Low-carbon power generation cycles: the feasibility of CO2 capture and opportunities for integration

Low-carbon power generation receives increasing interest due to climate warming concerns. The present article analyses three low-carbon power cycles. The focus is on the feasibility of CO2 capture and opportunities for energy and mass integration. The first power cycle is a zero-carbon solid biomass fuelled multi-step gasification gas turbine power cycle which applies multi-step solid biomass conversion being a more reversible process than one-step biomass combustion. The second zero-carbon coal fuelled oxy-gasification steam chemical looping combustion gas turbine cycle benefits from (i) improved cycle efficiency due to the increased reversibility of a chemical looping combustion process, (ii) cycle mass and energy integration due to several recirculation loops involved and (iii) extremely high CO2 capture rate due to purity of CO2/H2O mixture achieved at the outlet from a syngas reactor. The last power cycle - a biogas fuelled oxy-reforming fuel cell cycle - is superior in the feasibility of CO2 capture, i.e. CO2 is captured from CO2-enriched streams and due to the utilisation of renewable biogas, negative net CO2 atmospheric emissions are achieved.It is concluded that high CO2 capture rates are feasible from pressurised CO2-enriched streams comprising either water or hydrogen, thus necessitating oxy-fuel power cycles. Opportunities for mass and energy integration are found to be increased in systems involving closed mass and energy recirculation loops. The discussions also emphasises that low-carbon power cycles could achieve minimised exergy losses by applying more reversible energy conversion processes.