Techno-economic assessment of sour gas oxy-combustion water cycles for CO2 capture

• A techno-economic analysis of oxy-fuel water cycles fueled by sour gas is performed.
• Two cycle configurations are considered: acid resistance and SOx removal.
• A better performance by the acid resistance cycle is observed.
• However the SOx removal cycle is found to have a lower levelized cost of electricity.

Growing energy demand coupled with the threat of global warming call for investigating alternative and unconventional energy sources while reducing CO2 emissions. One of these unconventional fuels is sour gas, which consists of methane, hydrogen sulfide and carbon dioxide. Using this fuel poses many challenges because of the toxic and corrosive nature of its combustion products. A promising technology for utilizing it is oxy-fuel combustion with carbon capture and storage, including the potential of enhanced oil recovery for added economic benefits. Although methane oxy-fuel cycles have been studied in the literature, using sour gas as the fuel has not been investigated or considered. In this paper, water is used as the diluent to control the flame temperature in the combustion process, and the associated cycle type is modeled to examine its performance. As the working fluid condenses, sulfuric acid forms which causes corrosion. Therefore, either expensive acid resistant materials should be used, or a redesign of the cycle is required. These different options are explored. A cost analysis of the proposed systems is also conducted to provide preliminary estimates for the levelized cost of electricity (LCOE). The results show the acid resistance cycle with a 4.5% points increase in net efficiency over the cycle with SOx removal. However there is nearly a 9% decrease in the cycle's LCOE for the latter case.