Agricultural Methane Abatement
Several biological processes important to our agriculture and food systems emit methane, a greenhouse gas that is as much as thirty times more harmful to the environment than carbon dioxide.
The most significant source of methane is livestock—especially cattle, swine, and sheep. Adjusted feeding practices and other technical interventions can lower these enteric emissions, and controlling the way manure decomposes can reduce emissions of both methane and nitrous oxide.
Another important source of agricultural methane is decaying plant and food matter, particularly in landfills. The adoption of methane-recovery technologies by most U.S. landfills, as well as increasing rates of recycling and composting, has kept these emissions on a downward trend over the past two decades, but more can still be done to accelerate these reductions. Polices to reduce agricultural methane should include provisions to ensure direct benefits to low-income and historically disadvantaged communities centered around agricultural industries.
High Capital Costs
Since methane abatement from livestock waste and food waste is capital intensive, access to financing is key to the widespread adoption of new technology. Anerobic digestion facilities and methane control systems at landfills require large upfront capital investments that may be hard to finance through traditional loans due to uncertain future revenue streams. Reducing enteric fermentation through livestock feed additives also requires capital investments in research and development (R&D) of advanced feed technologies. But as many of these technologies are in the early development stages, traditional financing is often not available.
Land Use and Permitting
Methane abatement from livestock waste and food waste can require large-scale facilities to contain and digest methane emissions. These facilities must meet air, water, health and safety, and land-use requirements, and zoning ordinances and permitting requirements can delay or even prevent their construction. Despite advancing technologies that reduce the impacts of handling livestock and food waste, as well as strict requirements to meet local and national codes for safety, permitting and zoning remain barriers to the widespread adoption of methane-reduction mechanisms. Land use and permitting must ensure that reductions in methane emissions do not increase local air pollution that they and maintain soil and water quality.
Many consumers are wary of the potential health impacts of some methane-abatement strategies, such as feed additives that may reduce enteric fermentation. Public sentiment can also prevent installation of methane capture facilities for livestock and food waste. Policies that support advanced technologies that limit the impact of waste-to-energy facilities on the local community, as well as neighborhood outreach, can help limit the negative public perception of critical methane-abatement technologies.
Technology Innovation Examples
Cattle account for approximately 10 percent of total global greenhouse gas emissions, including about 60 percent of global N2O and 50 percent of methane. (Livestock produce significant amounts of methane as part of their normal digestive processes.) Simply making cattle production more efficient, by increasing cattle productivity while decreasing enteric emissions, is in the interests of both farmers and the environment.
Technological opportunities to achieve this include tools to increase livestock productivity and the development of advanced ruminant dietary additives that reduce enteric methane emissions. Some feed additives can inhibit the microorganisms that produce methane in the rumen and subsequently reduce emissions. These methane-reducing feed additives and supplements can be synthetic chemicals, natural compounds (such as tannins and seaweed), or fats and oils.
Greenhouse gas emissions from animal manure represent about 2 percent of global emissions. The breakdown of manure applied to soils and pasture results in significant emissions of N2O, while manure management in low-oxygen environments such as open lagoons results in significant methane emissions globally.
Opportunities to reduce manure emissions include the development of advanced anaerobic digester technologies. Anaerobic digestion is a series of biological processes in which microorganisms break down biodegradable material in the absence of oxygen. One of the end products is biogas, which can be combusted to generate electricity and heat or processed into renewable natural gas and transportation fuels. Separated digested solids can be composted, utilized for dairy bedding, directly applied to cropland, or converted into other products. Nutrients in the liquid stream can be used as fertilizer. Environmental justice organizations have opposed methane digesters due to their potential impacts on local air, water, and soil quality. Policies supporting methane digesters must ensure that rural communities benefit environmentally and economically. They may also require provisions limiting the on-site combustion and flaring of methane.