Considering Carbon Capture and Storage for Energy Generation from Municipal Solid Waste

Modern waste management practices encourage the recovery of energy from municipal solid waste after efforts to reduce, reuse, and recycle appropriate materials. Energy can be recovered through direct mass burn in a waste-to-energy (WTE) facility or through the collection and combustion of biogas generated in sanitary landfills. Many comparisons have been made although rarely using best practice assumptions for both technologies; WTE proponents tend to assume low collection efficiency while landfill proponents tend to assume low electrical conversion efficiency. In general, WTE plants can be considered to have a better environmental performance (reduced emissions) with landfill having lower total costs (social and environmental). Both strategies have similar costs when considering 77% collection efficiency and a high efficiency (30% electrical conversion) WTE plant that displaces electricity from coal. The introduction of carbon capture and storage (CCS) technologies to waste management changes the landscape by increasing the capital costs and improving the environmental performance. The air emissions are significantly reduced, practically eliminated with oxygen combustion, as the capture of CO2 requires significant flue gas scrubbing. The introduction of CCS results in a net environmental benefit for WTE plants with a turnaround electricity price of $7/MWh, as compared to landfill gas with capture. The largest environmental cost for WTE plants is the classification of fly ash as chemical waste, which is reduced with oxygen combustion. The net cost of capturing CO2 from WTE facilities is estimated at $39/t CO2, one-third of the cost of CO2 capture from landfills.