- Petra, a San Francisco-based robotics company focused on installing utilities underground, has developed a boring robot designed to tunnel utility channels through difficult terrain, including bedrock. The robot's thermal spallation drilling process creates "micro tunnels" between 20 and 60 inches in diameter by bombarding the rock with high-energy particles, removing material without making direct contact.
- This technology enables Petra to bury utilities deep below the surface and in difficult terrain, expanding the reach of the utility grid and providing greater resilience against climate-related disasters, the company said in a press release.
- Last month, the firm announced that it had completed a 20-foot demonstration bore through Sioux quartzite bedrock in a quarry in southern Minnesota, averaging 1 inch per minute.
The Energy Information Association estimates that the global demand for energy infrastructure will increase by 50% over the next 30 years. At the same time, the global effects of climate change highlight the vulnerabilities present in current utility installations, including above-ground power lines and underground utilities in soft soil layers.
Petra anticipates that installing utilities further underground will create a more resilient grid and reduce the risk of man-made disasters, such as wildfires or explosions.
"As the former President of SoCal Edison, I oversaw capital projects in urban, suburban and rural mountainous areas. A robot that can bury utility facilities in bedrock would have been a game-changer for us," said Petra advisor Bob Foster. "In cities, it would allow us to bury utilities in bedrock, below the existing infrastructure. In mountainous areas, like the Sierra foothills, it would allow us to bury utilities in the most fire-prone regions of our state."
Modern "trenchless" tunnel-boring machines — including micro tunnel boring machines and horizontal directional drilling — incorporate cutter heads that break easily when tunneling through hard rock, according to Petra's press release. Petra's thermal spallation drilling method aims to remove this obstacle and reduce the costs and complexity associated with utility boring projects.
In addition to its standard bore, Petra's boring robot is also capable of reverse-tunneling, enabling both machine maintenance and cutter head rescue.
Petra raised $33 million in its Series A funding round last month, led by venture capital firm DCVC with ACME Capital, Congruent Ventures, 8VC, Real Ventures, Elementum Ventures and Mac Venture Capital.
New boring methods and technologies have garnered recent attention on a larger scale with Elon Musk's Boring Co. underground transit projects, currently in various stages of planning and operation across the country. The Boring Co.'s Prufrock drill creates tunnels at a standard 12-foot width or a 21-foot width for freight transportation, and currently drills at a speed greater than one mile per week, according to the company.
This article has been updated with new imagery, as well as the location of Petra's boring robot demonstration.