D7.5 Oxygen enriched EGR in WtE plants: opportunities and challenges for enhanced CO2 capture

The CO2 content in the flue gases of waste-to-energy plants can be increased using oxygenenriched combustion with exhaust gas recirculation. It is expected that the energy consumption and sizes of equipment of the capture unit are reduced. However, the production of oxygen-enriched air increases energy consumption and CAPEX. This deliverable presents a techno-economic study on the performance of typical CO2 capture processes for a waste to energy plant using oxygenenriched combustion. The capture processes include (1) solvent capture using the CO2 solutions by Saipem solvent technology, MEA and AMP-PZ, (2) membrane separation, and (3) oxy-fuel combustion. It is found that oxygen-enriched combustion increases the overall energy consumption for solvent capture processes since the reductions in energy consumption related to CO2 capture are small. The overall energy consumption for the membrane capture is reduced by 17.5% when the CO2 content of the flue gases increases to 27.5%. The oxy-fuel combustion is also competitive when considering energy consumption. Cost analyses have been performed for the MEA and for the membrane capture processes. It is found that the overall annualized cost increases for the MEA capture process while it is reduced for the membrane capture process. Trade-off between the reduction in cost for the membrane process and the increased complexity of the advanced oxygen enriched combustion configuration with recycle train must be considered when selecting a suitable configuration when considering mebrane based processes for CO2 capture from WtE plants. The oxygen-enriched combustion is thus more attractive for membrane capture processes in the range of CO2 contents studied.