What Earth Properties and Engineering Decisions Most Influence the Productivity of an Enhanced Geothermal System?. (February 2019)

• Record Type: Journal Article
• Authors: Pollack, Ahinoam; Mukerji, Tapan
• Is Part Of: Energy procedia. Volume 158(2019)
• Page Start: 6024
• Page End: 6029
• Publication Date: 2019-02
• Subjects: Enhanced geothermal system -- sensitivity analysis -- hydraulic fracturing; Power resources -- Congresses; Power resources -- Periodicals; Power resources; Conference proceedings; Periodicals; 333.7905
• DOI: 10.1016/j.egypro.2019.01.516
• Languages: English
• ISSNs: 1876-6102

Abstract

Abstract: It has been estimated that Enhanced Geothermal Systems (EGS) could supply 100 GWe (10%) of total electric capacity in the U.S [1]. An EGS artificially creates a geothermal system by stimulating an impermeable hot rock, injecting cold water into the hot reservoir, and extracting the heated water to generate electricity. This paper explores what earth properties and engineering decisions most influence the productivity of an EGS and therefore should be the focus of research and data acquisition. Using Monte Carlo simulation, 106 EGS models were generated varying the engineering decisions and uncertain earth parameters within ranges reported for a California site. Uniquely, the model accounts for the variability in stimulated hydraulic fractures. The models' hydro-thermal flow and energy production was then simulated, showing a wide range of power generation values from a P10 of 1.8 MW to a P90 of 7.3 MW. The production values were used in a distance-based sensitivity analysis to determine the factors governing EGS productivity. The parameters found to most influence productivity were the mean fracture length, spatial extent of the high temperature zone and rock permeability. These findings highlight the importance of further researching hydraulic fracturing in crystalline rocks and investing in proper characterization and choice of a site with high temperature and permeability.