A towering wall of white granite stood before a small team of engineers at a California quarry. The extremely hard, impermeable rock was about to face a new type of tunnel-boring technology.
EarthGrid’s rock-melting tunnel-boring machine (TBR) then roared into operation.
“It’s like lighting a rocket,” says Troy Helming, founder and CEO of EarthGrid, describing the dramatic startup sequence for the three plasma torches mounted at the front of the machine.
The rotating torch heads produce superheated plasma streams reaching temperatures of up to 27,000 degrees Celsius—far hotter than the surface of the Sun. After ignition, the torches quickly become quiet as the machine begins cutting through the rock.
During a California test in January, EarthGrid’s cigar-shaped tunnel-boring machine cut through 3 meters of solid granite. Helming says the system creates a powerful vortex inside the tunnel, allowing it to remove debris that can sometimes resemble molten lava.
“I actually got a little emotional watching it,” the entrepreneur said. “I’ve been waiting for this moment for 10 years.”
Advanced technologies such as EarthGrid’s plasma tunnel-boring machine could make underground construction faster, more efficient and more affordable. Moving power cables, communications networks, substations, data centers and other critical infrastructure underground can improve security, but traditional tunneling has typically been expensive and technically challenging.
Engineering companies told BBC News that demand for underground infrastructure is growing. The war in Russia and Ukraine has also highlighted the vulnerability of above-ground facilities to drone attacks, increasing interest in protected underground systems.
Helming said companies have expressed interest in using EarthGrid’s tunnel-boring machines to install power lines, fiber-optic cables and pipelines for transporting water, natural gas and ammonia.
EarthGrid is also exploring tunnels for underground cargo transportation near airports and warehouses. Such systems could help reduce road congestion and take more delivery trucks off the streets, Helming said.
Although the January TBR test was successful, Helming said the machine slightly overbored the upper and left sections of the tunnel. Engineers plan to address the issue by adjusting the system so its internal vortices alternate direction approximately every five minutes. The company hopes to deploy its plasma-powered tunnel-boring machine commercially next year.
Source: www.bbc.co.uk