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The Innovative Technology Allows Melting Rocks at 700°F, Creating New Opportunities for Energy and Industrial Exploration
Geothermal energy faces challenges in expanding its potential. Most plants operate at temperatures between 100 and 250°C. This limits the efficiency and expansion of the technology. The solution may lie in so-called superheated rocks.
They are found at temperatures exceeding 375°C and can significantly increase electricity production.
The difficulty lies in accessing these rocks. Deep drilling of up to 12 miles (approx. 19 km) is necessary. This exceeds the world’s deepest hole, the Kola Borehole, at 7.6 miles (approx. 12 km).
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Illiterate or semi-literate grandmothers were trained to repair solar systems, open rural workshops, and light up homes that still depended on kerosene.
An innovative solution may be on the way. The American company Quaise Energy is developing new drilling technology using millimeter waves. This system promises to reach greater depths by melting and vaporizing rocks.
Daniel Dichter, senior mechanical engineer at Quaise, published research on superheated geothermal power plants. He states that principles of conventional design can be applied at higher temperatures.
According to Dichter, studies analyze conventional geothermal designs and adapt them for temperatures above 300ºC.
“We have a good understanding of how to design geothermal power plants in the conventional temperature domain, but we don’t have much experience with temperatures of geothermal sources above that. These papers apply conventional geothermal design principles to a higher temperature range starting at 300ºC (572°F),” said Dichter.
The Energy of Superheated Rocks
Geothermal energy depends on pumping heated water through underground rocks. Supercritical water, present at high temperatures, has more energy than conventional water. This phase resembles steam but has a higher density. This makes it a more powerful energy source.
One point raised in Dichter’s research is that maintaining supercritical water at the surface may not be essential. The study suggests that superheated geothermal systems can operate efficiently even at lower temperatures. This would make superheated geothermal energy more accessible.
Energy losses when transporting superheated water through pipes are a challenge. The higher the temperature, the more energy the water carries. However, the flow rate decreases. The study points out that the temperature gain and flow loss eventually cancel each other out.
“While the heat content of supercritical water is higher, the mass flow through the pipes decreases, and they basically cancel each other out“, explains Dichter.
Systems operating at surface temperatures of 350ºC may still be more efficient than current ones. However, maintaining the water in a supercritical state in the underground reservoir remains a relevant factor. This could ensure production even with losses between the superheated rock and the surface.
Accessible Turbines for Geothermal Energy
Another relevant discovery from the study is the use of conventional turbines for superheated geothermal energy. If the temperature of the surface fluids exceeds 300ºC, standard turbines can be used. This reduces costs and facilitates the deployment of the technology.
The research also examines the turbine systems currently in use. Binary cycles, which combine two fluids, are common in geothermal generation. Hydrocarbons are used to optimize the conversion of heat into electricity.
However, Dichter suggests that water could be a better alternative. At high temperatures, it becomes more efficient and reduces environmental impacts.
Superheated geothermal energy could benefit various sectors. Power plants, district heating, and ground-source heat pumps are among the possibilities.
“The applications are diverse, from power plants to district heating and domestic ground-source heat pumps, and there are many new eyes in the field. There is a renaissance happening in geothermal energy right now“, emphasizes Dichter.
The technology still faces challenges. Deep drilling requires technical advancements and significant investments. Heat transmission also needs to be more efficient.
Even so, experts see the potential of superheated rocks as an important step. If realized, this energy could become an even more competitive renewable source in the future.
With information from Interesting Engineering.
