Aqueous NH3 in CO2 Capture from Coal-Fired Thermal Power Plant Flue Gas: N-Fertilizer Production Potential and GHG Emission Mitigation

Abstract

Carbon dioxide (CO2) emission from stationary point sources connected to combustion facilities using fossil fuels in addition to other industrial sources is adversely affecting the climate on earth. Thus capturing CO2 from the combustion sources followed by its safe stabilization or storage constitutes an important target. Legion of researches have so far been undertaken to develop absorbents, adsorbents, and membranes to remove CO2 from combustion facilities. Capturing CO2 from the post-combustion flue gas by the chemical absorption method using aqueous ammonia (NH3) has been given serious attention by the researchers considering the advantages of high CO2 capture efficiency, ease of operation, and lower investment cost. Life cycle CO2 emission analysis revealed that capturing CO2 from the exhaust of flue gas of a coal-fired thermal power plant (TPP) using aqueous NH3 could be a plausible option. The possible solid reaction products of aqueous NH3 based multipollutant capture of the flue gas from the TPP targeting for CO2 capture would be ammonium sulfate [(NH4)2SO4], ammonium nitrate [NH4NO3], and ammonium bicarbonate [NH4HCO3]. These products have the potential to serve as N-fertilizer. In this communication, the present status of investigations on the aqueous NH3 based CO2 capture process is analyzed gathering information from the existing literatures. Given the tremendous scope of research in India, the current national research potential could be gainfully utilized for envisaging the CO2 capture by aqueous NH3 in coal-fired TPP. In this regard, multisectoral research programs could be proposed in a planned manner for making use of the available resources in the country with the coordinated approach of few important streams such as academia, thermal power, fertilizer, agriculture, environment, and climate change. Recommendations are made for development of suitable CO2 capture technology in Indian coal-fired TPPs.