National and regional generation of municipal residue biomass and the future potential for waste-to-energy implementation

Municipal residue biomass (MRB) in the municipal solid waste (MSW) stream is a potential year-round bioenergy feedstock. A method is developed to estimate the amount of residue biomass generated by the end-user at the scale of a country using a throughput approach. Given the trade balance of food and forestry products, the amount of MRB generated is calculated by estimating product lifetimes, discard rates, rates of access to MSW collection services, and biomass recovery rates. A wet tonne of MRB could be converted into about 8 GJ of energy and 640 kg of carbon dioxide (CO2) emissions, or buried in a landfill where it would decompose into 1800 kg of CO2 equivalent (in terms of global warming potential) methane (CH4) and CO2 emissions. It is estimated that approximately 1.5 Gt y−1 of MRB are currently collected worldwide. The energy content of this biomass is approximately 12 EJ, but only a fraction is currently utilized. An integrated assessment model is used to project future MRB generation and its utilization for energy, with and without a hypothetical climate policy to stabilize atmospheric CO2 concentrations. Given an anticipated price for biomass energy (and carbon under a policy scenario), by the end of the century, it is projected that nearly 60% of global MRB would be converted to about 8 EJ y−1 of energy in a reference scenario, and nearly all of global MRB would be converted into 16 EJ y−1 of energy by the end of the century under a climate policy scenario.