Thermodynamic foundation of the zero emission concept

By definition, zero emission coal plants generate power without any purposeful emissions to the atmosphere. This is only possible if all the CO₂ produced is captured and if one avoids the admixture of nitrogen from the air with fuel gases. Because zero emission coal plants have no smoke stack, they emit no pollutants to the air. Zero emission plants circulate a gas stream to which fresh fuel is added and from which spent fuel and impurities are removed as solids or liquids. Coal is gasified via hydrogenation (hydrogasification), steam reforming or CO₂ gasification (Boudouard reaction). In one class of zero emission coal plants, the gas (not necessarily hydrogen) is oxidized in a fuel cell and the resultant water and CO₂ are partially removed before returning the remaining gas to the gasifier. The high conversion efficiency of zero emission power plants, which exceeds 70% even in realistic designs, stems from combining fuel cells with careful heat management. The paper generalizes the concepts and outlines the thermodynamic basis of zero emission power plants.