Geothermal energy has long been hailed as a clean, renewable power source, but its full potential remains untapped. While today’s geothermal plants operate at temperatures between 100 and 250°C, scientists aim to push these limits.
Recent breakthroughs suggest that tapping into superhot rock—above 375°C—could revolutionize the energy landscape, delivering power up to ten times more efficiently than current systems.
Daniel W. Dichter, a senior mechanical engineer at Quaise Energy, is at the forefront of this research. His recent studies, presented at the 2024 Geothermal Rising Conference and the 50th Stanford Geothermal Workshop, explore how geothermal plants could be adapted to work with temperatures starting at 300°C.
The findings provide a roadmap for designing plants capable of harnessing the immense energy stored in superhot rock.
Geothermal cooling system for a house in hot parts of the world
In geothermal plants, water absorbs heat from hot rock and is brought to the surface to generate electricity. Daniel W. Dichter found that for superhot geothermal systems, water doesn’t need to stay above 375°C all the way to the surface. Additionally, fluids above 300°C can use standard, cost-effective turbines to produce electricity, unlike lower-temperature systems that rely on more expensive, less accessible turbines.
When water is pumped into rock hotter than 375°C, it turns into supercritical water, a phase that can carry 5-10 times more energy than regular hot water. This energy-dense steam-like state could generate electricity efficiently if brought to the surface.
However, such extreme heat is only found in a few places, like Iceland, where the superhot rock is near the surface. In most locations, this rock lies 2 to 12 miles underground, beyond the reach of standard drilling tools, which can’t withstand the intense heat and pressure. Drilling deeper also becomes increasingly expensive.
To overcome this, Quaise Energy is developing cutting-edge drilling technology that uses millimeter-wave energy to vaporize rock, allowing it to reach depths of up to 12 miles.
Dichter’s research highlights several promising insights. For instance, supercritical water—formed when exposed to temperatures above 375°C—can carry 5-10 times more energy than conventional hot water.
However, his work shows that maintaining supercritical conditions all the way to the surface isn’t necessary. Water at temperatures as low as 350°C at the surface could still produce significantly higher power outputs, simplifying system design and reducing costs.
Another key innovation involves replacing hydrocarbons with water in binary cycle systems, which convert geothermal heat into electricity.
Dichter found that water performs better as a secondary fluid at higher temperatures, and its use could lower costs while leveraging the well-established supply chain of steam turbines.
Quaise Energy’s work marks a turning point for geothermal power. By unlocking the potential of superhot rock, this clean energy source could compete with traditional fossil fuels and support regional heating and domestic applications.
“There’s a renaissance happening in geothermal right now,” says Dichter, underscoring the excitement and opportunity this field offers for a sustainable energy future.
