Why Capture CO2 from the Atmosphere?

mechanical compression to provide the work of separation and will not provide competitive energy consumption. In addition to separating oxygen for the production of CO2, stoichiometric oxygen (about 20%) must be provided for hydrogen contained in the coal and for the excess required for adequate combustion (about 15%). Consequently, the estimated work for oxycombustion starts at 0.22 MWh. This estimate does not include the irreversibility of the exchangers and distillation columns in the air separation unit, nor does it include the irreversibilities of compressing the excess and leakage air along with the CO2. Amine scrubbing will be applied first on large coal-fired boilers with 12% CO2. It would also be useful with boilers fired by biomass at 14% CO2, cement plants at 25% CO2, and steel works with 25% CO2. It will be less attractive with gas-fired combined cycles at 4% CO2 or gasor oil-fired boilers or heaters at 7% CO2. Amine scrubbing, in use for nearly 80 years, is a robust technique that is ready to be tested and used on a scale appropriate for CO2 capture from coal-fired power plants. Process and solvent improvements should reduce the energy use to 0.2 MWh/ton CO2. Other advanced technologies will not provide solutions as energy-efficient or as timely to decrease CO2 emissions from conventional coalfired power plants.