Dig Energy, a New Hampshire-based startup, has raised US$5mn in venture funding to bring its compact geothermal drilling technology into pilot deployment.
The funding round was co-led by Azolla Ventures and Avila VC, with additional backing from Conifer Infrastructure Partners, Suffolk Technologies, Mercator Partners, Koa Labs, and earlier supporters Baukunst and Drew Scott. The company also received recognition and support from Suffolk Technologies’ BOOST accelerator and the U.S. Department of Energy’s EPIC Prize programme.
Heating and cooling account for around 35% of global energy use, still mostly powered by fossil fuels. With rising energy prices and pressure on the power grid, Dig’s founders turned to geothermal heating and cooling as a more sustainable solution. Their goal is to unlock the potential of this energy-efficient method by solving the high costs and complexity of drilling.
Geothermal heat pumps tap into the consistent underground temperature just a few hundred feet below the surface, offering year-round comfort by turning the earth into a natural thermal battery. Although the technology is proven and highly efficient, adoption in the U.S. remains under 1%, largely due to expensive and oversized drilling equipment originally built for oil and gas.
Dig’s innovation is a compact drill designed specifically for geothermal use. Instead of costly carbide bits, it uses high-pressure fluid drilling, cutting costs by up to 80%. This change makes geothermal systems more accessible and scalable across all types of buildings.
“The heat beneath our feet is abundant, reliable, and always on,” said Dulcie Madden, Dig Energy CEO. “Our purpose-built, reliable, robust drill finally unlocks the most efficient on-site source of heating and cooling for buildings.”
Johanna Wolfson, General Partner at Azolla Ventures, added, “Dig holds potential to finally make geothermal heat pumps – by far the most efficient way to heat and cool buildings – cost effective to install.”
With its new funding, Dig Energy will move into pilot installations while promoting awareness about geothermal energy’s potential. The company aims to make sustainable heating and cooling a viable, cost-competitive choice for developers, building owners, and communities worldwide.