Removing carbon dioxide from fossil power plants’ flue gas
For coal-fired power plants, low carbon dioxide emissions are a key requirement. Post-combustion capture offers a way forward.
Coal-fired power plants remain one of the most important sources of power today. However, their carbon dioxide emissions are a significant burden on the environment and are seen as a cause of climate change. Curbing these emissions effectively calls for solutions capable of cutting carbon output on a massive scale. Post-combustion capture – or POSTCAP – is a method of removing carbon dioxide extensively from the flue gas of coal- and gas-fired power generating facilities. It involves a wet process based on solvents – of an amino acid salt, for example – to absorb the carbon dioxide. The captured carbon is later desorbed by heating the solvent.
Siemens’ second-generation POSTCAP technology, an advanced capture process, performs chemical absorption with an aqueous solution of an amino acid salt (AAS). Suitable for retrofitting existing plants as well as equipping new-build power plants, Siemens’ POSTCAP package encompasses process development, basic and detail engineering, procurement and commissioning (EPC).
A pilot project currently underway at E.ON’s Staudinger coal-fired power plant, near Hanau, in Germany, aims to thoroughly test the solvents and process design, with a special emphasis on operational and environmental factors. The focus of the initial test phase was on the long-term chemical stability of the solvent, the effectiveness of the process, and the emissions under real-life operating conditions. After more than 3,000 operating hours since the installation was commissioned in September 2009, it’s evident that the method developed by Siemens absorbs more than 90 percent of the carbon dioxide and has virtually no solvent emissions. It also consumes significantly less energy than conventional methods.
| Carbon dioxuide capture and pressurization cause relatively low loss in overall plant efficiency (8.5 percentage points) |
| Low solvent degradation |
| Suitable for retrofits as well as new plants |
| Available as a turnkey solution |
| Comprehensive solution for entire process chain – from power plant integration to the design and manufacture of carbon dioxide compressors for feeding pipelines |
| Carbon dioxide capture rates as high as 90 percent or more |
| Lowest solvent slip |
| AAS solvent with no negative environmental impact and good HSE characteristics (non-toxic, biodegradable, non-inflammable, non-explosive, odorless, no inhalation risk) |
| Further reduction in other flue gas pollutants, including NOx and SOx, as a side benefit |
2011-Feb-28 | Author
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