It's no secret—there's a lot of energy held just a few thousand feet under Earth's surface. To harness any sizable amount of our planet's underlying geothermal energy for steam power, we would have to bore more than two miles into the crust. Unfortunately, the current drilling process is prohibitively expensive for most interested parties, ranging from $5 to 20 million depending on the depth desired.
Mark Russell, CEO of Hypersciences, wants to change that. His method? Repeatedly firing projectiles into the Earth's crust, which Russell claims is ten times faster than traditional drilling. He received a patent last year for his projectile-based system, and was recently funded about one million dollars by Shell's GameChanger program to continue his research, according to GeekWire.
The process works by loading a projectile with a special abrasive core into a ram accelerator, which serves as both the chamber and barrel of this 'earth gun.' Russell's design pumps gases into the ram accelerator, which then ignite, pressurizing the chamber as the projectile passes through. This sends the projectile into the ground at almost 4,500 miles per hour (2 km/s). At that speed, the projectile obliterates whatever unfortunate rock or sediment it hits, and the refuse is sucked back out of the hole. The projectile itself is left fairly general in the patent, but Russell postulates that it could be tipped with a plastic explosive to add more drilling power. Another option is to embed sensors to gauge temperature and exact depth.
The ram accelerator is fired over and over again, with multiple projectiles, until the desired depth is achieved; multiple ram accelerators can fire simultaneously for wider drilling or in tandem with traditional drills as well, according to the patent. Russell claims his technique saves money on tool wear and breakage, as well as the extended time traditional drilling takes. However, there are still questions surrounding how the technology will work in practice, and also what affect repeated concussive blasts could have on the sub-terrainian environment, groundwater, and geology.
The Department of Energy says that a geothermal station operating at peak levels could provide sustainable energy to 41,000 average U.S. homes. In other outside-the-box ideas, the DOE is also exploring the use of high-powered lasers to maximize the heat retained from geothermic wells.