Enabling Anaerobic Digestion Deployment to Convert Municipal Solid Waste to Energy
April 01, 2020
Energy Research and Development (500)
Electric Program Investment Charge - EPIC
Thomas W. Kirchstetter, Corinne D. Scown, Andy Satchwell, Ling Jin, Sarah J. Smith, Chelsea V. Preble, Jahon Amirebrahimi, Michael D. Sohn, Nancy J. Brown, Sarah Nordahl, Jay Devkota, Yijun He, Tin Ho, Randy L. Maddalena, Nicholas W. Tang, Wei Zhou
Municipal solid waste is used to produce energy at power plants and landfills, termed “waste-to-energy.” Waste products used at these plants include organic materials like as plant or animal waste, paper, cardboard, food waste, grass clippings, leaves, and wood. One method of converting organic materials to energy is anaerobic digestion of organic municipal solid waste, which produces methane-rich biogas for energy production. Waste-to-energy plants support California’s renewable energy goals and reduce landfilling and associated methane emissions. Only about 15 percent of California’s organic municipal solid waste is diverted for energy production, however, and this fraction is decreasing because of economic, regulatory, and policy barriers. A multidisciplinary research team at Lawrence Berkeley National Laboratory worked with the Zero Waste Energy Development Company and the City of San Jose to help overcome key barriers to enable sustainable scale-up of waste processing and energy production. During the project, the company more than doubled its waste intake to 90,000 tons per year. The team developed methods and quantified emission rates of greenhouse gases, ammonia, hydrogen sulfide, volatile organic compounds, and oxides of nitrogen from Zero Waste’s on- and offsite activities. The project team produced an odor transport framework and regional impact model, along with environmental life-cycle and economic analysis models, to assess net environmental, societal, and financial impacts. The team evaluated life-cycle emissions for current Zero Waste operations and alternative scenarios. Outdoor composting is the largest source of Zero Waste’s odor and greenhouse gas emissions. The plant achieves substantial emissions reductions relative to landfilling but could improve if biogas was used to fuel heavy-duty trucks. The team identified three factors to improve the business case for larger-scale plants: (i) long-term feedstock and digestate management contracts, as well as net electricity compensation prior to plant construction; (ii) investment in waste recovery to support cleaner feedstocks; and (iii) financial mechanisms to overcome large, lumpy (intermittent rather than regular) capital expenditures.