European and US Efforts To Develop Geothermal Energy Are Headed in Different Directions

_ Writing about emerging geothermal technology requires dealing with the fact that it is emerging in different forms in different places. A common thread of what’s new are methods based on drilling wells into hot rock to deliver fluid into hot formations to harvest energy. Chances are that sentence is not exactly an accurate description of any particular method because of the significant differences among them. Some use hydraulic fracturing while others do not. One pumps water from well to well, another into the fractures of a single well, and the third keeps the fluid inside the wellbore. And the end product varies as well. In the US, the big early developments are aimed at generating electricity for the grid and storing energy in developments where wells are fractured. In Germany, the big target is providing hot water to district heating systems that deliver it to a wide range of customers in urban areas. New technology there must avoid fracturing. In Germany, they are testing a new geothermal method that harvests heat in deep well loops using a fluid that brings energy to the surface with minimal pumping. “In Utah or Nevada, the use case is they do electric only versus in Europe where it is more heat plus electricity,” said Florian Mueller, a PhD candidate doing research on geothermal at the Energy and Technology Policy Group in Zurich, Switzerland. In both cases these methods were developed by startups whose early commercial applications require adapting to a mind-numbing list of external factors. As a result, “Geothermal will look different everywhere,” said Ken Medlock, the senior director of the Center for Energy Studies at Rice University, during a panel session at this year’s Offshore Technology Conference (OTC). Adaptation The differences reflect a common challenge faced by innovators. A practical solution to a pressing problem, engineered to be reliable and cost-competitive, is just the starting point. Growth from there will depend on how they adapt to the market. In the US, Fervo Energy’s first large-scale commercial project in southern Utah is heating water by pumping it from injection wells to production wells through rock fractured from both sides. Produced water will need to be around 400°F—higher is better—to ensure it can be used to efficiently generate electricity for consumers in southern California. In southern Germany, Calgary-based Eavor Technologies is building a series of 12 flow loops with cased vertical wells linked by a long, uncased lateral that is treated to ensure the fluid remains in the wellbore and is heated efficiently. When built, each loop will be filled with a fluid formulated to conduct geothermal energy to the surface where it will be used for home heating during the cold months, and electric generation during warmer ones. The differences often reflect the vagaries of regulation. Fervo is building its 400 MW geothermal electric plant, Cape Station, 500 miles from its initial customers at a site in southern Utah where the quality of the formation was already known because it adjoins the US geothermal test site commonly known as FORGE. Also, the remote desert site minimizes the likelihood of opposition to drilling and fracturing, which is not the case in California which has banned fracturing.

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