Comparison of flue gas desulphurization processes based on life cycle assessment

Abstract

In this work, the environmental impact assessment is prepared for three different flue gas desulphurization (FGD) processes: (1) intra-furnace sulphur removal during coal combustion with limestone addition, (2) FGD with wet lime scrubbing, (3) regenerative copper oxide flue gas clean-up process. The evaluation and ranking of the three processes according to their environmental impacts is completed for the treatment of as much flue gas that contains 1 kg sulphur. The assessment of the environmental impacts is carried out with the Eco-indicator 99 life cycle impact assessment methodology based on life cycle inventories collected from existing coal fuelled power plants. The environmental assessment is prepared for three different scenarios according to degree of the utilization of the by-products obtained during the desulphurization: (1) zero utilization, (2) full utilization, (3) utilization according to industrial statistics. The results show that all the three investigated FGD processes have about 80% lower environmental impact than the uncontrolled release of sulphur oxides into air. Intra-furnace limestone addition and wet scrubbing processes use similar principal of physical chemistry and they have similar environmental indices. The basis of the regenerative process is a sorption/reduction/oxidation cycle that has higher SO₂ removal efficiency than the two other processes. This higher efficiency results in a significantly lower environmental impact.