Next Level Geothermal Power Generation (NGP) – A new sCO2-based geothermal concept

Abstract

Geothermal power generation with supercritical carbon dioxide (sCO2) has been object of numerous research studies over the past years. In comparison to conventional hydrothermal power plants, CO2-based geothermal systems exhibit several thermophysical, subsurface and power plant equipment, advantages. Essentially, a more effective geothermal heat extraction and less need for auxiliary pumping power, due to a much stronger thermosiphon effect, compared to water-based geothermal energy extraction can be highlighted. In this paper a thermodynamic evaluation of ‘Next Level Geothermal Power Generation’ (NGP) systems is provided. The impact of scaled geothermal cycles and of deviating geologic and ambient conditions, such as reservoir permeability, depth, temperature gradient and the cooling conditions, on both power output and costs is assessed. Furthermore, an improvement of the thermosiphon effect by an optimized cooling is demonstrated. Based on the thermodynamic simulations, capital costs and levelized costs of electricity (LCOE) are calculated and compared with other technologies. The results show that scaled NGP systems with optimized cooling can generate electricity at competitive LCOE.