Toward affordable low-carbon power: Economic and environmental analyses of integrating CO₂-EGS with IGCC

We are currently studying the economics of Enhanced Geothermal Systems (EGS) and various factors that can reduce its Levelized Cost of Electricity (LCOE). As part of this effort, we are exploring the potential of reducing the collective system's LCOE by integrating EGS with Integrated Gasification Combined Cycle with Carbon Capture and Sequestration (IGCC-CCS). CO ₂-EGS offers a number of potential benefits. For example, heat transfer and fluid dynamics simulations suggest that CO₂ could be a better heat mining agent than water in EGS. Additionally lower viscosity and larger expansivity of CO₂ in comparison to those of water are expected to reduce parasitic losses by increasing buoyancy forces. CO ₂ sequestration would be an ancillary benefit. Similarly, IGCC has a number of benefits. The chemical conversion of coal to synthetic gas is a cleaner process than coal combustion. IGCC plants operate at higher efficiencies and produce a pure stream of CO₂ which can be directly used in EGS as a heat extraction fluid. Given these benefits and complementarity, we are studying the economics, environmental footprint, and operational envelope of an integrated CO₂-EGS-IGCC system. This paper describes our preliminary results including estimates of LCOE, environmental footprint, and issues associated with the operating envelope.