that it is impossible for generators on the islands to export surpluses to neighboring companies or to import power when the wind towers are becalmed.

On Maui, for example, wind generating capacity over all will soon be equal to one-fourth of the island’s peak demand. But peak wind and peak demand times do not coincide, raising questions about how Hawaii can reach its 70 percent goal. For now, the best option seems to be storage batteries.

Here are some other strategies:
At a pumped hydro plant, off-peak electricity is used to pump water from a reservoir at a low elevation to one at a higher one. At hours of peak demand the water flows back down through a turbine, creating electricity.

Electric companies are using other strategies for storage and frequency regulation. In Stephentown, N.Y., near Albany, a Massachusetts company, Beacon Power, is building a bank of 200 one-ton flywheels that will store energy from the grid on a moment-to-moment basis to keep the alternating current system at a strict 60 cycles.

Atop each flywheel is a device that can be a motor at one moment and a generator the next, either taking energy and storing it in the flywheel or vice versa. The Energy Department provided a $43 million loan guarantee to assist in the $69 million project.

The Energy Department is also supporting storage projects that rely on compressed air. Surplus electricity is used to pump air into an underground cavity; when the electricity is needed, the air is injected into a gas turbine generator. In effect, it acts as a turbocharger that runs on wind energy captured the previous night, instead of natural gas burned at a peak hour.

Here is a collection of some other NYTimes wind turbine stories.

Posted by Marcia Oddi on August 3, 2010 09:08 AM
Posted to Environment