Hate the Coal – But Love the Workers and Assets? Re-energize Coal Plants with Hot Rocks!

By Steve Klein
Klein Tech Advisors Group

No, I am not talking about Mick Jagger and the Rolling Stones’ monumental and enduring compilation album titled “Hot Rocks,” but rather the real, sizzling-hot rocks deep beneath all our feet that can be used to replace coal-fired power with renewable geothermal energy, while reusing valuable infrastructure and employees at existing coal plants.

Multiple economic, social and regulatory trends are forcing the shutdown of coal plants, which brings a cheer from most everyone, not just environmental activists. But while the environment will reap a benefit, the usual approaches for replacing the lost power—such as simply repowering the plant with natural gas or replacing the output with a new generating resource elsewhere—have their own set of negative consequences that are difficult to avoid.

Consider, for example, the Navajo Generating Station near Page, Arizona, on the Navajo Nation. It currently generates tens of millions of dollars in annual taxes and royalties to the Navajo Tribe and provides much-needed jobs in an area where unemployment often exceeds 50 percent. Shutting down and demolishing this coal plant will clean up the air but will also have detrimental economic and social effects on the tribe and the broader community.

Natural gas will play a role in transitioning away from coal but potential over-reliance on another fossil fuel can lead to other problems. Besides the continued carbon contribution, there are limits to the transportation and storage capacity of the nation’s gas system, and once that capacity is exhausted the price and availability to consumers will change significantly. Let’s face it, relying too heavily on natural gas for base-load power is a risk associated with the decline in the number of coal-fired power plants.

There are many other examples, including several in the greater Northwest–Centralia, Colstrip, Boardman, and Valmy–where existing coal plants are likely to be shut down in the near future or continue to be on the chopping block due to their carbon-heavy impact on climate change. These plants contribute to the economic vitality of their neighboring communities, and represent an infrastructure asset that ratepayers like you and me have invested in over the years. In a world where we like to focus on sustainable local community sourcing and reuse, you would hope there would be a solution that could retain local jobs and reuse the infrastructure that already exists.

There is a solution that sounds too good to be true and can work virtually anywhere a coal plant is located. It is clean and renewable, economic, safe and reliable, and allows the reuse of valuable infrastructure and employees at existing coal plants. That solution is replacing the heat produced from burning coal with heat emanating from hot rocks deep beneath the Earth's surface by developing an engineered geothermal system, or EGS.

EGS should not be confused with the relatively small number of conventional geothermal plants built at a limited number of naturally occurring unique sites that are often near thermal features such as hot springs or geysers. These locations have hot water close enough to the surface to allow the economic production of electricity or direct use for heating.

Instead, an engineered geothermal system mimics nature and can be created almost anywhere by enhancing pre-existing fracture networks in deep hot rocks and circulating water in them. After the introduced water is heated, it is drawn back to the surface, where the heat is extracted to generate power. It can be a closed loop system that uses the water source that cooled the coal plant. It can also use the wastewater produced from years of operating the coal plant that is collecting in surface ponds. And unlike intermittent renewables such as wind and solar, EGS power plants can function as baseload resources that produce power 24 hours a day, and can also have some ability to ramp their output to match peak demands.

There are several EGS plants successfully operating in other parts of the world but none in the United States. Work is underway to change that and bring that technology home. Interestingly, AltaRock Energy, a leader in providing advanced geothermal energy technology and services, was formed and located in Seattle, Washington, in 2007 with funding from clean technology investors such as Khosla Ventures, Kleiner Perkins, Google, Vulcan Capital and Advanced Technology Ventures, along with grant funding from the Department of Energy.

AltaRock is led by Susan Petty, who was part of the seminal study on the future of geothermal energy performed by the Massachusetts Institute of Technology in 2007. That study found that the thermal energy available in the hot rocks below the U.S. is nearly 140,000 times greater than the country’s entire energy consumption.

In 2013, AltaRock did a study for the Electric Power Research Institute (EPRI) on the use of EGS to both manage waste water and generate clean power at coal plants such as Colstrip. Colstrip is located in Montana but produces power that serves the entire Northwest, including the Puget Sound area. This study showed that EGS co-located with coal takes advantage of existing infrastructure and workforce, produces zero emissions, can use waste water to transfer heat from the hot rocks, and–importantly–be cost competitive.

Recently, Ms. Petty founded Hotrock Energy Research Organization (HERO), a 501c3 nonprofit to continue research and development in geothermal technology. Its aims include advancing education and outreach about EGS, and performing feasibility studies and pilot projects demonstrating that the technology can be used to generate geothermal power anywhere, including at existing coal plants.

When you think about solutions to our energy challenges in the United States, it is likely to be a combination of approaches and technologies rather than a single silver bullet. EGS is a solution that deserves more consideration and attention. For example, a recent bill introduced into the Washington State Legislature to encourage conversion of the state’s lone coal plant in Centralia listed natural gas and biomass as the only qualifying alternatives.

This EGS solution has not been well-known, understood or appreciated, but as we face the environmental, economic, operational and social consequences of closing coal plants, EGS should come to the forefront of the discussion of alternatives. Please join me in raising awareness of this alternative with legislators, regulators, media, Bill Gates and other influential technology advocates, and the public in general. Let’s ensure that EGS is on the table with other viable options, where its value can be comparatively measured and factored into our decision-making, rather than ignored.

Note: Steve Klein is a retired Electric Utility Executive who is a recognized leader in the research and development of clean energy technologies and is currently a Principal with Klein Tech Advisors Group. Mr. Klein is also Chairman of the Board of the CleanTech Alliance and a Board Member of the nonprofit Hotrock Energy Research Organization (HERO).