UC Berkeley drills 400-foot borehole to explore geothermal heating

Early this past Monday morning, a small team of University of California, Berkeley, engineers gathered around a two-story-tall drilling rig parked at an out-of-the-way spot on the north side of campus. As the overnight rain turned to drizzle, the team watched as a drilling crew used a massive 8-inch-wide drill bit to start punching a new borehole in the soil. By the end of the week, this borehole will extend 400 feet below ground, becoming the deepest borehole on campus and providing engineers with the first opportunity to study the properties of the bedrock that sits below UC Berkeley. They will use the information that they gather from the borehole to help determine whether a geothermal heat pump system - which uses the thermal properties of subsurface rock to help heat and cool buildings more efficiently - could be integrated into UC Berkeley's long-term plans for decarbonizing its energy system. "Nobody has ever drilled this deep beneath the campus," said Kenichi Soga, the Chancellor's Professor and Donald H. McLaughlin Chair in Mineral Engineering at UC Berkeley. "Most of the boreholes that we have on campus are used for designing new buildings and typically only go down to 60 or 80 feet. Now, we're going to 400 feet.