California Air Resources Board

Assembly Bill (AB) 1900 (Gatto, Chapter 602, Statutes of 2012) requires the California Public Utilities Commission (CPUC) to develop standards for constituents of concern in biogas to protect human health, pipeline integrity, and safety. It also requires the Office of Environmental Health Hazard Assessment, in consultation with the California Air Resources Board (CARB), to identify constituents of concern in biogas and determine health protective levels and exposure scenarios and health risks for those contaminants. Separately, AB 1900 also requires the California Energy Commission (CEC) to identify impediments that limit procurement of biomethane in California, and requires CPUC to adopt policies and programs that promote in-State production and distribution of biomethane.

This study, funded by CARB and conducted by the University of California, Davis (UCD), is the first part of a multi-phase research process to enhance California data on constituents of concern in biogas and biomethane (biogas upgraded to pipeline standards). Researchers sampled one landfill, one food waste digester, one food waste digester with landfill gas, and two dairies, and evaluated constituents of concern including but not limited to volatile organic compounds, polychlorinated biphenyls, metals, and pesticides. CEC funded UCD to conduct a phase II study that analyzed biogas and biomethane samples from two wastewater treatment plants, two dry green waste and solid waste facilities, one wet green waste and solid waste facility, and two landfills. As of fall 2020, CARB is funding phase III of this research, which will analyze biogas and biomethane sample streams from food waste digesters, dairy farms, a landfill, and three different compressed natural gas streams.