14 Mar 2023

Polpis Systems Publishes Open Proposal for Supercritical-CO2 Geothermal

14 Mar 2023  by thinkgeoenergy   

Sandia National Laboratories, Albuquerque, NM, U.S. (source: flickr/ NNSANews, creative commons)
Polpis Systems has published an open proposal for a geothermal power generation system that uses supercritical CO2 (sCO2) as the working fluid. The proposal aims to provide an option for the practical implementation of supercritical geothermal power that overcomes the current cost and efficiency limitations of enhanced geothermal systems (EGS).

With this open proposal, Polpis Systems is soliciting interest from any person or agency wishing to getting involved or participate in any way. Interested participants may get in touch with Polpis Systems CEO Aaron Mandell ([email protected]).

The project will utilize a gravity-induced hydraulic fracture to circumvent the high cost of geothermal drilling, EGS efficiency challenges associated with conventional hydrofracturing and limited heat flow of closed-loop systems. A large, downward fracture will be propagated from a wellbore into a deep production zone to stimulate thermal convection to a shallower region using supercritical CO2 (sCO2).

The deep vertical fracture will be initiated using a high-density slurry containing an engineered conductive proppant to enhance thermal conduction from the rock surface to a high-enthalpy reservoir fluid. Power will be generated using a sCO2 turbine-generator (Brayton Cycle) at elevated efficiency, with the aim of demonstrating practical power densities of up to 100 MWe from a single geothermal well.

The project is also being supported by the Sandia National Laboratories. Sandia has been involved in developing sCO2 Brayton cycles for over 15 years and has experience in both computational modeling of cycles as well as experimental operation of functioning sCO2 systems. We had previously reported on the work of Sandia in exploring the use of explosions or propellants to predictably generate fracture networks in EGS sites.


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