Analysis of the sorbent energy transfer system (SETS) for power generation and CO2 capture

The sorbent energy transfer system (SETS) has the potential for providing a significant reduction in CO2 emissions from gaseous fossil fuel-fired electric power plants with minimal loss in power generating efficiency. Energy transfer is accomplished in two steps so that CO2 does not come in contact with combustion air, thereby avoiding a costly and energy intensive CO2 separation step. In the first step, gaseous fuel is oxidized by reduction of an appropriate metal oxide sorbent. The gas product contains only CO2 and H2O so that pure, sequestration-ready CO2 is obtained after removing H2O by condensation. The reduced sorbent is then re-oxidized using excess air. Dual, circulating fluidized-bed or transport reactors provide continuous, steady state operation. Base case Aspen Plus simulations of the SETS process coupled to a natural gas combined cycle (NGCC) show that approximately 50% of the CO2 can be captured with an energy penalty of only approximately 5%. Base case maximum operating temperature of the two SETS reactors was limited to 900 °C to maintain the structural stability of the sorbent and adhere to operating temperature limits of particulate filters. Increased reactor temperatures would permit increased capture of CO2 with minimal additional energy penalty.