Composition and Toxicity of Biogas Produced from DifferentFeedstocks in California

Biogas is a renewable energy source composed of methane, carbon dioxide, and other trace compounds produced from anaerobic digestion of organic matter. A variety of feedstocks can be combined with different digestion techniques that each yield biogas with different trace composition. California is expanding biogas production systems to help meet greenhouse gas reduction goals. Here we report the composition of six California biogas streams from three different feedstocks (dairy manure, food waste and municipal solid waste). The chemical and biological composition of raw biogas is reported and the toxicity of combusted biogas is tested under fresh and photo-chemically aged conditions. Results show that municipal waste biogas contained elevated levels of chemicals associated with volatile consumer products (VCPs) such as aromatic hydrocarbons, siloxanes, and certain halogenated hydrocarbons. Food waste biogas contained elevated levels of sulfur-containing compounds including hydrogen sulfide, mercaptans, an...