Did you know that one of the most ancient types of heating is geothermal? This energy has even been used in spa treatments since the third century BCE. While it is one of the most effective renewable energy sources available, it is not the most widely used source. That may all change. We can finally say goodbye to geothermal depth limits, as vaporized rocks have opened to unveil power 12 miles below.
Unveiling power 12 miles below
Summer can become very hot, but it’s nothing compared to the Earth’s core. According to New Atlas, the core’s center has temperatures of approximately 5,200°C (9,392 °F). These temperatures are produced by the decay of radioactive elements, which combine with heat from the Earth’s formation. Some say where there’s smoke, there’s fire, and the same can be said of heat and geothermal energy.
Other renewables, such as the sun and wind, do not provide energy 24/7, but Earth’s core is always hot. Unfortunately, this heat is not always easily accessible, which is probably why only 0.3% of the world’s energy consumption is provided by geothermal energy. If we could tap into this energy, it would provide literal round-the-clock, continuous clean power.
But simply drilling deep enough into the core is not as easy as it sounds, because the Earth’s crust has varying thicknesses between 3 to 47 miles. Also, one should consider the escape of harmful gases and the drill melting.
Trying everything under the sun
Researchers at MIT have tested and tried it all. According to Paul Woskov, MIT senior fusion research engineer, tapping into 1% of the Earth’s heat would meet global energy demands for more than 20 million years. The quest is thus worth the while. An MIT derivative called Quaise has turned to seized fusion technology to drill history’s deepest holes.
However, before that, researchers have turned to something commonly seen in science fiction, namely lasers. Laser beams heat, melt, and vaporize basalt rock with a method called spallation. This process was necessary during events where physical drill bits no longer operated effectively.
“A direct-energy drilling process, would offer some huge advantages: 1) no mechanical systems in the wellbore that could wear out or break, 2) no temperature limit, 3) equal ease penetrating any rock hardness, and 4) potential for replacing the need for casing/cementing by a durable vitrified liner.” – Impact Technologies president, Kenneth Oglesby, in a 2014 MIT report for the US DOE’s Geothermal Technologies Program
Finally, saying goodbye to geothermal depth limits
Problems with lasers include: Deficiency in energy and efficiency, being too expensive, and not penetrating deeper than 30 cm (11.8 in). This is why Quaise sought nuclear fusion as a solution. But once again, the process was not as simple as thought, since vast amounts of heat were needed to release safe and clean nuclear energy.
Enter the gyrotron, which can produce ongoing energy beams higher than a MW in power. In 2018, Quaise combined conventional rotary drilling with gyrotron-powered millimeter-wave technology, whilst adding argon as an inert gas. Argon cleans and cools the bore while firing rocks up to the surface. With this hybrid system, Quaise believes that holes up to 12.4 miles deep can be drilled, and the process would only take 100 days with a 1-MW gyrotron.
At the beginning of this year, the company started testing outdoors but is still enhancing its full-scale, field-deployable demonstration machines. Later this year, they will be conducting a big trial run near Austin, Texas, with hopes of drilling more than 100 meters (0,06 miles) down at a granite quarry. Should these trials have positive results, we may soon be able to tap into Earth’s clean, round-the-clock geothermal energy, redefining the global renewable energy sector and fossil-fueled power plants.