A new project at the U.S. Department of Energy’s (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) (Berkeley, California) seeks to enable the conversion of geothermal production from steady production rates to flexible or variable mode.
Flexible-mode geothermal production could then be used as a supplement to intermittent renewable energy sources such as wind and solar, which are not available around the clock, the researchers explain. In turn, this could significantly reduce the costs of storing that energy.
The technical challenges are considerable since grid demands may require rapid changes, such as reducing production by half within minutes and then restoring full production after a few hours. Such changes could lead to mechanical fatigue, damage to well components, corrosion, and mineral deposition in the wells.
“A better understanding of the impacts of flexible-mode production on the reservoir-wellbore system is needed to assure safe and sustainable production,” says Jonny Rutqvist, a Berkeley Lab scientist leading the research.
Berkeley Lab says it will adapt a suite of their modeling tools for wellbore and geothermal reservoir integrity. These tools include T2WELL, which models fluid flow and heat transfer in wells, and TOUGHREACT—which simulates scaling and corrosion. These tools will be integrated with geomechanical tools into an improved thermal-hydrological-mechanical-chemical (THMC) model to address specific problems.
“This will provide the necessary tools for investigating all the challenges related to flexible-mode production and predict short- and long-term impacts,” Rutqvist says. “The advantages to California are many, including greater grid reliability, increased safety, and lower greenhouse gas emissions.”
For the project, the Berkeley Lab researchers will be working with Calpine Corp. (Houston, Texas), which has the largest commercial operation at The Geysers in California. Calpine will contribute data, as well as access to their sites and models. The project builds on a wide variety of prior research at Berkeley Lab funded by the DOE’s Geothermal Technologies Office.
Source: Berkeley Lab, newscenter.lbl.gov.