Carbon dioxide-enhanced geothermal systems for heat and electricity production: Energy and economic analyses for central Poland

Abstract

The pursuit of economically feasible and socially acceptable carbon capture technologies is often focused on the permanent storage of carbon dioxide (CO2). Among well-established CO2 capture, utilisation, and storage technologies such as enhanced oil recovery, some have recently gained interest for application in the energy sector. One such technology is the use of CO2 as a working fluid in enhanced geothermal systems. The potential benefits of this technology will strongly depend on the parameters of the geological reservoir. The use of supercritical CO2 as a working fluid can provide additional benefits because of the occurrence of partial sequestration of CO2. The main goal of this study is to investigate which of the geological and wellbore parameters of an enhanced geothermal system have the most significant impact on the energy and economic performances of the investigated power generation systems. This paper presents the results of energy assessment of the analysed power generation systems together with the economic effects of their operation. The presented results suggest that CO2-enhanced geothermal systems can be a feasible candidate for the utilisation of the captured CO2 and can simultaneously be a valid source of heat and/or electricity. The analysed process configurations prove that the optimal design of the surface part of the CO2-enhanced geothermal system strongly depends on the parameters of the geological reservoir as well as on the availability of heat sinks (e.g. a low-temperature district heating system), and that this design provides a payback time of 10–12 years in the most optimistic scenario. The analysed enhanced geothermal systems, when compared with conventional geothermal energy systems, are characterised by a higher cost of electricity generation (average-weighted levelized cost of electricity of about 110–170 EUR/MWh as compared with 60 EUR/MWh for conventional systems), mainly because of the significantly higher (1.5 times) total installation costs of the former.