Cost-Minimization Model for Reducing Sulphur Dioxide Emission from Coal-Fired Generating Stations

Abstract

To limit emission of sulphur dioxide, an electrical utility has several available options: (i) Burn low-sulphur coal, (ii) remove SO₂ from flue gases after combustion (Flue Gas Desulphurization or FGD), and (iii) remove sulphur from coal before combustion (Physical Coal Cleaning or PCC). Options (ii) and (iii) vary in their cleaning capabilities and scale economies. Pre-cleaning of coal followed by post-cleaning of flue gases may thus be less costly than either PCC or FGD alone to obtain a given level of sulphur removal. A mathematical programming model to determine the best combination of options is developed from empirical cost data and solved for typical conditions encountered by North American utilities. Sensitivity analyses are carried out with respect to the various operating and capital costs, as well as the maximum SO. emission level. The latter enables assessment by the regulatory authorities of proposed environmental standards. Finally, we show how the model can aid a utility in directing its R&D effort by estimating the target sulphur removal capability which should be sought for each control technique and the cost saving (ROI from R&D) if successful.