Geothermal energy development in Minnesota and around the country has received a multimillion-dollar boost from the Department of Energy for projects ranging from an ice sheet in Eagan to carbon sequestration and heat capture at the University of Minnesota.

The funding, part of the American Recovery and Reinvestment Act, totals $338 million, of which more than $7 million will be spent in the state.

Geothermal energy is generated in the Earth's core. In its common conception, this energy can be recovered as steam or hot water and used to heat buildings or generate electricity.

The ice sheet project at the Eagan Civic Arena is part of a program to develop ground source heat pumps. The idea is to capture and circulate the heat produced by the compressors that make the ice. The government grant is for $1.34 million, and the City Council will be asked to match it, said Cherryl Mesko, Superintendent of Operations for the Eagan Parks and Recreation Department.

"We are approaching this to see if it can be done," she said. "The typical payback on a project like this is 20 to 30 years. By pulling out some components, our potential payback is 10 to 12 years, which is significant." Harris Companies of St. Paul is serving as the project consultant.

Carbon sequestration
At the University of Minnesota, assistant professor Martin Saar of the geology and geophysics department received a grant for $1.55 million as part of a project to explore the use of geothermal heat to generate electricity via carbon sequestration.

CO2 is pumped deep into the ground, perhaps in areas vacated by natural gas or oil deposits, and is heated geothermally. A small portion of CO2 is brought to the surface in its heated form and the heat drawn off to generate electricity. CO2 is then pumped back into the system.

Whether it will work or not in Minnesota, with its dense substrata, is a question the research team hopes to answer. "Ideally we think you need high permeability and porosity for better CO2 sequestration," Saar told me. "Then an overlay of cap rock of low permeability."

That's not a recipe for much of the state's ground, but sites in North Dakota and Illinois are promising, he said. In Minnesota, the Midcontinent Rift System will be investigated, he said.

The Minnesota Geologic Survey, under the direction of Harvey Thorleifson, will participate in a $17 million project headquartered at Arizona State University. Forty-one state geologic surveys will take part in a data collection project for the National Geothermal Data System (NGDS) to compile relevant state specific geothermal information.

Honeywell received nearly $4 million for work at three sites around the country, including Plymouth, for what the DOE called developing "new technologies to control directional drilling that withstand high temperatures and pressures in hostile well drilling environments."

The final details of each project are subject to tinkering and negotiation with the grant-getter and the DOE. In all, 123 projects [PDF] in 39 states received grants.