NEW GEOTHERMAL PLANT COULD SEQUESTER CO2 TO BOOST POWER

Karen Frantz
GHG Monitor
12/20/13

Scientists from the Lawrence Livermore National Laboratory, the Ohio State University and the University of Minnesota said last week that they are designing a new kind of geothermal power plant that will store CO2 emissions underground “and use it as a tool to boost electric power generation by at least 10 times compared to conventional geothermal power.” The approach is a new twist to existing technology that has already been used in a small number of states, mostly in California and Nevada, and researchers said they hope it could expand the technology to more areas.

According to LLNL, the new plant design “resembles a cross between a geothermal plant and the Large Hadron Collider: It features a network of subsurface concentric rings of horizontal wells inside which CO2, nitrogen and water circulate to draw heat from deep below the ground up to the surface, where it can be used to turn turbines and generate electricity.” The design is different from traditional geothermal plants in that water is partly replaced with carbon dioxide, which mines heat from the subsurface more efficiently than water, researchers said.

The team developed the system using computer simulations, which found that it could produce up to a half a gigawatt of electrical power projected and that it could “sequester as much as 15 million tons of CO2 per year”—about the same as the yearly emissions from three medium-sized coal-fired power plants. “One of our key objectives when we began developing the CO2 plume geothermal technology was to find a way to help make CO2 storage cost effective while expanding the use of geothermal energy,” said Jimmy Randolph, a postdoctoral researcher from the University of Minnesota’s Department of Earth Sciences. But researchers cautioned that the plant would “probably have to be connected to a large CO2 source, such as a coal-fired power plant, which was scrubbing the CO2 from its own emissions,” according to a LLNL news release. “That connection would likely be made by pipeline.”