In the race to develop new ways of generating affordable electricity with minimal environmental impact, Alstom is leading commercial development of a new technology that enables the capture of greenhouse gas emissions from fossil fuels. The new technology burns coal or any fossil fuel in oxygen, rather than air, utilizing Alstom’s advanced pulverized coal (PC) and circulating fluidized bed (CFB) boilers.
Oxygen combustion (also known as oxyfuel firing) produces a flue gas of concentrated carbon dioxide (CO2), which can be captured and sequestered, preventing it from entering the atmosphere. One promising scenario is to use the CO2 commercially for enhanced oil recovery (EOR) and/or enhanced gas recovery (EGR), which also effectively sequesters it.
In June 2005, Alstom completed the third successful test of the oxyfuel fired CFB in its 3 MWth pilot plant at the Power Plant Laboratories in Windsor, CT. In this test and two earlier tests in 2004, an Eastern medium volatile bituminous coal and a petroleum coke were tested for a total of nearly 300 hours.
These tests demonstrated the successful operation of the CFB fired with high concentrations of oxygen instead of air. The tests also produced important data on heat transfer coefficients, combustion efficiency, emissions of major pollutants (carbon monoxide, sulfur dioxide, and nitrogen oxides), and trace emissions (volatile organic compounds, mercury, and other metals). This data also forms the design basis for scale-up of oxyfuel firing to a demonstration plant.
Based on the successful pilot scale results, Alstom is now developing a conceptual design of an 80 MWe air-fired CFB retrofitted to oxyfuel firing. This design is geared toward the first commercial demonstration plant of its kind in North America.
According to Dr. Woody Fiveland, senior technical fellow at Alstom’s Power Plant Laboratories: “The successful performance of oxyfuel firing during these tests is an important milestone in offering carbon capture ready solutions to our customers. Alstom remains committed to achieving competitive fossil fuel power generation with near-zero emissions.”
Alstom’s development of oxyfuel firing technology is proceeding as part of the U.S. Department of Energy National Energy Technology Laboratory’s Carbon Sequestration Program. Funding for the current work is partially provided by the US DOE. This research will help attain the US President’s Global Climate Change Initiative by providing a highly concentrated, sequestration-ready stream of CO2 without costly separation. Sequestration of the CO2 enriched flue gas would also help achieve goals of the ‘Clear Skies’ by preventing emissions of SO2, NOx and other pollutants.
In the framework of national and EU funded projects, Alstom is also working in close collaboration with utilities and the academia towards the realisation of an oxygen-fired PC technology demonstration. Main development areas are combustion efficiency, heat transfer, boiler design and environmental equipment for zero emissions from coal utilisation.
In parallel, Alstom is actively participating with many partners in the European Advisory council to create the European Technology Platform for Zero Emissions Fossil Fuel Power Generation. It is setting the vision for the technology and market measures that will be necessary to shape Europe’s fossil fuel power generation industry to address the zero emissions issue.