Community Scale Digester with Advanced Interconnection to the Electrical Grid: High Solids Anaerobic Digestion Serving San Luis Obispo County

Anaerobic digestion is an excellent solution for extracting value from this organic waste, while additionally producing biofuels and soil amendment, reducing greenhouse gas emissions in the process. Anaerobic digester technologies have been commercially available for decades; however, widespread installation and utilization of these systems have been limited. Despite a regulatory environment encouraging renewable energy production and greenhouse gas reductions, there is a need for technology to lower the system cost as traditional methods require high capital costs to remove organic materials from the wastewater stream to create good quality slurry for an anaerobic digester system.

The California Energy Commission awarded a $4 million grant toward the estimated $9.28 million total cost of an anaerobic digestion organic waste project. HZIU Kompogas-SLO, Inc. (The Recipient), in partnership with Waste Connections and Pacific Organics, built, commissioned, and connected to the grid a state-of-the-art high-solids anaerobic digestion facility designed specifically to meet the organics diversion goals of San Luis Obispo County. This is a first-of-its-kind facility to enter the California market, and lessons learned can influence similar facilities developed to meet several state mandates to increase organic waste from municipal solid-waste sources.

The Kompogas SLO anaerobic digester was one of the fastest-constructed anaerobic digestion facilities in California. During the project, it processed 31,261 tons of organic feedstock reducing greenhouse gas emissions by 4,389.3 MTCO2e by diverting organics from business-as-usual alternatives. It also produced 7,679 tons of solid fertilizer and compost, 1.5 million gallons of liquid fertilizer and exported 2 million kilowatt-hours of renewable electricity while reducing greenhouse gas emissions by 762.2 MTCO2e.