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Experts are optimistic about the conversion of coal-fired power plants into clean geothermal energy production

Recording of the PIVOT 2022 session (screenshot)

How can we reuse old coal-fired power plants with the use of geothermal an inspirational session at the PIVOT 2022 Online Geothermal Conference as described in this guest post by Elizabeth Thomson for Quaise Energy.

In this excellent article shared by Quaise Energy correspondent Elizabeth Thomson, she shares details of a session on how coal-fired power plants could be repurposed to generate renewable energy by harnessing geothermal energy during the recent PIVOT 2022 online geothermal conference “All Hands on Deck”. focusing on .

As the world moves away from fossil fuels in the fight against climate change, could coal-fired power plants be repurposed to produce renewable geothermal energy? Panelists addressing the topic at PIVOT2022, a recent week-long geothermal conference, were excited about the potential, citing the number of enabling technologies that are coming online and the growing interest in heat beneath our feet.

After an extensive discussion that covered everything from the size of the potential market to a new drilling tool that could unlock the mother lode of geothermal energy, moderator Alex Fitzsimmons, senior director of ClearPath, brought the group back for the session “Conversion of coal-fired power plants to geothermal energy: on the horizon or science fiction?”

“A lot of technological progress [needed] enter this proof stage where you will have physical proof that they work. So I would say we’re ready to launch, if we can just bring together the right utility, the right contract and engineering expertise, and the right site to launch the evidence to show it can be done,” Ken said. Wisian, geothermal. geophysicist and associate director of the Bureau of Economic Geology at the University of Texas, Austin. “The situation could accelerate dramatically over the next few years. We just need the proof projects to land.

The Opportunity

Neeraj Nandurdikar is Senior Vice President at Wood Mackenzie, a global energy research and consulting firm. He started the session by outlining the potential opportunity, noting that there are around 4,200 coal-fired power plants around the world, of which around 1,000 appear to be retired. Most (some 2,200, with 2,000 in operation) are in China, which also has 84 plants under development.

The United States is next with about 750 factories, of which about 200 are in operation (no new projects are under construction). India, Indonesia and Germany round out the top five countries with the most coal-fired power plants. Many factories in the United States, he said, are idle or closed due to lack of economic incentive. “So from our perspective, the opportunity is great if something can be done with these assets.”

John Kosub is a senior manager at CPS Energy, a utility serving the San Antonio area. He made a similar point. CPS has made huge investments in equipment associated with coal-fired power generation, such as steam turbines and grid interconnection, “so there is a significant cost advantage to reusing those investments,” did he declare. Continue to use labor “would be [another] big advantage. »

Coal-fired plant conversions and new geothermal operations, or those built from scratch, could also “take advantage of the existing oil and gas workforce and pivot it completely towards this goal,” said Kevin Bonebrake. , CFO of Quaise Energy. Bonebrake noted that the majority of Quaise employees have an oil and gas background, including co-founder and CEO Carlos Araque. [Araque was among the winners of a PIVOT2022 Five on Fire award recognizing geothermal catalysts of the year.]

Where are we going to start?

Where are the most promising areas for a conversion from coal to geothermal energy?

“The hotter the better,” Wisian said. This means focusing first on coal-fired power plants near superhot rock relatively close to the Earth’s surface that can be found in places like the western United States, Iceland, and near volcanoes. .

For most of the world, however, such super hot rock is not accessible. It’s too low, ten to 20 kilometers (about 12 miles). Conventional drill bits used in the oil and gas industry cannot withstand the extreme temperatures and pressures at these depths.

Bonebrake explained how Quaise’s new drilling technology could change that “by allowing you to go deeper and hotter than anyone has been able to go before”.

This is important, he said, because water at these temperatures and pressures (greater than about 700 degrees F and 220 times atmospheric pressure) enters a supercritical phase, where it behaves like a super dense vapor. . Supercritical water, in turn, can carry 5 to 10 times more energy than regular hot water, making it an extremely efficient energy source. “When you think about taking that energy density and dividing it by the cost of developing a [geothermal] area, you see a sea change in the economy towards geothermal,” Bonebrake said.

Earlier, Wisian noted that “getting to the level of energy density of a coal-fired power plant is going to be tough for geothermal…unless you get to super deep, supercritical situations.”

To achieve these conditions, Quaise replaces conventional drill bits that mechanically break rock with millimeter wave energy (cousins ​​of the microwaves that many of us cook with). These millimeter waves literally melt and then vaporize the rock to create ever deeper holes. An inert gas that accompanies the millimeter waves brings the vaporized rock to the surface.

Bonebrake explained that a single module of the final system would consist of three deep wells: one that injects water, and two more to collect heated water and transport it to the surface. The heated water is then used to generate electricity in the power plant, after which it is recirculated back to the injection well to repeat the cycle.

Other catalysts

Wisian applauded the many developments in geothermal technology outlined at the conference, but stressed that “you can’t ignore geology. It’s like, no matter how good your new jet is, if you’re going somewhere, you need as detailed a weather forecast as possible for your landing site. Fortunately, “that old-fashioned geological detective work” is common to the oil and gas industry. “I’m interested in transitioning this methodology and mindset to…geothermal.”

An audience member asked if there is a need for a selection tool with technical, financial and regulatory aspects that can help utilities evaluate their options. “Yes,” said Wisian. “A publicly available or shareable modeling tool would be a significant step forward.”

Nandurdikar of Wood Mackenzie said such a tool is being developed by his company and Quaise. Among other things, they have already mapped all coal-fired power plants in the United States with an accurate assessment of each site’s geothermal attractiveness.

Fitzsimmons concluded the session noting that “finally geothermal is starting to get some of the attention it deserves. We just have to keep moving forward. »

All PIVOT2022 sessions have been recorded and are available on the web.

You can access the session on converting coal-fired power plants here.

Article by: Elizabeth Thomson, correspondent for Quaise Energy, [email protected]