Techno-economic evaluation of membrane technology for pre-combustion decarbonisation: Water-gas shift versus reforming

A techno-economic evaluation of the application of membrane reactors in natural gas combined cycles with CO2 capture is presented. The electrical efficiency, capture efficiency, required membrane surface area and cost of CO2 avoided are presented for power plants integrated with membrane reformers as well as membrane water gas shift reactors. For applications in CO2 capture, membrane water-gas-shift is more suited than membrane reforming. The lower hydrogen partial pressure in a membrane reformer compared to membrane WGS causes high investment costs, because the membrane area is high and compression of the hydrogen fuel before entering the gas turbine is necessary. A significant increase in operating temperature, possibly combined with a higher feed pressure could improve the performance of membrane reformers. For the various options of upstream reforming in membrane water-gas shift, gas heated reforming is the preferred option with autothermal reforming as second best.