Going faster and deeper will require advances in drilling technologies.
Companies are developing drilling tools that are more stable when breaking hard rock at higher temperatures.
Some companies are aiming to penetrate rock without even using standard drills.
Quais, a company affiliated with the Massachusetts Institute of Technology (MIT), is using a technique called millimeter wave drilling. The frequency is similar to microwave.
The application of QUAIS involves “sending electromagnetic waves in the microwave millimeter wave spectrum through rock to essentially melt and vaporize it,” explains Harry Kelso, communications manager for QUAIS.
Traditional geothermal energy clusters around hotspots on the Earth’s surface where very hot rocks are easily accessible.
“Millimeter wave drilling really enables you to access super-hot geothermal anywhere in the world,” says Kelso.
While Quays plans to use some conventional drilling at the project site it is developing in Oregon, Kelso says conventional drills tend to break down more quickly when they reach very hard rock.
Changing drill bits increases the cost and time of drilling.
In the case of Quays, Kelso says, “Millimeter wave drilling really changes it because we’re not using a physical drill bit.”
Other companies are also working on advanced drilling technology, such as projectiles that travel several times faster than the speed of sound.
Another important resource in this process is water. While some types of next generation geothermal may pose a risk of water contamination or excessive consumption, careful design can avoid this problem.
Kay’s system requires a lot of water initially, but according to Kelso, once water is in the system it continuously circulates over the super-hot rocks.
“We’re basically recycling water over and over again,” he says.
Quais continues to raise funds with the goal of having its Oregon project operational by 2030.
Like other early versions of geothermal systems, it is an expensive project to get up and running.
“The economics are somewhat challenging,” admits Kelso. “Geothermal is still more expensive today because you’re not getting as much electricity from the well as you would if you were using that well for fossil fuels.”
But Qaiz hopes that targeting much higher temperatures, between 300C and 500C, will improve the economics.
While the high end of that temperature range is ambitious, it’s a case of hotter-the better.
According to Kelso, “This allows you to get 10 times more energy per well from geothermal, which transforms the economics and power efficiency of geothermal.”
