Bay Area startup Earthgrid says it’s developing a plasma boring robot that can dig underground tunnels 100x faster and up to 98% cheaper than existing tech, and it plans to use it to start re-wiring America’s energy, internet and utilities grids. New Atlas reports: Most tunnels dug today are made by massive, mechanical rotary boring machines, which scratch cutting wheels against rock and evacuate the debris behind them, lining the tunnel walls as they go. It’s painstakingly slow, hugely expensive, and the cutting heads and drill bits often need changing or maintenance. But there’s another way to get through the toughest rock — as we outlined in our January article about Petra’s thermal drilling robot. Blasting rock with high temperatures can fracture and vaporize the stone in a process called spallation, and blasting this damaged rock with high pressures causes it to flake, chip and blow away.
You can do this without touching the rock walls at all, so the equipment can do entire tunnels without stopping if necessary. It can run entirely on electrical power, opening up the possibility of entirely emissions-free drilling, and both Petra and Earthgrid claim it’s much, much faster and cheaper than doing things mechanically รข” to the point where previously unfeasible projects can become economically viable. Earthgrid doesn’t seem to be as far along as Petra — indeed, it’s operating on pre-seed funding at the moment. But its intellectual property takes a spallation boring robot like Petra’s to the next level, placing multiple 27,000C (48,600F) plasma torches onto large discs held out in front of a “Rapid Burrowing Robot (RBR).” The torches are arranged in a Fibonacci spiral, starting from the center and widening out until they cover the full diameter of the bore.
Where Petra’s thermal drilling robot moves its head around to widen its hole, the RBR will fire on all torches at once, and rotate the torch-bearing discs to ensure full coverage, blasting the rock backward and collecting it into small pushcarts, each connected along the cable supplying electricity to the drill rig. That cable will need to handle some serious juice. In estimations submitted as part of a patent, Earthgrid founder Troy Helming describes a potential embodiment of the concept using 72 plasma torches to drill a 1-meter (3.3-ft) bore. In its low-power state, with each torch consuming 500 kW, Helming estimates a total power draw of 40 megawatts. If you need to get cracking, the high-power state would draw as much as a constant 120 MW. That’s for a hole you can barely crawl through; to triple the diameter and create a utility-sized tunnel you can comfortably walk through on a flat floor, you’d need to attach a larger “mother rig” behind the front rig. And if you wanted to move to a 10-m (33-ft) tunnel you could put a couple of lanes of traffic through, you’d need to attach another, even bigger “father rig” behind that. The total power draw in a “stage 3” system like this could get as high as 1.38 gigawatts — but that’s by no means the limit; upgrading the torches to higher power units would get the job done considerably faster, if an even more epic amount of electricity becomes available. How fast can Earthgrid tunnel? The company says it can bore up to 1 km (0.62 miles) per day, which it says is up to 100 times faster than existing borers. They also estimate a low-cost configuration could come in at as little as $300 per meter (3.3 ft) of tunnel.
“The company says it’ll either sell drilling as a service, or build, own, operate and maintain tunnels for customers looking for a long-term lease or toll arrangement,” adds New Atlas. “But it also hopes to put enough interlinking customer projects in place to create a subterranean network spanning the entire contiguous USA.”
Read more of this story at Slashdot.
Source: Slashdot – Earthgrid Aims To Rewire the USA Using Super-Cheap Tunnel Tech