ENERGY SECURITYModeling Geothermal Systems’ Viability
Geothermal power has a lot of promise as a renewable energy source that is not dependent on the sun shining or the wind blowing, but it has some obstacles to wide adoption. One challenge is that a limited number of locations in the U.S. naturally have the right conditions: hot rock relatively close to the surface and with plentiful groundwater to heat up. Web tool looks belowground for an economically viable renewable energy source.
Geothermal power has a lot of promise as a renewable energy source that is not dependent on the sun shining or the wind blowing, but it has some obstacles to wide adoption. One challenge is that a limited number of locations in the U.S. naturally have the right conditions: hot rock relatively close to the surface and with plentiful groundwater to heat up.
Closed-loop geothermal is one way to use hot, dry rock to heat circulating fluids to generate electricity or to directly heat buildings, a way that is being reexamined after being dismissed in the ’80s for being too inefficient. A team composed of experts at several national laboratories recently finished a two-year effort to computationally model closed-loop geothermal systems.
With closed-loop geothermal, building a system that can extract enough heat from the deep earth to be cost-effective is difficult, said Mario Martinez, a mechanical engineer and the principal investigator for the project at Sandia.
“The subsurface, the rock, becomes hotter the deeper you go, so it is beneficial to go deep,” said Martinez, who recently retired. “That hot water can be used for district heating, so you can use it to heat houses and buildings, or you can use it to generate electricity.”
Sandia led the computational modeling of the belowground system, while the National Renewable Energy Laboratory used the numerical results to estimate the economic viability of the system through their aboveground power plant and economic model. The overall project was led by Pacific Northwest National Laboratory and mechanical engineer Mark White. Anastasia Bernat, a PNNL data scientist, integrated the Sandia and NREL models into a publicly available web tool to allow startup developers and venture capitalists to explore the economic viability of various closed-loop geothermal system designs. Idaho National Laboratory shared variables from a prototype geothermal system at the lab and studied various possible enhancements to closed-loop geothermal systems to improve their economic viability.
The researchers shared their results in a paper published recently in the scientific journal Geothermics. The DOE Geothermal Technologies Office supported the research.
