Researchers in the United States proposed drilling through rock with a nuclear-powered tunnelling machine in the 1970s. Various experiments have led to the construction of a rock-melting drill more than a decade ago. Some firms were interested, and “serious consideration was given to use the device as a lunar drill for the Apollo flight series,” according to the new study, but the proposal never progressed beyond a prototype.
Petra, a start-up inspired by that concept, claims to be working on technology that would allow it to cut through rock without crushing it. In Oakland, California, the company first tried cutting through rock using a plasma torch in 2018. At temperatures above 10,000 degrees Fahrenheit, a bigger plasma torch was used to cut through stone slabs.
Petra later abandoned plasma in favour of a gas-and-heat mixture that exceeds 1,800 degrees Fahrenheit and fractures rock into small bits. Sensors attached to little rods make contact with the rock, but the excavation is done by heat and gas. Petra intends to use this technology, which was developed by Elon Musk, to make digging through bedrock affordable enough to enable utilities to bury electricity and other lines underground.
According to Petra CEO Kim Abrams, the company wants to cut the cost of burying utility lines by 50 to 80 percent, making it a realistic choice. However, she refuses to reveal any information on the gas-heat blend, claiming that it is proprietary.
“Every method that’s commercially available is a high-contact method that grinds up the Earth it contacts in order to remove it,” Abrams says. “This is a completely new way to the tunnel.”
Petra is now investigating if the method works on other stone types, including limestone or granite.
Overall, I think it is great. By burying more power lines, the United States may enjoy unlimited power. And, of course, having access to the area beneath our feet opens up a world of possibilities.