Transitioning Coal to Geothermal

Abstract

More than 50,000 MW of aging coal fired power generation capacity will need to be either repowered or retired between now and 2030, much of it in the next 10 years. These plants can’t meet today’s emission standards or the new standards of the Clean Power Plan even with prohibitively expensive pollution control equipment. While low prices drive many of these plants to consider natural gas repowering as the solution to their continued operation, renewable portfolio standards and the lack of sufficient gas supply pipeline capacity prevents most from taking this option. Wind and solar can offset some of this power supply, but coal plants by their nature provide baseload power. Conventional geothermal energy is limited to places where we can find it. Only with EGS can we replace coal with geothermal in a wide variety of locations. Co-locating the geothermal project on land owned by the coal plant takes advantage of the grid connection, permitting and cooling system as well as a skilled workforce. Waste water stored in ponds at the site can be used for reservoir fill up. Costs remain the major issue for utility scale EGS power generation. EGS plants running in Europe have relied on feed-in-tariffs only available for small scale projects. We are studying the impact of scaling, learning-by doing and technology improvement on the LCOE for utility scale EGS power production. Other technologies such as wind and solar have seen very large decreases in LCOE and installed cost as more and larger facilities have been installed. Photovoltaic power in particular has seen a dramatic decrease in cost as more and more solar facilities have come on line. The question is: Can EGS see the same kind of cost decreases and what is needed to realize the goal of replace coal with geothermal?