There is no shortage of work either. China recently completed a 20-kilometer railway tunnel in the Longmen Mountains after ten years of construction. There is the UK’s HS2 rail project, which will link London to cities in the north of the country and will have more than 100km of tunnels along the proposed route. And Peter Vesterbacka, who used to work for Angry Birds developer Rovio, is behind an ambitious plan to build an underwater tunnel between Finland and Estonia. These are just some examples.
Amberg predicts an increasing need for underground infrastructure for the future – not least to avoid the above-ground temperature increase caused by climate change. “It might not be such a bad thing to have a place where we have more consistent temperatures,” she says.
Tunnels are not just for transportation. Troy Helming, founder and CEO of San Francisco-based startup EarthGrid, emphasizes the need to bury power lines—that’s his company’s goal. The vast majority of transmission cables in the United States and Canada are above ground, he notes, exposing them to hurricanes and other storms and, increasingly, wildfires.
“Our plan is to provide North America with a supergrid,” he says, presenting a map with colored lines showing the grid from the east coast to the Pacific Ocean and future offshore wind farms to the west. It’s a plan that could help connect the fragmented US grid — and possibly even reach as far as Europe one day to tap into the vast offshore wind potential there. “It’s crazy and bold, and we know it,” says Helming.
One obstacle is the extremely tough rock, such as granite and quartzite, which makes traditional excavations difficult or impossible at some of these sites. As a solution, Helming relies on plasma torch technology that heats rock to around 6,000 degrees Celsius and blasts it into pieces. He suggests this could enable the creation of tunnels in hard rock 100 times faster than current technology. EarthGrid is developing a prototype robot with five plasma torches that Helming said should be ready for testing in March 2023. The Company also intends to complete its first small-scale commercial project by the end of this year.
Helming notes that in EarthGrid’s case, the tunnels aren’t circular in shape, but more of a traditional horseshoe shape — imagine a square with an arch at the top, rather than a flat ceiling. This makes it easier to install cable trays or, in larger traffic tunnels, a road surface on the level tunnel floor.
Competitor Petra also wants to use heat to drill through hard rock, but with a thermal cutter that uses a superheated fluid rather than a plasma torch. The idea is to cut through “nightmare geologies” with relative ease, says CEO and co-founder Kim Abrams.
“We just completed a 34-foot, 30-inch diameter granite tunnel last week,” she says, adding that the company hopes to start commercial work next year. And she mentions that the company is also working on a separate solution to address the other end of the spectrum — extremely soft or waterlogged soils often found under and near coastal cities.