California disposes approximately 30 million tons of waste in landfills each year, of which approximately 30 percent is compostable organic materials, 30 percent is construction and demolition debris, and nearly 20 percent is paper (see the 2008 Waste Characterization Study). Greenhouse gas emissions resulting from the decomposition of organic wastes in landfills have been identified as a source of emissions contributing to global climate change. Anaerobic decomposition of organic materials in landfills produces methane (CH4), a greenhouse gas with global warming potential approximately 25 times higher than carbon dioxide (CO2). Landfills emit the majority of man-made methane emissions in California. Reducing the amount of organic materials sent to landfills and increasing the production of compost and mulch are part of the AB 32 Scoping Plan.

In accordance with Assembly Bill 341 (Chapter 476, Statutes of 2011), CalRecycle is leading California’s ambitious drive toward a 75 percent reduction in the amount of waste going to landfills by the year 2020. This will be achieved through source reduction, recycling, and composting. Attaining this goal will require diverting up to 22 million tons of waste from California landfills annually.

In order to meet these goals, infrastructure must be developed to manage organic wastes and increase the production and markets for compost. Additionally, expanding anaerobic digestion infrastructure will provide organic materials managers the opportunity to earn credits for producing low carbon fuels and renewable electricity.

Three Main Drivers

  1. Infrastructure: CalRecycle fosters a regulatory and permitting environment necessary to build the 21st Century Organics Infrastructure.
  2. Scientific Research and Technology Evaluation: CalRecycle funds and supports research to answer scientific questions pertaining to waste management and climate change.
  3. Improve Economic Incentives for Organics Diversion and Markets for finished compost products: Historically, this has focused on promoting the value of compost. More recently, this includes leveraging the Low Carbon Fuel and Renewable Portfolio standards to provide additional incentives for anaerobic digestion.


To meet the goals of AB 341, it is estimated that California will need to double the size of the current organics materials management infrastructure. CalRecycle has identified barriers and corresponding solutions to help facilitate the construction and safe operation of this next-generation infrastructure:

Scientific Research and Technology Evaluation

CalRecycle funds and supports research to answer important scientific questions and to ensure program initiatives are based on the best available science. CalRecycle collaborates with other agencies to ensure shared research priorities receive prompt attention.

  • Compost-Greenhouse Gas Research. CalRecycle funded a multi-year contract with UC Davis to research the greenhouse gas impacts of compost production and use. Multiple emissions measurement techniques have been used to measure methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) emissions from a series of compost piles at a commercial compost facility in Northern California. The project includes additional field research to measure the impact of compost application on N2O emissions from intensively farmed lands—one of the largest N2O sources in California—as well as laboratory incubations checking the impact of compost on soil CH4 and N2O emissions for multiple soil types and different chemical fertilizer applications. The research will conclude in April 2014.
  • Other compost emissions research. Over the past decade, CalRecycle has funded or participated in numerous projects investigating emissions of criteria pollutants and greenhouse gases from composting piles. Most recently, CalRecycle teamed up with the San Joaquin Valleywide Air Pollution Study Agency, the Association of Compost Producers, the City of Bakersfield, Harvest Power, O2 Compost, and emissions consultant Chuck Schmidt to investigate the impacts of a commercial-scale composting system reducing criteria pollutant and greenhouse gas emissions from composting processes by employing electric conveyors for pile construction, solar-powered blowers to aerate piles, and a one-foot-thick biofilter layer to reduce emissions.
  • Evaluate Compost as a Landfill Cover. CalRecycle studied the feasibility of placing a biocover of compost over the surface of a landfill to control escaping methane.
  • In-Situ Anaerobic Digester: This CalRecycle-funded study tested an innovative concept for building anaerobic digestion and compost cells at the Yolo County Central Landfill near Woodland, CA.

Markets: Improve Economic Incentives for Organics Diversion and Markets for finished compost products

Composting and anaerobic digestion compete with low-cost landfilling and direct land application for feedstocks, reducing operators’ ability to pay for infrastructure development, product marketing, and other essentials. CalRecycle works to find ways to monetize the inherent value of advanced organics handling facilities.

  • Low Carbon Fuel Standard (LCFS) for High-Solids Anaerobic Digestion: CalRecycle staff assisted the Air Resources Board with the development of the Low Carbon Fuel Standard High Solids Anaerobic Digestion (HSAD) Pathway, which resulted in one of the lowest carbon intensities of any LCFS fuel pathway developed to date. Additionally, CalRecycle staff is currently working with ARB staff to develop a LCFS pathway for Low Solids Anaerobic Digestion (LSAD).
  • The Agriculture Working Group for the Climate Action Team coordinates efforts aimed at protecting and developing resources related to California's agricultural economy and ensures the state's ability to mitigate and adapt to climate change impacts on agriculture resources (land, livestock, water, food, and fiber) while supporting implementation of greenhouse gas emission reduction programs. CalRecycle is a participating member of this team.
  • Help Caltrans develop compost specifications and best management practices: California has more than 16,000 miles of state highways. Increasing the use of compost along those roads can help establish plants and reduce erosion after road construction or rehabilitation, and can reduce the need for and the cost of irrigating highway vegetation.
  • Landscaping: CalRecycle is working with the Climate Action Team’s Land Use Subgroup to reduce greenhouse gases by developing “Watershed-Friendly” Landscaping Guidelines for adoption and customization for local climates and conditions. The guidelines will conserve water, reduce green waste, reduce air pollution, and protect water quality. Examples of existing landscape guidelines customized for local climates and conditions include Bay-Friendly Landscaping and River-Friendly Landscape Guidelines.
  • Compost Specifications for Agriculture: CalRecycle worked with researchers to develop a range of parameters for finished compost products that will help ensure success when used by growers of specific, high-value crops, including avocados, blueberries, grapes, lettuce, strawberries, and tomatoes. Final report not yet available.