Batteries not included

Wind energy is the fastest growing source of electricity in the world today. Advances in turbine design have succeeded in making the cost of wind-generated electricity competitive with coal and natural gas. Wind's intermittent nature remains a major challenge. Finding ways to make wind energy more reliable and dispatchable (i.e. deployable when needed as opposed to only when the wind blows) is that technology's holy grail. One approach to solving this problem is finding ways to "store" the energy generated from wind turbines. For example, wind generated electricity can be used to break apart water molecules (H₂O). The hydrogen (H) can be captured and "stored" in fuel cells. Wind energy can also be used to pump water into elevated tanks, and the water released to the forces of gravity when needed to power generators.

A municipal utility in Iowa is well on the way to constructing a plant designed to store compressed air generated by wind energy -- another promising technique. This is an important project that illustrates a comprehesive systems approach to problem solving. (GW)

Wind energy/storage plant slated for Dallas County

By David Elbert
Des Moines Register
January 5, 2007

Iowa’s municipal utilities announced plans Friday to build a $200 million power plant west of Dallas Center that will store wind energy in the ground and use it to generate up to 268 mega-watts of electricity.

The announcement culminates more than four years of study and research, although operation of the plant is still several years away.

Construction of the Iowa Stored Energy Park would begin in 2009 with completion of the plant expected in 2011, said John Bilsten, general manager of Algona Municipal Utilities and vice president of the newly formed Iowa Stored Energy Plant Agency.

Financing would be similar to methods used to build other utility power plants. The agency would pre-sell contracts to municipal utilities and others interested in buying the power and then use those contract to sell bonds to provide the money needed to cover construction costs, Bilsten said.

The site is roughly 40 acres of farmland located between U.S. Highway 169 and Dallas Center. Roughly 3,000 feet below the farmland is a porous rock structure that extends out for about a mile or more and has the capacity to hold compressed air pumped into the ground. That capacity is the key to the storage facility.

Backers of the project had originally considered sites with similar geological properties in the Fort Dodge area but decided the structures in that area would not work as well as the Dallas County rock formations, Bilsten said.

The Dallas County site has not yet been purchased but landowners in the area are agreeable to the location, Dallas Center Mayor Mitch Hamilton said at a news conference announcing the project.

Bilsten described how the project will work.

He said electricity will be generated by wind energy farms at remote sites and will be carried by transmission lines to giant compressors located at the storage site.

The compressors will pump the air into the ground, where it will be stored under pressure in the porous rock. The pressure is created by displacing air that is already in the rock. Air is contained within the rock by a surrounding solid rock cap.

The air can be converted back into electricity by releasing the pressure, allowing the air to drive turbines that create electricity.

The project would employ 300-400 workers during construction and create about 20-40 permanent jobs. The permanent jobs would be skilled jobs with good pay, Bilsten said

Only two similar wind storage plants are currently in existence. One is in Germany and the other in Alabama. Both are about half the size of the plant planned for Dallas County, Bilsten said.

Business Editor David Elbert can be reached at (515) 284-8533 or delbert@dmreg.com