Road Trip: Arriving at a New Vehicle Fuel Production System for Biogas Use

摘要

Biogas utilization is a key component of the Bio-Energy Program at Washington Suburban Sanitary Commission (WSSC), which will consolidate solids handling from multiple facilities at the Piscataway Wastewater Treatment Plant (WWTP) in Accokeek, Maryland. The solids will be treated in a thermal hydrolysis process (THP) and new anaerobic digesters. A heat and energy model, coupled with an economic model, were developed to compare the economics and performance of multiple gas treatment and use technologies and to estimate 30-year present costs, using WSSC's actual costs and local conditions. Initially, 20 different options for gas use were analyzed and the results used to reduce to 8 options for further analysis. Converting biogas to renewable natural gas for pipeline injection and use as vehicle fuel, along with a natural-gas-fired combined heat and power (CHP) system to provide power and process steam, had the lowest net present cost. This approach is expected to save over $20 million during the planning period.