|Illustration of the carbon capture plant. Click to enlarge.|
A pilot project by We Energies, Alstom and The Electric Power Research Institute (EPRI) testing an Alstom advanced chilled ammonia process (earlier post) has demonstrated more than 90% capture of carbon dioxide from the flue stream of a coal-fueled power plant in Wisconsin (the Pleasant Prairie Carbon Capture Pilot Plant). Testing at the pilot facility, using a 1.7-megawatt (electric) slipstream from the plant, captures approximately 40 tons of carbon dioxide each day. The project began in early 2008 and will conclude later this year.
The project confirmed the predicted performance of the chilled ammonia carbon capture system at an operating power plant. It achieved key research metrics around hours of operation, ammonia release, CO2 removal levels, and CO2 purity. In doing so, the partners said, the project demonstrated the fundamental viability of the carbon capture technology in real-world conditions such as changes in temperature and humidity, the inevitable starts and stops of a large power plant, and the environmental hurdles that go along with using any chemical process.
Units 1 and 2 at the Pleasant Prairie Power Plant (P4) recently were retrofitted with selective catalytic reduction (SCR) systems to control emissions of nitrous oxides (NOx) and wet flue gas desulfurization (FGD) systems to control sulfur dioxide (SO2) emissions. This retrofit also included the construction of a new chimney.
The chilled ammonia pilot system withdraws about 1% of the flue gas between the outlet of the Unit 1 or Unit 2 FGD and the stack. The gas is first cooled to condense and remove moisture and residual pollutants before it enters the CO2 absorber. There, the CO2 is absorbed by an ammonia-based solution, separating it from the flue gas.
|The three-step carbon capture process at Pleasant Prairie. Click to enlarge.|
The CO2-laden solution is heated, releasing a very pure stream of CO2. In a commercial application, this CO2 stream would be compressed and transported for use in industrial processes, such as enhanced oil recovery, or for injection and storage in a suitable underground geological formation. In this research pilot plant, however, the CO2 is remixed with the treated flue gas after process discharge sampling measurements. The entire extracted gas volume then is reintroduced into the FGD outlet transition duct where it is mixed with the FGD exhaust gas.
At maximum capacity, the pilot system has been designed to capture nearly two tons CO2/hour (equivalent to 15,000 tons/year at full capacity).
As the next step in demonstrations of increasing size, the first of two product validation facilities recently began at the American Electric Power (AEP) Mountaineer Plant in New Haven, West Virginia. A 20-megawatt electric capture system has been installed at AEP’s 1,300-megawatt Mountaineer Plant, where it will remove up to 110,000 tons of CO2 emissions annually from the flue gas stream of the plant.
The captured CO2 will be compressed, pipelined, and injected into two different saline reservoirs located approximately 8,000 feet beneath the plant site. Battelle Memorial Institute will serve as the consultant for AEP on geological storage as an extensive monitoring system will be used to track the extent of the sequestered CO2 over time.
After the Mountaineer project, Alstom plans to develop a third and final phase commercial-scale demonstration project that will be designed to capture between 1.0 – 1.5 million tons of CO2 per year. Alstom currently is working with AEP, TransAlta – a Canadian energy company and other parties to successfully develop this demonstration project.
Alstom has committed to have a commercial offering for a carbon capture technology available by 2015.
This [P4] project has been a success. It proved what we needed to know to stay on schedule to commercialize carbon capture technology for new and existing power plants by 2015, a necessary step to meet ambitious climate change targets being proposed by policy makers in the US and around the world. Alstom believes carbon capture, along with energy efficiency and a full portfolio of low carbon technologies including renewable power, will all be needed to achieve urgent CO2 reduction goals in a timely manner.
—Alstom US President Pierre Gauthier
Alstom, a leader in carbon capture technology, is pursuing 10 demonstration projects in six different countries, including the We Energies project and partnership at Mountaineer with American Electric Power. The Mountaineer project is one of two current or planned post-combustion carbon capture and storage (CCS) demonstrations for which EPRI has formed an industry collaborative to support management of testing and evaluations.
The EPRI collaborative will support the integration process/design of CO2 capture technologies and the monitoring and verification of CO2 storage, and it will assess the large-scale impacts of CO2 controls and storage on post-combustion coal-fueled generation. The data collected and analyzed by the collaborative will support efforts to advance CCS technologies to commercial scale and provide information to the public and industry on future electricity generation options.
EPRI is leading or supporting seven Industry Technology Demonstrations as part of its efforts to help develop a full portfolio of innovative technology approaches needed to make substantial CO2 emissions reductions while minimizing economic impacts.
Pleasant Prairie Carbon Capture Demonstration Project Progress Report 8 October 2009