Compressed air energy storage - the Iowa story

10 years ago | Jun 07, 2010
By: CEP Staff,
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In 2009 Kansas passed a compressed air energy storage (CAES) act, allowing the KCC develop rules and regulations on this process. In CAES technology, air from wind turbines is stored at pressure in underground rock formations, and released to create power when the wind is not blowing. A test project is already underway in Iowa. From this Des Moines Register article by Dan Piller, the project has run into its share of obstacles - mostly regulatory and financial. Iowa ranks second only behind Texas in wind energy production.

Dallas Center, Ia. " The rock under Dallas County appears to be both strong and porous enough to hold compressed air " a critical step for storing wind energy, engineering data from Iowa Stored Energy Park's first test well show. The financial picture isn't as reassuring. Stored Energy Park is an experiment that would try to solve electricity's most vexing challenge: It is used in real time and can't be put in reserve. The park would store pressurized air in underground rock formations, then release it as needed to power a 270-megawatt electricity generator.

But even if two more test wells that will be dug this summer prove the engineering worth of the project, Stored Energy Park faces a financial challenge.

"We need to raise $110,000 by October first to meet our match with the Iowa Power Fund," Stored Energy Park director Kent Holst said. Holst said the money would be needed to qualify for $875,000 from the Power Fund, the last quarter of the $3.2 million the state fund awarded the project two years ago. The grant stipulated a $500,000 match from Stored Energy, of which the $110,000 is the final piece.

Stored Energy also has received $1.5 million from the U.S. Department of Energy. Iowa's municipal utilities have also contributed $1.5 million. They would receive any surplus electricity from the project, if built. A letter was sent to Iowa's 135 municipal utilities seeking additional money, Holst said, bringing $10,000 from the Livermore municipal system. "It's disappointing," Holst said. "We could come to the end of the year and have a lot of great information, but no project."

Ray Wahle of Sioux Falls, S.D., an officer of Missouri River Energy Services, which provides electricity to municipal utilities in western Iowa, said, "If that happens, I won't need to drive all the way down here for meetings." Holst said he is confident that Stored Energy Park can raise the $110,000 by October. But that won't be the end of the financial challenge. "We need $10 million next year for the air-injection tests, and that will come from our utility members," said Holst, a former manager of Traer Municipal Utility and long the driving force behind the Stored Energy Park.

The municipal utilities have received research and now the first results of the 2,800-foot test well dug in February, which is on the south side of Iowa Highway 44 about two miles west of Dallas Center. The well showed the Mount Simon Sandstone under Dallas County can take up to 1,200 pounds per square inch of pressure and has sufficient porosity, or holes in the rock, to store the compressed air. "That's well within the zone we need," Holst said.

Two more test wells will be dug nearby this summer to validate the concept of energy storage. Stored Energy Park chose the Dallas County site because it is close to a geological formation at Redfield where Northern Natural Gas stores natural gas underground for its heavy winter use periods. The site is also close to a MidAmerican Energy transmission substation at Grimes. To date, one other stored energy facility in the United States, in Alabama, has been developed.

The underground storage challenge is just the first issue. If the engineering and geology of storage is OK, Stored Energy must then build a 270-megawatt electricity generator at up to $500 million. It then would have to be connected to the electricity grid and trade in the wholesale markets of the Midwest Independent System Operators, the cooperatives of utilities, generators and transmission operators from the Dakotas and Minnesota to Ohio.

Stored Energy also must figure its regulatory fit. Holst said the Federal Energy Regulatory Commission, which oversees the interstate aspects of transmission and generation, hasn't determined what type of energy storage facility it should be. "Are we generation or transmission?" Holst said. "The (commission) hasn't decided that yet." Iowa Gov. Chet Culver cited the significance of the stored-energy project last month at a meeting of the American Wind Energy Association in Dallas.

"In Iowa we're working on a project to do something that is new and unique in energy, a project to store wind energy for use during peak periods. This is the type of project that can have real significant for renewable energy."

--- posted by Maril Hazlett,