New York Times - 26 Aug 08

Prof. Robert B. Laughlin
Department of Physics
Stanford University, Stanford, CA 94305
(Copied 3 Jan 10)

Air Storage Is Explored for Energy

Published: August 26, 2008

When Mayor Michael R. Bloomberg dreamed out loud last week about a New York skyline filled with wind turbines, one of the most serious issues raised by the naysayers was that the wind does not always blow when you need it.

But a New Jersey company plans to announce on Tuesday that it is working on a solution to this perennial problem with wind power: using wind turbines to produce compressed air that can be stored underground or in tanks and released later to power generators during peak hours.

The company, Public Service Enterprise Group Global LLC, a subsidiary of P.S.E.G. Energy Holdings, is forming a joint venture with Michael Nakhamkin, a leader in the development of energy storage technology. The new company, Energy Storage and Power, will promote the use of compressed air storage technology to utilities and other power producers. (P.S.E.G. Global is the sister company of Public Service Electric and Gas Company, New Jersey's largest power distributor, which has 2.2 million customers.)

The technology has been around for decades, though the only major plant in the United States opened in Alabama in 1991. Another plant was built in Germany in the 1970s. But compressed air storage is getting a fresh look because so many windmills have been built across the country in recent years, and energy producers are increasingly looking for ways to avoid building power plants that rely on expensive oil and natural gas.

Dr. Nakhamkin, who worked on the plant in Alabama, has developed new technology that reduces the startup time for generators powered by compressed air and cuts the amount of emissions they produce. The new facilities would also use more standard components, which would make the plants cheaper to build, depending on how much mining is required to create an underground reservoir.

"This is a game-changing technology," said Stephen C. Byrd, the president of P.S.E.G. Energy Holdings, which will invest $20 million over three years. "There is a desire for energy independence, and this will reduce the need for oil and natural gas."

The venture has met with utilities that might buy the storage technology. Compressed air can be produced by a variety of fuels. But the new venture hopes to put wind power generated during off-peak hours to use during peak hours - typically 9 a.m. to 5 p.m. - and especially on hot days.

One of the main challenges to using wind power is that the wind, in general, is unpredictable, which makes it harder for utilities to rely exclusively on it since they prefer to buy energy a day or more in advance.

In New York, that unpredictability is compounded by the fact that the city is at its windiest on winter nights, while power use peaks on sticky - and still - summer days.

P.S.E.G. Global is trying to win a contract to build 95 windmills that would produce a maximum of 350 megawatts of electricity off the New Jersey coast. If the company is chosen, it would consider linking the windmills to a compressed air storage plant, Mr. Byrd said, and then feeding it into the power grid.

If a storage plant were to be built in New Jersey, it would most likely use above-ground tanks or abandoned gas pipelines because so much of the state is on solid rock, which would be expensive to excavate, Mr. Byrd said.

More favorable locations, he said, include upstate New York, where there are depleted salt mines as well as wind farms. Old coal mines and tapped-out natural gas fields can also be converted into underground reservoirs.

Roy Daniel, the chief executive of Energy Storage and Power, said that an underground reservoir the size of Giants Stadium could hold enough compressed air to power three 300-megawatt plants. (One megawatt hour can power a large hospital for an hour.) The reservoirs, which are typically more than 1,500 feet below ground, could take eight hours to fill at night. The compressed air would be released to run generators for eight hours during the day.

Though the former Fresh Kills landfill on Staten Island has been deemed suitable for a wind farm, and the mayor has envisioned a future in which the city's bridges and skyscrapers are topped with turbines, a compressed air storage plant is unlikely to be built in New York City because of the rocky underground and the lack of free space above ground.

But New York utilities could buy power stored and produced anywhere. Advocates of wind power support the use of compressed air storage facilities, but say that almost all of the wind power produced nationally is fed straight into the grid without having to be stored.

"Different sectors like to associate with wind power, and if compressed air will truly help wind, then fine," said Robert E. Gramlich, the policy director at the American Wind Energy Association. "But we don't want to give anyone the impression that storage is needed to integrate wind. Even growing 20-fold, storage isn't needed."

Mr. Gramlich pointed to a federal Department of Energy report that showed wind power could meet 20 percent of electricity needs in the United States by 2030 without the need for storage facilities.

Still, storage facilities could help reduce the need to build new gas and coal plants, or to use current plants, powered by fossil fuels.

"In the next couple of years, we want to install a couple of them so it becomes a tool in the toolbox to meet needs," said Arshad Mansoor, the vice president of power delivery and utilization at the Electric Power Research Institute.