The U.S. Department of Energy is providing financial assistance to Petra Nova Parish Holdings, LLC (Petra Nova) to demonstrate the addition of a commercial-scale post-combustion carbon capture technology at the coal-fired W.A. Parish Generating Station 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 stream equivalent to 240 Megawatts (MW) 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. This advancement is 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 MW project was determined to be too small to immediately induce significant oil production.
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 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.
Additional development and demonstration is needed to improve the cost and efficiency of technologies that capture and store carbon dioxide (CO2) emitted from coal-based electric power generating facilities. Carbon capture and storage (CCS) technologies offer great potential for reducing CO2 emissions and mitigating global climate change, while minimizing the economic impacts of the solution.
The U.S. Department of Energy (DOE) is providing financial assistance through the Clean Coal Power Initiative (CCPI) Round 3, which includes funding from the American Recovery and Reinvestment Act (ARRA), to demonstrate the commercial viability of next generation technologies that will capture and sequester CO2 emissions. Once demonstrated, the technologies can be readily considered in the commercial marketplace by the electric power industry.
The W.A. Parish Post-Combustion CO2 Capture and Sequestration Project represents an important step in advancing the commercialization of technologies that capture CO2 from the flue gas of existing power plants. The addition of CO2 capture capability to the existing fleet of power plants will enable those plants to continue to produce clean electricity and simultaneously reduce the impact of CO2 emissions. Specific project benefits are as follows:
- The capture and sequestration of up to 1.4 million metric tons of CO2 per year from a W.A. Parish Generating Station flue gas stream.
- Increased domestic oil production in the U.S., which contributes to national energy security.
- A path forward for existing coal-fired power plants to continue energy production while meeting environmental sustainability goals.
The project goal is to advance fully integrated CCS technologies from the demonstration stage to commercial viability. The project objective is to demonstrate CO2 removal from treated flue gas from an existing coal-fired electrical generating station and the compression and transport of the pipeline quality CO2 to a sequestration site where it will be used for EOR.
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