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American Electric Power (NYSE: AEP) announced two significant memorandums of understanding [MOU] regarding technologies that would reduce CO2 emissions from coal powered electric power plants.

The first MOU is with Babcock and Wilcox Company, a unit of McDermott International, Inc. (NYSE: MDR) to pursue the viability of retrofitting power plants with oxy-coal combustion (oxycombustion) to existing power plants to reduce CO2 and other emissions. Under the terms of the MOU the companies will assess the application of oxy-coal combustion as a retrofit to an existing AEP plant, and work toward the development of the first oxy-coal commercial validation project in the United States.

The second MOU is with the French company Alstom to bring Alstom’s chilled ammonia process for CO2 capture to full commercial scale of up to 200 MW by 2011. The technology has the great advantage versus other technologies of being fully applicable not only for new power plants, but also for the retrofit of existing coal-fired power plants.

B&W Oxy-Coal Combustion
Oxy-coal combustion uses pure oxygen for the combustion of coal in electricity generating plants. In this system, nitrogen that comes in with the air for the combustion process is eliminated. As a result, the exhaust gas is a relatively pure stream of CO2 that is ready for capture and sequestration or alternate uses such as enhanced oil recovery. Use of this technology is expected to result in near-zero emissions from coal-fired electric-generating facilities. B&W has established a collaboration agreement with American Air Liquide, Inc. for the continued development of the technology.

During the summer of 2007, B&W will complete a pilot demonstration of the oxy-coal combustion technology at its 30MWth Clean Environment Development Facility [CEDF] in Alliance, Ohio.

In addition, as part of the MOU, B&W and AEP will evaluate and select the most suitable existing AEP plant location for the commercial application of the oxy-coal combustion technology. B&W will provide unit performance and design approximations for potential carbon capture uses, perform preliminary site equipment layouts, prepare a detailed scope of work, and develop schedule- and budget-price estimates.

The feasibility study is scheduled for completion in the second quarter of 2008.

In addition to the work under the MOU with AEP, B&W’s Canadian subsidiary, B&W Canada, is working with a major Canadian utility to develop a supercritical pressure, pulverized coal-fired boiler and to assess the feasibility of proceeding to the construction phase on a new, near-zero-emissions, 300MW power station using the oxy-coal combustion technology. In that unit, recovered CO2 would be sold for enhanced oil recovery operations and eventually sequestrated underground in stable geologic formations.

A detailed description of tests conducted in a 5 million BTU/hr B&W pilot combustor are described in this paper. In these tests NOx emissions were significantly lower by nearly 65% when compared to air-blown combustion, and the CO2 content in flue gas was increased from 15% to 80% in O2-fired mode. The flue gas volume exiting the boiler was reduced by nearly 70%, thereby improving the economics of efficient capture, reuse, and sequestration of carbon dioxide. Because relative air infiltration was higher than would be expected in a commercial sized units even better results would be expected in commercial plants.

Swedish energy giant Vattenfall is building the first CO2-free coal-fired power plant, a 30 MW Oxyfuel pilot plant (previous post).

Alstom’s Chilled Ammonia Process

Alstom’s post-combustion process uses chilled ammonia to capture CO2. This process dramatically reduces the energy required to capture carbon dioxide and isolates it in a highly concentrated, high-pressure form. In laboratory testing sponsored by EPRI and others, Alstom’s process has demonstrated the potential to capture over 90% of CO2 at a cost that is far less expensive than other carbon capture technologies. The isolated CO2, once captured, can be used commercially or stored in suitable underground geological sites.

The 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 1300 MW Mountaineer Plant located in New Haven, West Virginia. It is targeted to capture up to 100,000 tonnes of CO2 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 promising technology. The CO2 captured at Northeastern Station will be used for enhanced oil recovery.

A Powerspan process that uses an ammonia based solutions to capture SOx, NOx,CO2, Hg and particulates from power plant flue gas have or will be demonstrated at FirstEnergy's R.E. Burger Plant in Shadyside, Ohio. Powerspan has conducted initial laboratory testing of the CO2 absorption process, which demonstrated 90 percent CO2 removal under conditions comparable to a commercial-scale absorber. Initial cost estimates indicate that the ammonia-based process could cost less than half of the next lowest-cost CO2 capture technology currently under investigation.

The Alstrom process uses chilled ammonia, which was not mentioned in descriptions of the Powerspan process, so this may be an improvement over that process. One could speculate that a heat pump could be used to chill the ammonia, which absorbs the CO2, and then the heat from condensation of the refrigerant could be used to regenerate the ammonia, releasing the CO2 for sequestration.

Both of these technologies fit in with the goals of MIT's Future of Coal report, mentioned in a previous post. In fact, oxycombustion was mentioned specifically as a potential technology that could reduce CO2 emissions.

Source: American Electric Power Looks to Reduce Coal CO2 Emissions