Small-scale explosions inside one-foot cubes of plexiglass are helping Sandia National Laboratories scientists evaluate how to best use explosives and propellants to improve deep-underground geothermal energy development.
The lab’s Geothermal Research Group is using ultra-high-speed cameras that record the explosions at 1 million frames per second, plus specialized microphones to detect the sounds of tiny fractures as they form inside the plexiglass, which mimics many of the properties in rock.
The experiments are shedding more light on ways to steer and manage geothermal drilling operations that aim to crack open subsurface layers of hard granite, allowing developers to capture heat from underground hot-rock formations that can be used for electric generation, or for heating and cooling buildings and communities.
The current project is one of many research initiatives that Sandia has conducted for decades to improve drilling technology. Its experiments directly contributed in the past to modern industry methods that oil and gas companies use today to extract hydrocarbons from hard shale rock.
Geothermal energy developers are now applying those same methods to penetrate far deeper into the Earth than ever before, and Sandia wants to help make those efforts more efficient and less expensive, said Geothermal Research Group Manager Giorgia Bettin.
“The big issue with geothermal development is cost and risk,” Bettin told the Journal. “Geothermal operations require large initial investments with a lot of risk, because it’s hard to know subsurface conditions, where to drill, and how to access those deep geothermal resources.”
In the controlled-explosions project, Sandia is working with Lawrence Livermore National Laboratory, which has extensive computer models of underground explosions based on decades of experiments that started with nuclear testing in the 1960s, said Lawrence Livermore computer model expert Oleg Vorobiev.
“Eventually, the goal is to understand how to create fracture networks in hot, compressed granite at significant depths,” Vorobiev said in a statement. “This is very challenging, computationally, because events occur at different timescales. Shockwave propagation is very fast compared with microfracture formation caused by explosive gasses.”
Sandia is working with many other national labs as well to advance geothermal technology, with financing from the U.S. Department of Energy’s Geothermal Technologies Office.
“It’s a group effort across the national lab complex,” Bettin said. “We’re all working as a team because we understand how important this research is.”
That includes development of advanced tools, sensors and methodologies to characterize subsurface conditions, determine temperatures, and pinpoint hot-zone locations.
“It’s data fusion, combining different methodologies for new ways to assess conditions and get higher resolutions of what the subsurface looks like,” Bettin said. “It includes a lot of software development and data analysis.”
New methods and tools can help optimize drilling operations with real-time down-hole data.
“Live data streams can allow drillers to analyze operations on the spot,” Bettin said. “It can tell them if they’re drilling in optimal zones or if they need to alter the operation.”
Past Sandia research paved the way for development of high-temperature-resistant drilling tools, such as a specially designed and lubricated down-hole hammer needed for deep-underground drilling. The lab created a special high operating temperature, or HOT, test facility for that research that includes a 20-foot-tall drill rig, a heating chamber and a process gas heater to simulate underground conditions.
Such research is critical to move modern geothermal energy development forward, something new legislation introduced in this year’s session in Santa Fe by Sen. Gerald Ortiz y Pino, D-Albuquerque, aims to increase through local entities.
The bill, SB 8, would establish a $10 million state fund to make grants of up to $250,000 for New Mexico universities, state agencies and tribal governments to study the costs and benefits of geothermal projects, plus $15 million for low-cost loans for public and private entities. It would also authorize $600,000 in annual funding for the Energy, Minerals and Natural Resources Department to oversee grant and loan applications and promote development, plus $500,000 in annual funding for a new “center of excellence” at the New Mexico Institute of Mining and Technology in Socorro.
The funding will help EMNRD to pursue federal grants for geothermal research and development, said Tom Solomon, an environmentalist who facilitated a geothermal working group that Ortiz y Pino established last year. The group identified more than $600 million in federal assistance available for geothermal development nationwide.
“We need state-level matching funds to obtain federal assistance,” Solomon told the Journal. “That’s why we put the geothermal funding into the bill to leverage federal dollars.”
If approved, the new center of excellence could allow NM Tech to significantly expand its research on New Mexico’s subsurface geothermal resource potential, said Shari Kelly, a senior geophysicist with the state Bureau of Geology and Mineral Resources. It would also support new geothermal-related education and training opportunities for students, plus collaborative efforts among state universities and colleges to advance the industry.
New Mexico State University would directly participate in the center of excellence, complimenting NM Tech’s geological research with projects to further advance electronics, tools and machinery for deep-underground development, said NMSU Electrical Engineering Associate Professor Olga Larova.