Iowa to harness wind at compressed air power plant
Author: Leonard Anderson
A group of Iowa municipal electric and gas utilities plans to build a $200 million generating station based on a technology called compressed air energy storage, or CAES, near Fort Dodge, Iowa.
Project advisor Tom Wind said the target for starting work on the plant site is the second half of 2004 with completion in 2006.
The Iowa Stored Energy Plant would store compressed air in an underground aquifer to be released and blended with natural gas to fire combustion turbines to make electricity for transmission over the state's power grid.
Compressed air would replace about two-thirds of the gas normally burned in a turbine.
Backers said the stored energy could generate up to 200 megawatts of electricity, or power for about 200,000 homes.
Energy from a new 100 megawatt wind power farm would be tapped to run compressor motors to force air into the aquifer at a pressure of 500 pounds per square inch.
Wind turbines also could generate electricity for direct transmission over the grid, with 1 megawatt powering about 300 homes.
There is only one other compressed air energy storage plant in operation in the United States, the Alabama Electric Cooperative Inc.'s 12-year-old McIntosh power station in McIntosh, Alabama.
There is also a 25-year-old CAES station in Huntdorf, Germany.
"The main benefit of CAES is that energy in the form of compressed air can be stored to generate power when it is needed or most valuable," said Wind, a power engineer and advisor to the Iowa Association of Municipal Utilities.
The downside depends on the price and availability of natural gas supplies, he added.
Texas is another possible site for a wind-powered stored energy system, and there has been talk of one in Ohio.
Iowa, however, is drawing a lot of attention for wind power development with Gov. Tom Vilsack pushing to add 1,000 megawatts of renewable energy a year to the state grid by 2010.
Des Moines, Iowa-based Mid-American Energy, a power company controlled by Buffett, plans to build the world's largest wind farm in northern Iowa - a $323 million, 310 megawatt project.
While wind power is growing in the United States, it accounts for only a couple of percentage points of total electricity supplies.
Last year, total U.S. wind power grew 10 percent to nearly 4,700 megawatts, or enough to power about 1.4 million homes, but growth trailed a global growth rate of 28 percent, according to the American Wind Energy Association.
Industry officials say domestic wind energy could expand rapidly if the federal government approved a smoother tax credit for wind power than the one first enacted in 1994.
The slow economy has stunted wind growth but a rocky credit transition also hurt. A federal tax credit expired in late 2001 and a new credit was not signed into law until March 2002.
The tax credit is set to expire on Dec. 31, but a three-year extension is included in both the Senate and House versions of the energy bill now being considered.
The Iowa project has a ways to go before any electricity flows. About $680,000 has been raised from municipal utilities and a business plan has to be developed, said Patti Cale-Finnegan, energy services coordinator for the group.
Project financing could be arranged through the Iowa Public Power Agency, which aims to help municipal utilities develop renewable energy, she said.