Clean Coal Power Initiative (CCPI) -
Recovery Act: W.A. Parish Post-Combustion CO2 Capture and Sequestration Project
Project No: FE0003311
The U.S. Department of Energy is providing financial assistance to NRG Energy (NRG) to demonstrate the addition of a commercial-scale post-combustion carbon capture technology on its existing coal-fired W.A. Parish Generating Station (PGS) located in Thompsons, Texas, southwest of Houston, Texas. The project will demonstrate the ability of an advanced amine-based CO2 capture system to capture 90 percent of the CO2 emitted from a flue gas slipstream equivalent to 240 Megawatts (MWe) in size. The host power generation unit will not be derated because the power and thermal energy required to operate the CO2 capture and compression system will be provided by a cogeneration plant comprised of a combustion turbine with a heat recovery boiler. These advances are anticipated to reduce carbon capture costs and increase system flexibility and efficiency.
The captured CO2 will be compressed and transported through an 80 mile pipeline to an operating oil field where it will be utilized for enhanced oil recovery (EOR) and ultimately sequestered. The scale of the project has been increased because the original 60 MWe project was determined to be too small to immediately induce significant oil production. The project scale-up is currently in development and will require additional capital from the recipient.
A portion of the flue gas from W.A. Parish Unit 8 that has already been treated to reduce nitrogen oxides (NOx), particulate matter, and sulfur dioxide (SO2) will be diverted from the existing stack to the CO2 capture system. When entering the CO2 capture system, the flue gas is first routed to the flue gas cooler for conditioning, i.e., cooling, dehydration, and additional SO2 removal. The flue gas is cooled because the absorption of CO2 is favored at lower temperatures. The cooled flue gas will contact a circulating sodium hydroxide (NaOH) solution for polishing SO2 removal, where 98 percent of the remaining SO2 is removed from the stream because it interferes with the amine’s ability to react with CO2. The conditioned flue gas will be routed to the absorber, where CO2 is captured by the amine-based solvent through a chemical reaction. The CO2 rich solvent stream is sent to the regenerator, or stripper, where the CO2 is released from the solvent using low pressure steam. Heat from the steam breaks the weak bond between the CO2 and the solvent, liberating the CO2 and leaving the solvent behind for additional CO2 capture use. The captured CO2 will be compressed, dried, and then transported via pipeline to the West Ranch oil field, located near Vanderbilt, Texas.
The West Ranch oil field has produced oil continuously since 1938, first by primary production (conventional pumping) and then by water flooding (secondary production) under a series of different owners. In recent years, production rates at West Ranch have declined through conventional production techniques. In order to increase production, CO2 captured from Parish Unit 8 will be injected into the field for EOR. Carbon dioxide injection helps lower the oil viscosity and reduce forces that trap the oil in the reservoir. The CO2 provides a driving force to sweep oil from the reservoir that could not be recovered during primary and secondary phases of production. Once the oil reaches the surface, it will enter a recycle facility where it is separated from the CO2, which will be re-injected for additional use. In order to ensure that the CO2 remains permanently sequestered underground, a monitoring program to determine whether CO2 or other fluids are migrating from the production formation in the planned EOR area will be developed and implemented.