Quaise Energy has announced the final close of its Series B financing, raising a total of US$180mn in equity — a further signal of the influx of capital into geothermal energy in the USA.
The Series B round brings Quaise’s total funding to date to US$280mn.
The proceeds will fund Project Obsidian, the world’s first commercial superhot geothermal power plant, and accelerate the commercialisation of Quaise's millimetre wave drilling system toward depths in excess of 5 km.
The latest funding round also includes a US$35mn investment from international land drilling contractor, Nabors Industries.
As well as funding, Nabors Industries has entered into a strategic framework agreement that supports Quaise’s mission to make superhot geothermal a commercial reality, beginning with the development of the flagship Project Obsidian.
“We are unlocking the most powerful clean energy source on Earth, and the Series B signals deep conviction across a wide range of investors,” said Carlos Araque, CEO and President, Quaise Energy.
“Nabors is an invaluable partner as we move millimetre wave drilling to full commercial operations at Project Obsidian and beyond.”
Key highlights:
• Final close of Series B to advance the commercialisation of superhot geothermal energy, funding Project Obsidian and the continued development of Quaise’s millimetre wave drilling system
• Nabors Industries and Quaise deepen relationship with strategic framework agreement spanning drilling operations, technology integration and commercial development
• Series B brings Quaise's total funding to date to $280 million
Drilling expertise
Nabors’ investment builds on an existing relationship with the company, and the strategic framework agreement spans drilling operations, technology integration and commercial development.
It gives Quaise access to a dedicated land rig and Nabors’ advanced platform that integrates reservoir modelling, well design and drilling strategy.
As its drilling programme advances, shared data and operational experience are expected to enhance drilling performance, reduce costs, and expedite the project timeline.
“Superhot geothermal has the potential to make clean energy ubiquitous. That is why we are excited about our close relationship with Quaise,” said Anthony G. Petrello, Chairman, President and CEO, Nabors Industries.
“Quaise’s millimetre wave technology changes the equation entirely by reaching superhot rock at temperatures and depths that are inaccessible with conventional drilling, transforming geothermal from a location-dependent resource into a global energy solution. Combined with Nabors’ drilling expertise and infrastructure, we see a path to gigawatt-scale geothermal power that no other company can offer today.”
Capital inflows
The financing is the latest in a string of sizeable investments backing the development of next-generation geothermal technologies in the US, as investors increasingly look to the sector as a source of reliable, around-the-clock clean power.
The growing flow of private capital is also helping move geothermal beyond early-stage technology development and towards commercial-scale projects.
The Series B round's first close, announced in July 2026, was led by Prelude Ventures, with strategic investments from JERA Co., Inc. and Idemitsu Kosan, two of Japan's largest energy companies.
BofA Securities and Goldman Sachs & Co. LLC advised on the fundraise.