Life Cycle Environmental and Economic Tradeoffs of Using Fast Pyrolysis Products for Power Generation

Bio-oils produced from small-scale pyrolysis may have economic and environmental benefits for both densifying agricultural biomass and supplying local bioenergy markets with fossil energy alternatives to support state policies (e.g., Renewable Portfolio Standards). We analyze the life cycle greenhouse gas (GHG), energy, and cost tradeoffs for farm-scale bio-oil production via fast pyrolysis of corn stover feedstock and subsequent utilization for power generation in the state of Pennsylvania. We evaluate the life cycle ramifications of either cofiring the biochar coproduct with coal in existing power plants for energy generation, or using the biochar as a land amendment within the agricultural sector. The results show GHG emissions of 217 and 84 g CO(2)e per kWh of bio-oil electricity for coal cofiring and land amendment, respectively. Cofiring biochar with coal displaces more fossil energy than does land application. We discuss the potential for bio-oil and biochar penetrating near-term electricity markets (c. 2015). Our analysis shows that the electricity produced from burning pyrolysis oil and biochar with variable operating costs of $93/MWh and $18/MWh, respectively, are competitive with the fuel oil and coal electricity markets in Pennsylvania within the vicinity of the agricultural sites supplying biomass in spite of the potentially higher NOx emissions due to nitrogen present in the fuel. Small scale pyrolysis bio-oil may be an economically viable and environmentally sustainable near-term option for peak power production and for meeting the state's Renewable Portfolio Standards.