What Are the Challenges in Developing Enhanced Geothermal Systems (EGS)? Observations from 64 EGS Sites

Abstract

Since the 1970s, numerous projects have experimented with methods to enhance permeability at both existing and new geothermal sites. While the accomplishments and findings of these Enhanced Geothermal Systems (EGS) are at the center of publications on these sites, there is less discourse on what has gone wrong. Understanding the obstacles facing EGS projects can help EGS developers avoid potential mistakes in the future and focus research efforts on the most prevalent development issues. This paper compiles and describes challenges experienced in EGS projects, based on observations from 64 EGS sites. We found that six sites ceased operations temporarily or shut down due to seismicity or seismicity concerns. Drilling and plant operation issues, such as holes and cracks in wellbore casing, stuck drill strings, and well collapses, have increased costs, delayed or terminated at least 24 EGS projects. At least 18 sites faced challenges in reservoir creation and circulation, such as insufficient connectivity between the injection and production wells or water loss. Inability to raise financing either initially or in later project phases has been a major block for many EGS projects. While EGS sites often encounter difficulties, this review shows that at least 29 of the projects, including in-field and green field, continue to operate and generate electricity at an increased rate due to stimulation operations.