Mazama Energy raises $135 million to advance commercial development of ultra-hot rock geothermal energy

Mazama Energy has raised $135 million (approximately HK$105 million) to accelerate the commercial development of ultra-hot rock geothermal energy, a technology designed to generate large amounts of reliable carbon-free electricity from extremely hot subsurface environments. The company announced the new funding on September 17, which will support its work at Newberry in Oregon, including Project Athena and the U.S. Department of Energy-backed Project Ceres. Mazama plans to demonstrate electricity production by 2027 as power demand continues to rise.

The company is drilling into rock at 750°F (approximately 400°C), with each well delivering up to 10 times the output of conventional geothermal wells, which typically operate at 390°F (approximately 200°C).

Technical breakthroughs in ultra-hot geothermal systems

Mazama has already set a record for the hottest geothermal system ever built. In 2025, the company established a system at Newberry that reached 629°F (approximately 331°C), demonstrating reservoir creation, subsurface connectivity, and heat extraction. Unlike conventional geothermal development that relies on naturally occurring reservoirs, engineered geothermal systems create pathways through hot rock, allowing fluid to circulate and bring heat back to the surface. Mazama's second well in Project Athena reached a depth of 10,350 feet in September, taking just 15 days at roughly 80% of the speed of wells drilled in 2025.

The company is currently extending it to approximately one mile deep in pursuit of the 750°F target. Mazama Energy CEO Sriram Vasantharajan said: "The ultra-hot geothermal breakthrough turns extreme heat into a repeatable, economic power system. At Newberry, we have already demonstrated the key elements: extreme-temperature drilling, reservoir creation, and heat harvesting at temperatures no other engineered geothermal system has achieved. We are now advancing this integrated system for faster, more efficient, and larger-scale deployment."

At 750°F, water can reach a supercritical state with significantly higher energy density. Combined with greater reservoir productivity, this will allow Mazama's wells to generate up to 10 times the electricity of conventional geothermal wells. The company says this approach also uses 75% less water and requires 80% fewer wells than conventional geothermal development. Reducing the number of wells will lower surface infrastructure requirements and shrink the overall footprint of each project. Mazama has spent years addressing three interrelated technical challenges: drilling at extreme temperatures without damaging equipment, creating effective reservoirs where none naturally exist, and extracting enough heat to support electricity production.

Funding supports future development plans

Combining these capabilities is intended to make ultra-hot geothermal power generation scalable and cost-competitive with fossil fuels. The funding includes an oversubscribed Series B round led by Centaurus Capital and Doerr Capital. ConocoPhillips, Shell Ventures, Khosla Ventures, and Gates Frontier also participated, along with several other investors.

Some of the funding will go toward advancing Project Ceres, which will push horizontal well development in ultra-hot rock, targeting 15 MW of power capacity per well and a planned demonstration of electricity production in 2027. Beyond Athena and Ceres, Mazama is also pursuing independent certification of more than 10 gigawatts of geothermal resource potential at Newberry and evaluating other sites in the U.S. and abroad to advance multi-gigawatt developments aimed at supporting power affordability, growing demand, and global energy security.

Item	Specification
Drilling depth	10,350 feet
Ultra-hot rock temperature	750°F (approximately 400°C)
Highest geothermal well temperature	629°F (approximately 331°C)

The potential and challenges of ultra-hot geothermal energy

Mazama Energy's ultra-hot geothermal technology represents an innovative approach capable of effectively harnessing extremely high subsurface temperatures to produce electricity. The technology not only increases energy output but also significantly reduces water use and infrastructure requirements, carrying important implications for environmental protection and sustainable development. With global demand for renewable energy on the rise, successful commercialization of Mazama's technology could help reduce dependence on fossil fuels and drive the energy transition. The funding will accelerate the realization of the technology and has the potential to reshape the geothermal energy market.