My January 8th post illustrated a combination of carbon capture from coal-fired power plants with enhanced oil recovery from depleted oil fields using the recovered carbon dioxide. With a scheme like this, the considerable cost of extracting carbon dioxide from power plant flue gases is justified when the carbon dioxide is pumped to a nearby oil field for additional crude oil recovery(tertiary recovery) as the CO2 pushes out some of the remaining oil left in the ground from conventional drilling plus water flooding (secondary recovery).
C&EN’s September 1st issue details a first-of-its kind project as described above. NRG Energy Corp. and JXNippon Oil & Gas Exploration plan to divert about a third of the flue gases from NRG’s 610MW coal-fired power plant near Houston, Texas to a carbon dioxide scrubbing and recovery plant using an amine solvent system developed by Mitsubishi Heavy Industries. The carbon capture plant will cost $ 1 billion, financed jointly by the partners and by the Department of Energy, and will capture 1.6 million tons of CO2. This will be piped 80 miles to a relatively depleted oil field, where the current production of 500 barrels per day is expected to increase to 15,000 barrels per day which at $ 100/barrel would generate annual gross revenues of 540 million dollars.
The scrubbing technology was piloted by Mitsubishi at a pilot-scaled plant adjacent to a large coal-fired power plant near Mobile, Alabama.
Adding a carbon capture system (there are different kinds) to a coal-fired power plant is economically costly due to the so-called parasitic load of the capture system, which substantially decreases the efficiency of the power plant when the electricity generated is used to operate the capture system. In the case of the NRG/Nippon Oil plant, a separate 75MW natural gas-fired power plant will be built to run the capture system rather than decreasing the net electricity output of the coal-fired plant.
Since the economics of the proposed installation appear to make sense, we should see several other installations of this kind moving ahead. While some of the CO2 from tertiary recovery does escape to the atmosphere, this does not greatly detract from the fact that such combined systems can greatly decrease CO2 emissions, a stated goal of the Obama administration.