There is considerable work being done to develop a supercritical carbon dioxide closed-cycle gas turbine to operate at temperatures near 550 °C. This is a significant usage, which could have large implications for bulk thermal and nuclear generation of electricity, because the supercritical properties of carbon dioxide at above 500 °C and 20 MPa enable very high thermal efficiencies, approaching 45 percent. This could increase the electrical power produced per unit of fuel required by 40 percent or more. Given the volume of polluting fuels used in producing electricity, the environmental impact of cycle efficiency increases would be significant.[10]
Supercritical carbon dioxide is also an important emerging natural refrigerant, being used in new, low carbon solutions for domestic heat pumps.[11] These systems are undergoing continuous development with supercritical carbon dioxide heat pumps already being successfully marketed in Asia. The EcoCute systems from Japan, developed by Mayekawa, develop high temperature domestic water with small inputs of electric power by moving heat into the system from their surroundings. Their success makes a future use in other world regions possible.[12]
Supercritical carbon dioxide has been used for more than thirty years to enhance oil recovery in mature oil fields. At the same time, there is the possibility of using the various "clean coal" technologies which are emerging to combine such enhanced recovery methods with carbon sequestration efforts. Using gasifiers instead of conventional furnaces, coal and water is reduced to hydrogen gas, carbon dioxide, and ash. This hydrogen gas can be used to produce electrical power in combined cycle gas turbines, while the CO2 is captured, compressed to the supercritical state, and injected into geological storage, possibly into existing oil fields to improve yields. The unique properties of supercritical CO2 ensure that it will remain out of the atmosphere.[13][14][15]
It has been suggested that supercritical carbon dioxide could be used as a working fluid in enhanced geothermal systems. Possible advantages compared to water include higher energy yield resulting from its lower viscosity, better chemical interaction, CO2 storage through fluid loss and higher temperature limit. As of 2011, the concept has never been tested in the field.
There is considerable work being done to develop a supercritical carbon dioxide closed-cycle gas turbine to operate at temperatures near 550 °C. This is a significant usage, which could have large implications for bulk thermal and nuclear generation of electricity, because the supercritical properties of carbon dioxide at above 500 °C and 20 MPa enable very high thermal efficiencies, approaching 45 percent. This could increase the electrical power produced per unit of fuel required by 40 percent or more. Given the volume of polluting fuels used in producing electricity, the environmental impact of cycle efficiency increases would be significant.[10]
Supercritical carbon dioxide is also an important emerging natural refrigerant, being used in new, low carbon solutions for domestic heat pumps.[11] These systems are undergoing continuous development with supercritical carbon dioxide heat pumps already being successfully marketed in Asia. The EcoCute systems from Japan, developed by Mayekawa, develop high temperature domestic water with small inputs of electric power by moving heat into the system from their surroundings. Their success makes a future use in other world regions possible.[12]
Supercritical carbon dioxide has been used for more than thirty years to enhance oil recovery in mature oil fields. At the same time, there is the possibility of using the various "clean coal" technologies which are emerging to combine such enhanced recovery methods with carbon sequestration efforts. Using gasifiers instead of conventional furnaces, coal and water is reduced to hydrogen gas, carbon dioxide, and ash. This hydrogen gas can be used to produce electrical power in combined cycle gas turbines, while the CO2 is captured, compressed to the supercritical state, and injected into geological storage, possibly into existing oil fields to improve yields. The unique properties of supercritical CO2 ensure that it will remain out of the atmosphere.[13][14][15]
It has been suggested that supercritical carbon dioxide could be used as a working fluid in enhanced geothermal systems. Possible advantages compared to water include higher energy yield resulting from its lower viscosity, better chemical interaction, CO2 storage through fluid loss and higher temperature limit. As of 2011, the concept has never been tested in the field.
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