Site for ISEP Development is Officially Announced

ISEPA is closely analyzing a location just west of Dallas Center in central Iowa. The site lies within 30 miles of downtown Des Moines, and is the third location ISEPA researched after initially screening more than 20 geological structures in Iowa. ISEP will employ CAES, which utilizes air stored underground at naturally occurring pressures. Stored air is released when needed to help generate energy for cities and utilities which have purchased rights to utilize it. Used as a supplement to existing energy sources, it is predicted that it will save clients millions of dollars each year by providing a consistently reliable energy source, much of it renewable, that would be available during periods of high demand.

"It’s a good location," said McGill. "The reservoir is deep enough and wide enough, with good geology." The condition of the reservoir rock was crucial to the development, as ISEP will differ from the reservoir geology – caverns in underground salt – used by the other two operating CAES facilities in Alabama and Germany. Storage in salt and utilization of pre-existing underground mines developed during minerals production are typical avenues pursued for CAES storage facilities. But ISEP will be the first facility of its kind to use a porous sandstone layer far under the earth’s surface to hold the compressed air. The air will be pumped into the sandstone, will displace water that exists there in a limited and carefully controlled area, and will form a "bubble," which will remain in place as an underground reservoir of stored energy. It will be tapped by wells, which will allow air out when needed to provide electricity.

ISEP will combine the underground storage of air with energy derived from wind power in Iowa, making the project doubly attractive as Iowa strives to further the advancement of wind energy. Some of the energy collected by wind turbines will drive compressors to push the air underground. ISEP will provide 268 megawatts of CAES generating power and plans to use approximately 75 megawatts of wind power. "ISEP offers the best means to assure full utilization of wind energy, whether that power is created by ISEP or purchased," said McGill. He stated that it will ensure that wind energy will be available to ISEP customers when most needed (instead of relying on the uncertain availability of wind), and will help cities and utilities avoid much of the "carbon tax" which is likely to be imposed on fossil fuel burning facilities in the future.

Cities and utilities participating in ISEP will utilize a mix of energy sources, of which energy from ISEP will be one component. It is anticipated that most ISEP customers will continue to use technology such as coal-fired steam generating power plants to serve their "baseload" needs, but will use energy from ISEP as a mid-range (or "intermediate") power source, as studies have shown that is the area with the most urgent need for utilities. Access to CAES generating capacity would offer the utilities a very flexible tool to help them manage their energy costs and maximize the value and usefulness of their renewable energy assets. McGill estimated that CAES plus wind energy from ISEP could account for 20 percent of the energy used in a year at a typical Iowa municipal utility, and could save the cities and their utilities as much as $5 million per year in purchased energy. The cost of energy from ISEP CAES facilities has been estimated at $65 per megawatt-hour.

The ISEP storage structure would function much like an underground inverted "bowl" with the rim in water and acting as a seal, with the reservoir under an "oval" land parcel measuring approximately 8,000 feet x 6,000 feet; the reservoir will be about 2,800 feet deep at the crest and 2,900 feet deep at the edges.

ISEP will complete a number of additional steps prior to the official startup of the facility. John Bilsten, Vice President of ISEPA and General Manager of Algona Municipal Utilities, which will be part of the ISEP network, detailed the timeline for the project:

A supplemental seismic survey will be undertaken in January 2007. Initial ownership/investor arrangements are scheduled to be finalized in July 2007. Drilling of an investigation well and a water pump test are planned for completion by January of 2008, and preliminary design work is to be finished in May 2008. Permitting with the Iowa Utilities Board is targeted for completion in September 2008. Detailed design work would be completed by April of 2009, with financing completed in May 2009. Construction is to be completed by May 2011, with commercial operation to begin about July of 2011.