Friday, September 07, 2007
Convert Carbon Dioxide To Gasoline
The Center is promoting a process that would convert carbon dioxide into diesel fuel and gasoline, while producing hydrogen for fuel cell production.
We marry nuclear plants to coal plants that use pure oxygen combustion in the firebox to reduce the volume of stack gases. A scrubber would still be needed for sulfur dioxide, nitrogen oxides and mercury (Selective Catalytic Reducer). The nuclear plant (Pebble Bed Modular Reactor, Gen IV) is used to produce hydrogen via electrolysis (or high temperature electrolysis) or the sulfur-iodine cycle that will be piped away to produce fuel cells. The oxygen from the electrolysis process will be piped to the coal plant for use in the firebox. The hydrogen will also be mixed onsite with carbon dioxide from the coal plant stack in a water to gas shift to produce carbon monoxide, which will then be mixed with hydrogen using the gas to water shift in the Fischer-Tropsch process to produce a synthetic petroleum product (diesel fuel or gasoline). These processes need very high temperatures of about 900 degrees Celsius.
So carbon dioxide will be used from the coal plant to make a vehicle fuel while an adjacent nuclear plant will produce hydrogen for fuel cell production and oxygen for the coal plant firebox. The oxygen from the electrolysis will be used in the coal firebox to reduce the volume of emission gases by 80 percent, which represents nitrogen in the air. Excess carbon dioxide and CO2 from maintenance down times will be piped for sequestration. There will be little to no CO2 emitted from the coal plant because the gas will be used to make vehicle fuel. There will be CO2 released from vehicle use but these emissions would occur anyway from vehicle use.
We are still studying the energy penalties for these processes and the economics. If you have any input we would appreciate it. In the Fischer-Tropsch model pictured above the coal would be replaced with carbon dioxide. (Sources: Ken Schultz)