Why are scientists setting off small-scale explosions inside 1-foot cubes of plexiglass? They're watching how fractures form and grow in a rocklike substance to see if explosives or propellants, similar to jet fuel, can connect geothermal wells in a predicable manner.
Geothermal energy 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 challenges to wide adoption.
One challenge is that there are only a few places in the U.S. that naturally have the right combinations of hot rock close to the Earth's surface with available underground water. Another challenge is the initial start-up cost of drilling and connecting geothermal wells. Eric Robey, a Sandia mechanical engineer, is leading a team to explore if explosives can reduce those two challenges.
"Our goal was to come up with a new way of creating a geothermal fracture network that you have a clear idea where it is going to go it's steerable and manageable and you are utilizing fewer resources and being more environmentally friendly," Eric said. "This is where explosives and propellants come in. The idea is that they'll allow us to get away from pumping a lot of fluid down the wells. We're collaborating with Lawrence Livermore National Laboratory to model the explosions and improve the predictability of forming fracture networks."
Starting with 1-foot cubes of plexiglass, which mimic many of the properties of rock, the team watched the explosion shockwave ripple through the cube and listened with specialized microphones to the formation of tiny fractures. The team is using the information on the location of the fractures and the timing of fracture formation to refine existing computer models of underground explosions.
