Techno-economic analysis of pretreatments to dairy manure biomass for enhanced biogas production

Various thermochemical pretreatment strategies (acid, alkaline, sulfite, alkaline-H2O2) for dairy manure anaerobic digestion were directly evaluated to analyze their techno-economic performance. Three biogas utilization scenarios (electricity, biomethane, liquefied biomethane) were considered to determine breakeven price of each biogas-derived product at which the technology becomes economically feasible. Breakeven prices for all three end-products were higher than the current market prices when no incentives were considered. Generating electricity using biogas appeared to be the most economically attractive option with the least difference and variation from current market values. Techno-economic analysis revealed that moderate-acid pretreatment performs better for larger facilities (>= 5000 animal units) whereas severe-alkaline pretreatment is preferred for smaller facilities (<= 2500 animal units). A study in the Upper Yahara Watershed (Wisconsin, USA) was performed to investigate supply chain logistical issues; here, it was found that severe-alkaline pretreatment is preferred due to the highly distributed nature of manure production and associated transportation costs.