Petra (San Francisco, California, USA), described as the first robotics company capable of undergrounding critical utilities through hard geologies, recently announced the successful completion of a 20-ft (6.1-m) demonstration tunnel through the hardest rock on earth. Series A funding was led by DCVC (Palo Alto, California, USA), a leading deep tech venture firm.
As part of this project, Petra has invented a new hard rock-boring robot, transforming the way all utilities are buried underground by tackling the hardest problem in underground construction: how to bore utility tunnels reliably and cost effectively through nightmare geologies.
According to the company, the ability to underground utilities is essential to help meet the increasing global demand for energy and to avoid grid-related disasters due to climate change.
“In the past, there have only been a handful of costly and inefficient methods for tunnel construction, starting with manual tools and evolving to the modern tunnel-boring machine,” says Kim Abrams, CEO and co-founder of Petra. “Our non-contact method is the next evolution of tunneling and will usher in a new age of underground utilities.”
Based on those needs, Petra worked to develop the first non-contact, thermal-drilling method that can uniquely bore 60-in (152.4-cm) diameter micro tunnels through hard rock, making it possible to bore utility tunnels through previously impenetrable geologies.
Conventional micro-tunneling machines are purpose built to a single diameter, according to the company. But Petra says it is now capable of boring a range of diameters between 20 and 60 in (50.8 and 152.4 cm), which can dramatically reduce the cost of tunneling.
Petra also offers the first reverse-tunneling technology, which it says can facilitate easier machine maintenance and cutter head rescue. Through this process, the company is enabling customers to rapidly bury critical utilities for a fraction of the cost of legacy techniques, which includes construction services, tunnel development, and ongoing maintenance.
“At DCVC, we’re committed to investing in companies that are building solutions to make our society’s infrastructure more resilient,” says Chris Boshuizen, a partner at DCVC. “Petra’s tunneling technology is providing a safer, faster, and more cost-effective option for all underground infrastructure, electricity, water, sewage, and enables projects the world would never have been able to do before.”
According to Petra, this semi-autonomous robot can tunnel faster and cheaper than conventional undergrounding methods, and through geologies previously thought impenetrable. By contrast, traditional micro-tunnel boring machines (MTBM), horizontal directional drilling (HDD), and other conventional “trenchless” methods have cutter heads that easily break when drilling through hard rock, increasing project cost and complexity.
“Petra successfully completed a 20-foot bore through hard Sioux Quartzite, where we averaged an astounding one-inch-per-minute in a geology usually excavated by dynamite,” says Petra CTO Ian Wright. “No undergrounding method has been able to tunnel through this kind of bedrock until now. This achievement is due to Petra’s thermal drilling method, which efficiently bores through rock without touching it.”
Source: Petra, https://petra.cc.
Editor’s note: This article is reprinted with permission from the Material Matters section of the June 2022 print issue of Materials Performance (MP).