Dig Energy, a startup on a quest to vastly improve geothermal drilling, has completed its first commercial project, digging seven boreholes for a geothermal heating and cooling system at the headquarters of Boston general contracting firm Suffolk Construction.
Dig first stepped into the public eye almost exactly a year ago, when it announced a $5 million funding round after some five years of developing its technology behind the closed doors of a barn in New Hampshire. At the same time, Dig was selected to participate in Boost, an accelerator program run by Suffolk Technologies, the venture capital affiliate of Suffolk Construction.
Dig's innovation: a rig purpose-built to drill geothermal boreholes with less noise, less water usage, and far lower cost than conventional drilling equipment.
Geothermal systems, which use all-electric heat pumps to tap into thermal energy stored underground, are widely hailed as the most efficient way to warm and cool buildings. However, the upfront price of accessing this clean source of energy can be a major barrier. The expense of installing a geothermal system can be up to five times that of an equivalent air-source heat pump. Only about 1% of buildings in the United States use geothermal systems for heating and cooling, estimated Dig Energy co-founder and CEO Dulcie Madden.
Dig says its technology could upend this math, cutting the cost of drilling by up to 80% as compared to conventional geothermal drilling. The companies declined to share specific numbers, but Dig "put some early proof points out there that, from a cost and schedule perspective, they're going to be very competitive in the market," said Parker Mundt, a partner at Suffolk Technologies.
In the standard process, the borehole is drilled first, typically with a metal bit or compressor, and shored up along the way with a casing to prevent collapse before a heat exchange pipe is inserted.
Dig's system, by contrast, uses a high-pressure nozzle that sprays water at 10,000 pounds per square inch to bore through soil and rock. The approach was explored by the oil and gas industry decades ago, but never gained traction because it didn't increase productivity in those sectors, Madden said. She and her partners saw an opportunity to adapt the idea for geothermal and spent years honing the technology.
"It's a known industry practice that's being adopted in a novel way for the first time," Madden said.
