What Makes ECO2G™ Better?
Lack of subsurface permeability has been the greatest constraint for conventional hydrothermal projects. Conventional geothermal is limited to moderate temperature zones where there is sufficient permeability for water to flow to production wells and so is limited to only about 2% of the available geothermal resource. An experimental technology, water-based “Enhanced Geothermal Systems” (EGS), has tried for decades to create artificial permeability. However, water-based EGS is still far from commercialization because of the difficulty of creating long symmetrical cracks in the complex and varied terrains of the “brittle zone.”
ECO2G represents a radically different approach to EGS. To circumvent the permeability problem, ECO2G circulates supercritical CO2 (sCO2) in a closed-loop pipe system to gather and transfer high temperature heat. ECO2G substantially reduces drilling risk, another obstacle to project development. Conventional hydrothermal projects drilling into an area with the right combination of heat, water and permeability. Consequently, about half of all drilled wells fail to produce commercial scale power. In contrast, ECO2G’s optimized closed-loop design only requires finding sufficient heat, a much easier task.
Using sCO2 instead of water confers three important advantages. First, it eliminates the need for large amounts of water. Second, sCO2 expands when heated, which enables the thermosiphon to push the CO2 around the system, thereby avoiding a parasitic power loss of up to 30% as in some hydro projects. Third, the properties of sCO2 are making possible the development of small but very efficient sCO2 turbines.
Lack of subsurface permeability has been the greatest constraint for conventional hydrothermal projects. Conventional geothermal is limited to moderate temperature zones where there is sufficient permeability for water to flow to production wells and so is limited to only about 2% of the available geothermal resource. An experimental technology, water-based “Enhanced Geothermal Systems” (EGS), has tried for decades to create artificial permeability. However, water-based EGS is still far from commercialization because of the difficulty of creating long symmetrical cracks in the complex and varied terrains of the “brittle zone.”
ECO2G represents a radically different approach to EGS. To circumvent the permeability problem, ECO2G circulates supercritical CO2 (sCO2) in a closed-loop pipe system to gather and transfer high temperature heat. ECO2G substantially reduces drilling risk, another obstacle to project development. Conventional hydrothermal projects drilling into an area with the right combination of heat, water and permeability. Consequently, about half of all drilled wells fail to produce commercial scale power. In contrast, ECO2G’s optimized closed-loop design only requires finding sufficient heat, a much easier task.
Using sCO2 instead of water confers three important advantages. First, it eliminates the need for large amounts of water. Second, sCO2 expands when heated, which enables the thermosiphon to push the CO2 around the system, thereby avoiding a parasitic power loss of up to 30% as in some hydro projects. Third, the properties of sCO2 are making possible the development of small but very efficient sCO2 turbines.
