Extreme Geothermal Drilling Studied

Kenneth Oglesby is looking to make a deep impact on ground-source energy.
The technology Oglesby is studying involves drilling holes 30,000 feet into the earth and tapping the heat from rocks as hot as 572 degrees Fahrenheit.
“We are talking hot, hot,” Oglesby said.
The owner of Tulsa-based Impact Technologies believes in the potential of drilling two-inch holes six miles down to molten rock and using that heat to power cities.
Last month, the U.S. Department of Energy awarded a $2.4 million grant for the development the drilling technology that creates small holes at high speed. Oglesby has already spent $4 million on development and testing this technology, so the grant is expected to extend that development into these deeper and hotter applications.
The grant, part of a $338 million package of DOE awards, was part of the $787 billion American Recovery and Reinvestment Act. That economic stimulus package, signed into law a year ago, included cash for other “green” technologies, such as high-speed commuter rail and electric cars. The grant is a milestone for Oglesby, who has been researching drilling techniques either on his own or for companies like Chevron Corp. since the 1970s.
Oglesby proposed to DOE the idea of drilling many holes into the earth from one central shaft, he said.
“Then, make that heat-transfer process, using that heat to generate steam, which will spin turbines and generate electricity at each site as possible,” Oglesby said.
Drilling small holes, even an inch or two in diameter, at that depth faces huge obstacles. Overcoming the heat and pressure generated at a depth of 30,000 feet is difficult, Oglesby said.
“We have to figure out what kind of materials we need for the drills and the pipes,” he said. “The challenge is to create the equipment to handle the heat at that pressure. It is doable.”
Drilling companies have struck molten sulfur in western Oklahoma. Geothermal is cost-effective in places such as California, because the hot source rock is closer to the surface — a few thousand feet instead of six miles.
Impact has been working with DOE on developing this drilling technology for many years. The drilling equipment shoots abrasive particles at high speed, which cuts through rock and steel. The technology is faster and more powerful than current drilling. For this project, Impact is teaming up with the Lawrence Berkeley National Laboratory and Missouri University of Science and Technology to create the micro-hole heat transfer arrays with holes fanning out from a central hole, Oglesby said. Impact Technologies will also work with the University of Tulsa on the tubular designs required.
“Deep geothermal power potential is everywhere. At shallow depths you see ground-source heat pumps lowering utility bills right now. But the deep thermal power, at the 30,000 foot depths they are talking about, is available anywhere in the world to generate electricity.” Impact Technologies’ technique will improve the heat transfer of these systems at a lower cost and allow the overall system to be more efficient — possibly gaining the same heat and generated electricity at shallower depths.
Impact Technologies’ technique allows drilling to be efficient, gaining the same heat at shallower depths.
Impact Technologies’ method of drilling attracted the DOE, said Michelle Witt, the company’s director of business development.
“That is why DOE was looking at our technology,” Witt said.
The company has six employees who design, patent and build prototypes for specialty drilling rigs in addition to commercializing the technology and running daily operations. The DOE grant will last three years and be used to test the concept, which Oglesby said, is already about 15 years in the making.

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