Batteries for wind farms

Sydney Morning Herald
Thursday 29/7/2010 Page: 6

THE rapid growth of wind farms, whose output is hard to schedule reliably or even predict, has electricity providers in the US 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 struggling to maintain stability as supplies fluctuate.

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

On Maui, for example, wind generating capacity overall 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% goal. For now, the best option seems to be storage batteries.

In New York and California, companies are exploring electrical storage that is big enough to allow for "arbitrage", or buying power at a low price, such as in the middle of the night, and selling it hours later at a higher price. Renewable goals can be met, many in the industry insist. But if the energy source is intermittent, "you can't do that without batteries of some sort", said Peter Rosegg, a spokesman for the Hawaiian Electric Company. His company has agreed to buy electricity from a wind farm on the northern shore of Oahu, where the power company First Wind, of Boston, has just broken ground.

The spot is one of Hawaii's best wind sites. Mr Rosegg said, but the supply is gusty and erratic. What is more, it is at the farthest point on the island from the company's main load centre. Honolulu, and does not even lie on its high-voltage transmission backbone. So the 30-MW wind farm, which will have enough power to run about 30 Super Walmarts, will have Xtreme Power of Austin. Texas, install a 15-MW battery. Neither First Wind nor Xtreme Power would say what the project cost, but publicly disclosed figures put the project about $US130 million ($145 million), with about $US10 million for the battery. The Energy Department has provided a $US117 million loan guarantee.