High-efficiency low LCOE combined cycles for sour gas oxy-combustion with CO2 capture

• A techno-economic analysis of oxy-fuel cycles fueled by sour gas is performed.
• Three combined cycle and two water cycle configurations are considered.
• The combined cycles, on average, have higher efficiencies and lower costs.
• Specifically, the acid resistance and SOx removal combined cycles perform best.

The growing concerns over global warming and carbon dioxide emissions have driven extensive research into novel ways of capturing carbon dioxide in power generation plants. In this regard, oxy-fuel combustion has been considered as a promising technology. One unconventional fuel that is considered is sour gas, which is a mixture of methane, hydrogen sulfide and carbon dioxide. In this paper, carbon dioxide is used as the dilution medium in the combustor and different combined cycle configurations were considered and analyzed, each with a different way of dealing with the harmful sulfur products in the working fluid. Out of these options, which included acid resistance, no-condensation and SOx removal cycles, it is found that the cycle using acid resistant materials to have the best efficiency at 45.2%. However the cost of electricity (COE) of the cycle incorporating SOx removal is about 3% lower. Comparing these combined cycles to the sour gas water cycles discussed in our previous paper (Chakroun and Ghoniem, 2015), it is evident that sour gas based oxy-combustion combined cycles generally perform better in terms of both technical and economical performance. Therefore, it is concluded that the best process cycle to use for this sour gas fuel to be the combined cycle with the SOx removal system. This high-efficiency cycle has the lowest COE out of all of the five cycles studied.