Dry-anaerobic digester creates CNG for company’s collection fleet.
The new facility uses dry-anaerobic digestion (AD) technology to generate clean-burning compressed natural gas (CNG), which will power the company’s collection fleet. The fully enclosed system is set to process 11,200 tons of material per year. Material used in the process includes food scraps and food-soiled paper collected from businesses in the company’s service area, which includes South San Francisco, Brisbane, Millbrae and San Francisco International Airport.
“We’re excited about the new digester because it allows us to turn compostable food scraps into fuel for the very trucks that collect those materials. It’s a truly closed loop system,” says Doug Button, president of South San Francisco Scavenger and Blue Line Transfer, based in South San Francisco. “Plus, the process keeps organic waste out of the landfill and cuts greenhouse gas emissions — the communities we serve, the environment and our company.”
Most anaerobic digesters currently online in California generate electricity from methane. Blue Line Transfer’s system, made by
Zero Waste Energy LLC, Lafayette, California, says it is the first dry-anaerobic digester in the country to produce CNG transportation fuel. Besides producing up to 500 diesel gallon equivalents (DGE) per day of carbon negative biogenic (renewable) CNG, the process provides digestate, a nutrient-rich substance that will be matured into certified organic compost.
The launch of the facility is part of SSFSC’s expanded business collection program for food scraps and food-soiled paper. A campaign is underway to increase the number of commercial customers participating in the program. The company plans to expand the food scrap collection program to residents as well.
