Geothermal energy potential larger than previously estimated
April 23, 2012
The geothermal potential below the surface of Minnesota is three times larger than was once believed.
That’s the major finding of researchers from the University of Minnesota Duluth Natural Resources and Research Institute and the University of North Dakota. In a report released in late March, researchers concluded that Minnesota is sitting on a “clean, baseload power source.”
Geothermal energy is derived from heat stored within the Earth. Its sources are heat from when the planet was formed, along with the radioactive decay of minerals. The flow of geothermal heat, strongest at the Earth’s core, naturally begins at the center of the planet and moves toward its surface, said Don Fosnacht, NRRI center director and lead investigator.
In Minnesota, geothermal heating already is used in household heating. These new findings, however, suggest that the energy source could be tapped to produce electricity as well.
Household heating needs can be met at relatively shallow depths, said Fosnacht. But previous study of the state’s geothermal possibilities led researchers to believe that drilling to depths of 10 kilometers would be necessary to reach temperatures of 110 to 115 degrees Celsius – the temperatures necessary for geothermal energy to be used for electricity generation.
The newly released research shows the mean heat flow to be 10 percent higher than thought and shows that the necessary temperatures can be reached at depths of 6 or 7 kilometers, which is similar to the depths required to tap the resource in neighboring states.
“This is good news because we now know that Minnesota has more heat and electrical power potential as an alternative energy source on an industrial scale,” said Fosnacht in a news release. “We also learned that the cost to drill will be lower than expected because the depths to reach energy are shallower than once thought.”
Electricity produced from geothermal energy is considered to be relatively clean. While there are some greenhouse gases released from geothermal wells, the emissions are much lower than those emitted by the so-called greenhouse gases, according to information from Wikipedia.
Recent advances in deep drilling also make geothermal energy more accessible than ever. The technology to reach the necessary depths already is being utilized to extract natural gas trapped in shale, said Fosnacht in a telephone interview.
Researchers gathered data from more than “100 mining exploration drill holes and 795 water wells throughout Minnesota,” according to information from NRRI.
The report could have significant implications for the future, as government mandates require a higher percentage of power generation come from alternative or “clean” energy. In 2007, the Minnesota Legislature passed a renewable energy mandate. It requires that all state regulated utilities generate 25 percent of their energy from renewable or alternative energy sources by the year 2025.
There are other advantages to geothermal electricity as well. One such advantage is that geothermal electricity production wouldn’t require vast areas for coal storage.
“(Geothermal electricity generation) would require a much smaller footprint than a coal powered plant,” said Fosnacht.
This study will provide a basis for utility planners to assess how and if geothermal might fit into the renewable energy picture. Researchers note that planners can access information online to see how this energy could be used to help reach renewable energy targets.
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