ESTIMATING ENVIRONMENTAL BENEFITS ASSOCIATED WITH A REGIONAL DIGESTER TREATING DAIRY MANURE

Inland Empire Utilities Agency (IEUA), a municipal water district serving California's Chino Basin region, provides utility-related services to seven communities and 700,000 residents, including a number of local dairy operations. Dairy farms are California's largest agricultural sector and dairy manure is one of the most severe sources of air and water pollution in the Chino Basin as well as the Central Valley. As part of an overall Organics Management Strategy program, IEUA developed and implemented a manure anaerobic digestion demonstration project for the collection and treatment of dairy manure. The state-of-the-art anaerobic digesters operate as a centralized manure management facility, and currently process manure from 14 dairy farms in Chino Basin. Future plans for expansion will increase the service area.A model was developed to quantify and verify methane and other greenhouse gas emission reductions and the environmental benefits of renewable energy produced by the digesters. Baseline emissions of methane, nitrous oxide, and ammonia associated with dairy manure management, including land application, prior to implementation of the digester project were estimated using farm-specific operational data. Post-digester emissions, including emissions associated with the transportation of manure and combustion emissions from the digesters, were calculated and used to estimate greenhouse gas reductions achieved through the operation of the anaerobic digesters at IEUA facilities. A monitoring plan was also developed to identify the data inputs required by the emissions model in order to monitor emissions and reductions associated with the project.The products and tools developed in this project are expected to assist with the development of verified and tradable emission reductions and renewable energy green tags resulting from digester activity.