Economic analysis of municipal power generation from gasification of urban green wastes: case study of Fultondale, Alabama, USA

Abstract

The economic viability of heat and power generation from biomass gasification is strongly influenced by the supply radius due to the low energy density of biomass relative to fossil fuels. Consequently, localized production of heat and electricity from biomass gasification is expected to play an eminent role in the future. In this study, an economic analysis was performed on a micro‐scale heat and power generation plant using urban waste from the city of Fultondale in Alabama, USA. The plant economics of heat and power production from urban biomass waste collected in Fultondale were analyzed by using a modular economic model with drying, chipping, gasification, power generation, and grid connection modules. Three gasification systems – fluidized bed, downdraft and updraft – and three power generation systems – internal combustion, steam turbine, and gas turbine – were assessed resulting in nine plant configuration scenarios. The fluidized bed gasifier and internal combustion engine plant configuration resulted in the lowest cost of electricity at ¢14/kWh for a micro‐scale installed capacity of 100kWe for a plant operating at 85% capacity with an annual green waste processing capacity of 1811 tons. The equipment and installation costs made up the largest contribution to the total capital investment whereas the operating labor and plant overhead make the largest contribution to the total annual production cost. Sensitivity analysis revealed that the plant capacity factor and the rate of return of investment had the strongest effect on the levelized cost of electricity under the best configuration.