|The basic stages of post-combustion CO2 gas treatment. Click to enlarge. Source: Purdue University.|
Alstom and American Electric Power (AEP) signed a Memorandum of Understanding to bring Alstom’s advanced sorbent CO2 capture (chilled ammonia) process to full commercial scale of up to 200 MW by 2011. This is a major step in demonstrating post-combustion carbon capture.
The technology can be applied as a retrofit to existing coal-fired plants as well as in new designs. Alstom is currently working on a 5 MW pilot project for the chilled ammonia system with EPRI.
The AEP project will be implemented in two phases. In phase one, Alstom and AEP will jointly develop a 30 MWth product validation plant that will capture CO2 from flue gas emitted from AEP’s 1,300 MW Mountaineer Plant located in New Haven, West Virginia. It is targeted to capture up to 100,000 tonnes of carbon dioxide per year.
The captured CO2 will be designated for geological storage in deep saline aquifers at the site. This pilot is scheduled for start-up at the end of 2008 and will operate for approximately 12-18 months.
In phase two, Alstom will design, construct and commission a commercial scale of up to 200 MW CO2 capture system on one of the 450 MW coal-fired units at its Northeastern Station in Oologah, Oklahoma. The system is scheduled for start-up in late 2011. It is expected to capture about 1.5 million tonnes of CO2 a year, commercially validating this technology. The CO2 captured at Northeastern Station will be used for enhanced oil recovery.
Alstom’s post-combustion process uses chilled ammonia to capture CO2. The chilled ammonia process—one of several new processes being explored for post-combustion capture—reduces the energy required to capture carbon dioxide and isolates it in a highly concentrated, high-pressure form. Studies by EPRI have indicated that ammonia scrubbing results in a 10% reduction in generated power, while the older MEA (amine scrubbing) cuts generated power by 29%.
In laboratory testing sponsored by EPRI and others, Alstom’s process has demonstrated the potential to capture more than 90% of CO2 at a cost that is less expensive than other carbon capture technologies. The isolated CO2, once captured, can be used commercially or stored in suitable underground geological sites.