There are vast geothermal reserves in the top 10 kilometers of the Earth's crust, essentially waiting for human energy consumption to begin tapping into its generous power output, but it does not itself produce greenhouse gases. However, geothermal sources currently produce only three-thirds of 1% of the world's electricity. This promising energy source has long been limited by the extraordinary challenges of drilling holes deep enough to access the intense heat beneath the earth's surface.
Now, an MIT spinoff company has announced that it has found a solution with an innovative technology that can dramatically reduce the cost and schedule of drilling to incredible depths. Cambridge, Mass.-based Quaise Energy plans to deploy so-called gyroton drills that use powerful microwaves to vaporize rock.
“For geothermal energy to be usable outside of places like Iceland, it needs to go deeper and hotter.” —Carlos Arake, Quaise Energy
Gyrotrons use high-power linear beam vacuum tubes to generate millimeter-long electromagnetic waves. Invented by Soviet scientists in the 1960s, gyrotons are used in fusion research experiments to heat and control plasma. Quiz Inc. has raised $95 million from investors including Japan's Mitsubishi Motors to develop technology that allows it to drill 20 kilometers deep, closer to the Earth's core than ever before, quickly and efficiently.
Quaise Energy has developed a prototype portable gyrotron and plans to conduct field tests later this year.quasi-energy
“Supercritical geothermal power has the potential to displace fossil fuels and ultimately provide a pathway to an energy transition to carbon-free baseload energy,” said Dr. said Quise CEO Carlos Arake, a former technical director in the oil and gas industry. Engine Accelerator is MIT's platform for commercializing world-changing technologies. “For geothermal energy to be usable outside of places like Iceland, it needs to go deeper and hotter.”
This deepest man-made hole extends 12,262 meters below the surface of Siberia and took almost 20 years to excavate. As the shaft went deeper, progress slowed to less than 1 meter per hour, and when the work was abandoned in 1992, the speed finally decreased to zero. This effort and similar projects have shown that conventional drills cannot match the high temperatures. and deep crustal pressure.
Microwave and stone meet
“But energy beams have no such limitations,” says Paul Waskow, a senior research engineer at MIT's Plasma Science and Fusion Center. Woskow spent decades manipulating powerful microwave beams, guiding them to precise locations to heat the hydrogen fuel to more than 100 million degrees Celsius and initiate the fusion reaction.
“It wasn't much of a leap to think that if you could melt a steel chamber and vaporize it, you could also melt rock.” —Paul Waskow, MIT
“We already knew that these sources would cause significant damage to the material, since one of the challenges is not to melt the internal chamber of a tokamak, which is a device that uses a magnetic field to confine plasma.” So it wasn't a huge leap to make the connection that if you can melt a steel chamber and evaporate it, you can also melt rock.”
In 2008, Waskow began intensive research into whether this approach could be an affordable improvement to mechanical excavation. This research led to Woskow's practical experiment in using a small gyrotron to blast basalt bricks.
Based on experiments and other research, Waskow calculated that a millimeter-wave source targeted through a waveguide about 20 centimeters long could punch a basketball-sized hole in rock at a speed of 20 meters per hour. If continued drilling continued at this rate, the world's deepest hole would be formed in 25 and a half days.
“It was clear that if we could make this work, we could drill very deep holes at a fraction of today's costs,” Wostoff says. Wostoff is credited as the founder of Quaise, but unlike MIT, he has no financial interest in the company, he said.
waves of possibilities
Quaise's design calls for a corrugated metal tube to act as a waveguide, which is removed after drilling is complete. This system utilizes injected gas to rapidly cool and expel the ash.
“Instead of pumping liquid and turning a drill, we burn the rock and evaporate it to extract the gas, which is much easier to pump than mud.” —Carlos Arake, Quaise Energy
“It takes about megawatts to power it, which is the same amount of energy as a typical drilling rig,” Arake says. “But we're going to use it in a completely different way. Instead of pumping liquid and turning a drill, we'll burn rock and evaporate it to extract the gas, which is much easier than mud. You can pump it.”
By using waveguides to direct the energy into the target rock, the energy source can be kept at the surface. It may sound like a stretch, but this concept was tested in his experiments in the 1970s when Bell Labs built his 14 km waveguide transmission medium in northern New Jersey. Researchers have discovered that millimeter waves can be transmitted with little attenuation.
Quaise will initially target industrial customers who require steam with guaranteed flow rates, temperatures and pressures. “Our goal is to match industrial load specifications,” he says Araque. “They can remove the boiler, but we give them 500C steam on site.”
Ultimately, the company believes the technology could enable new geothermal power plants or reuse turbines previously heated with fossil fuels, generating an estimated 25 to 50 megawatts of electricity from each well. The hope is that it will be able to feed into the power grid.
The company plans to begin field demonstrations this fall at a site in Marble Falls, Texas, using a prototype device to drill holes in solid rock. From there, Quise plans to build a full-scale demonstration rig in the high geothermal region of Texas. Western United States.
Quiz Energy drilled a hole in the basalt column 254 centimeters (100 inches) deep and 2.5 centimeters in diameter, 100 times deeper than the team's first experiment at the Massachusetts Institute of Technology (MIT). It became.quasi-energy
facing the depths
Although laboratory data demonstrate the scale-up feasibility of this approach, the technical obstacles to the QUISE program may run deeper than its radical drilling method.
“If we could actually drill a 10km hole using high-power microwaves, that would be an important engineering achievement,” said Jefferson Tester, who studies geothermal energy extraction in underground rock reservoirs at Cornell University. ” he says. “But the challenge is completing the well in a way that doesn't fall apart, especially when you start removing fluids from the subsurface and changing the temperature profile.
“Drilling holes is hard enough,” Tester says. “But actually operating a reservoir and safely extracting energy from the ground may be a very distant future.”
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