New geothermal drilling technology being explored at university in Zurich
A thermal drilling method, which will allow for reaching greater drilling depths in a more efficient and more cost-effective way, is currently being developed at the ETH Zurich.
Recent articles describe a new geothermal drilling technology currently being explored by ETH Zurich, a technical university in Zurich in Switzerland.
“With increasing depth, geothermal energy offers an almost inexhaustible potential for renewable energy. The drilling costs however, rise exponentially with depth in the case of conventional rotary drilling. A thermal drilling method, which will allow for reaching greater drilling depths in a more efficient and more cost-effective way, is currently being developed at the ETH Zurich.
Researchers at ETH Zurich are using heated oxygen, ethanol and water pumped into their reactor burner through various pipelines and valves and mix them under temperature and pressure conditions, which correspond to the supercritical state of water (see illustration below) in an effort to get to energy rich deep geothermal rock. The researchers observe the mixture’s auto-ignition through small sapphire-glass windows using a camera. A newly developed sensor plate measures the heat flux from the flame to the plate of simulated rock and records the temperature distribution on the surface for different distances between the burner outlet and the plate.
Based on the experimental results, conclusions can be drawn concerning the heat transfer from the flame to the rock. Philipp Rudolf von Rohr, professor at the Institute of Process Engineering of the ETH Zurich and supervisor of the three PhD students explains, “The heat flux is the crucial parameter for the characterization of this alternative drilling method.”
“The experimental results from the current test set-up are being used to design a pilot plant. The 1.2 million-Swiss-franc plant should demonstrate that it is actually possible to drill through rock by means of hydrothermal flames. The project is funded by the Swiss Federal Office of Energy, the industrial organization swisselectric research, ETH Zurich and the Swiss National Science Foundation.”
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