The University of Minnesota and South Dakota start-up Heat Mining Co. recently struck a licensing deal over a UM innovation that could potentially, and for the first time, turn fossil fuels green.
The new technology, which UM has trademarked as CO2 Plume Geothermal, creates electric power by capturing carbon dioxide, a major greenhouse gas, and injecting it deep underground to tap geothermal energy. If successfully integrated, the invention could seriously offset the high cost of capturing CO2 in a coal-fired plant.
“That was always the problem,” says Martin Saar, an earth sciences professor at UM. “The extra cost of adding carbon capture and sequestration to a plant was so high that it was prohibitive. [CO2 Plume Geothermal] potentially turns a fossil fuel plant into a clean power plant,” Saar adds, calling the technology a possible “game-changer.”
Though the idea of capturing carbon dioxide before it reaches the atmosphere isn’t new, most plans call for the fossil fuel to be nearly extinguished upon injecting it underground.
UM’s technology, however, pumps the carbon dioxide into ultra-deep saline aquifers, where high heat and pressure put the fuel in a super-critical stage so that it becomes dense like a liquid, but remains porous as a gas. That gas is eventually siphoned from the rocks above the saline aquifer, then sent through turbines to become electricity.
Heat Mining calculates that the carbon dioxide emissions from a typical 500-megawatt coal power plant could be utilized by the technology to turn a small turbine and generate 25 megawatts of power. While company officials admit that’s not much power, they say that with more CO2 wells and compact units added to the system, there could be thousands of megawatts of extra power produced after a couple decades.
“This is an absolutely novel approach,” says company founder Ken Carpenter, “which is why the patents were filed for this technology.” Carpenter also notes that by using enough of this technology, coal and natural gas-fired power plants could become carbon neutral or even carbon negative over time.
Heat Mining and UM also plan to market the technology as a cheaper alternative to the similar technologies oil companies in West Texas use to recover trapped oil. Another idea is to use the technology as a kind of underground battery to combat the problem of intermittent power loss from sustainable sources like wind or solar farms.