| Summary: | According to the Intergovernmental Panel on Climate Change (IPCC), carbon dioxide (CO2) concentration in the atmosphere has increased from its pre-industrial value of 280 parts per million by volume (ppmv) to 384 ppmv. IPCC predicts that CO2 concentration in the atmosphere will rise to 550 ppmv by the year 2100, if anthropogenic emissions continue to increase. The average temperature at the Earth's surface could increase 1.8-4.0K above the 1990 levels by the end of this century. Such warming is anticipated to cause sea level rise, increased intensity and frequency of extreme weather events, ice shelf disruption, and changes in rainfall patterns. As a result, reducing CO2 emissions from anthropogenic sources is a high priority. Combustion of fossil fuels for power generation is the major contributors of CO2 emission into the environment. Currently, CO2 chemical absorption using monoethanolamine (MEA) as a solvent is the best available option for CO2 capture from flue gas streams. The issue with this technology is the high capture cost which ranges from $50/metric ton to $70/metric ton CO2 avoided. Energy consumption by the process contributes to 60% of the cost. Thus, use of solvents with lower heats of absorption is preferable. A novel process called Integrated Vacuum Carbonate Absorption Process (IVCAP), which employs potassium carbonate (PC) as a solvent, has been proposed. Since chemical affinity of CO2 to K2CO3 is weak compared to MEA, the regeneration of CO2-rich solution can be operated under vacuum at a lower temperature. Hence, a low quality steam from the power plant steam cycle can be used as the heat source for the regeneration. IVCAP process is expected to have 25-30% lower energy requirements as compared to an MEA-based process. However, compared with the MEA solution, PC solutions with low heats of absorption generally exhibit much slower CO2 absorption rates. Hence, a biological catalyst, carbonic anhydrase (CA) was investigated to promote the rate of CO2 absorption into select PC solutions. ...
|
|---|