The next generation of geothermal energy technology — called enhanced or engineered geothermal, or EGS for short — has long been just out of reach in a commercial sense. It’s been too expensive, mostly due to the high cost of drilling new enhanced geothermal wells into hard, hot rocks more than 10,000 feet below the earth’s surface.
According to next-gen geothermal startup AltaRock, though, a new type of drilling technology could help solve the problem of expensive drilling. AltaRock CEO Aaron Mandell told me that the company has entered into a partnership and created a joint venture with a company called On Energy, which is the U.S. supplier of Korean drilling company Hanjin D&B. AltaRock and On Energy plan to use a new type of “hammer” drilling tech that could help commercialize enhanced geothermal energy.
The new tech is called a “water hammer” drilling machine, and it pulverizes rock by rapidly hammering down on the rock surface with brute force and creating huge vibrations. This is different than the more commonly used drilling that employs a rotary bit (rotating cones) to grind down rock. When it comes to hard rock surfaces, rotary drilling can be really slow, the bit wears out quickly and needs to be replaced, and it’s been difficult to achieve the depths of more than 10,000 feet that EGS needs. AltaRock has faced iproblems with drilling through hard rocks at its sites in the past.
Hammer drilling, by contrast, can more quickly and more economically achieve these deep drilling depths. The problem with hammer drilling in the past, though, has been that companies have mostly used air to deliver pressure to the bits. That has required extremely large air compressors and pushed up the price of hammer drilling.
Hanjin D&B’s water hammer drill uses water (hence the name) to deliver pressure to the drill bit, and the companies say this innovation means the water hammer drill can deliver wells of more than 12,000 feet, at ten times the speed of conventional drilling, and up to 50 percent of the cost. This video shows the water hammer drill in action.
We’ll have to wait and see if the water hammer can provide enough of a savings breakthrough to help AltaRock’s next-gen geothermal tech take off. In the past, many companies claimed drilling breakthroughs that turned out to be largely incremental. AltaRock’s Mandell told me that the company will be using the water hammer drill at its own site at the Newberry Volcano in Oregon. It could be one of the only new (“greenfield”) commercial EGS sites in the world.
It’s been a long, hard road for AltaRock over the past seven years. Founded in 2007 during the wave of excitement around EGS, the company was funded by Khosla Ventures, Google.org, Advanced Technology Ventures, Kleiner Perkins and Paul Allen’s Vulcan Capital.
AltaRock was able to build a demonstration project at Newberry, funded by $21.4 million from the DOE’s stimulus program, and a year ago the company showed it had created multiple, stimulated geothermal zones from the single drilled well at Newberry. That was a proof of concept that rock permeability can be controlled and “engineered” using stimulations. But the next step at Newberry has been to find more financing to drill another well at the site and get the power plant up and running.
In the meantime, AltaRock has started to concentrate on using its EGS tech to improve, or stimulate, under-performing older geothermal wells. Traditional geothermal power plants tap into the somewhat rare earthly occurrence of hot underground rocks meeting significant water or steam, which can be pushed to the surface and then recirculated to keep a plant running.
These older wells commonly lose energy capacity over the years, and operators have traditionally done things like injecting waste water into sites to boost capacity. AltaRock uses other more technologically advanced techniques to boost capacity of older wells. For example, it injects them with particles of a material that can temporarily plug parts of the well and enable many more tiny cracks to form within the reservoir.
It took a long time for AltaRock to get to where it is today, but the company is nothing if not innovative. In a year that a new type of financing structure for solar, called solar yieldcos, became popular, AltaRock decided to launch its own version of the yieldco for geothermal. And when the company faced issues with communities around earthquakes, and slow drilling at new sites, the team routed around those challenges, too.
The large geothermal companies don’t really take EGS that seriously at this point — it’s a small, nascent market — so AltaRock continues to write the playbook on new technologies, new partnerships and new financing models that could one day make EGS a reality.