Hybrid Low-Grade Geothermal-Biomass Systems for Direct-Use and Co-Generation: from Campus Demonstration to Nationwide Energy Player

Abstract

The Climate Action Plan (CAP) at Cornell University in Ithaca, New York, USA proposes a set of actions to achieve a carbon-neutral campus by 2050 or sooner. These actions include energy conservation initiatives, upgrading the campus heat distribution system, as well as developing renewable and sustainable heat and electricity production from geothermal, biomass, wind, and solar resources at a scale to serve its campus of over 30,000 students, faculty and staff. The CAP envisions a hybrid co-generation system using an Enhanced Geothermal System (EGS) and biomass that could supply nearly 100% of the campus heating demand, a small fraction of the electricity demand, and cuts CO2 emissions by more than 40%. In this paper, the GEOPHIRES software was used to simulate a low-grade EGS site in Ithaca, although still with geothermal gradients above average for the Northeast, and was applied in combination with published regional data on biomass cultivation and gasification to explore the technical and economic potential of a hybridized geothermal-biomass system. With base case assumptions without any subsidies or incentives, an initial capital investment of $217M resulted in a levelized cost of heat (LCOH) of 15.9 $/MMBtu (5.4 ¢/kWh). This system would provide 98% of the campus heating demand, 7% of the electricity demand, and would cut CO2 emissions by 94,000 metric tons (43%). Further, with the Cornell campus geothermal-biomass system serving as a community-scale demonstration plant, the potential of hybrid geothermal-biomass systems as major energy suppliers for heat and electricity on a regional and nationwide scale is considered in this study.