Climate Change Impacts of Electricity Generated at a Waste-to-Energy Facility.

Waste-to-energy (WTE) facilities combust both biogenic and nonbiogenic materials comprising municipal solid waste (MSW) in addition to managing waste, leading to a lack of clarity on the life cycle climate change impact (LCCCI) as an electricity generator. In order to investigate the LCCCI of this resource, a cradle-to-gate life cycle assessment (LCA) of a WTE facility in Jamesville, NY, was performed utilizing system expansion to account for avoided landfilling emissions, additional metals recycling, and the loss of potential electricity generation from landfill gas. The LCCCI of electricity from this WTE facility ranges from 0.664 to 0.951 kg CO2eq/kWh before system expansion, which reduced the impact to -0.280 to 0.593 kg CO2eq/kWh when accounting for avoided waste management emissions. Combustion is the leading contributor of GHG emissions from cradle-to-gate, and sensitivity analysis indicates that the nonbiogenic fraction of the waste most significantly influences the LCCCI before including cobenefits. The fraction of methane from landfills that is not captured is the most influential variable under system expansion. Before system expansion, the LCCCI of this system is comparable to that of electricity from fossil fuels. With system expansion, the LCCCI ranges from below that of renewable energy to comparable to natural gas based electricity. These results disagree with claims in the reviewed literature that WTE can avoid GHG emissions overall, although avoided emissions reduce the magnitude of its impact.

Geographic analysis of the feasibility of collocating algal biomass production with wastewater treatment plants.

Resource demand analyses indicate that algal biodiesel production would require unsustainable amounts of freshwater and fertilizer supplies. Alternatively, municipal wastewater effluent can be used, but this restricts production of algae to areas near wastewater treatment plants (WWTPs), and to date, there has been no geospatial analysis of the feasibility of collocating large algal ponds with WWTPs. The goals of this analysis were to determine the available areas by land cover type within radial extents (REs) up to 1.5 miles from WWTPs; to determine the limiting factor for algal production using wastewater; and to investigate the potential algal biomass production at urban, near-urban, and rural WWTPs in Kansas. Over 50% and 87% of the land around urban and rural WWTPs, respectively, was found to be potentially available for algal production. The analysis highlights a trade-off between urban WWTPs, which are generally land-limited but have excess wastewater effluent, and rural WWTPs, which are generally water-limited but have 96% of the total available land. Overall, commercial-scale algae production collocated with WWTPs is feasible; 29% of the Kansas liquid fuel demand could be met with implementation of ponds within 1 mile of all WWTPs and supplementation of water and nutrients when these are limited.