Aerobic Lagoon - Aerobic lagoons are typically uncovered earthen basins storing liquid or otherwise wet manure slurry, in which the manure is aerated to maximize biological oxidation of manure solids.
Anaerobic digester - Anaerobic digesters are closed manure treatment systems designed to maximize conversion of organic wastes into biogas. These can range from covered anaerobic lagoons to highly engineered systems. Methane gas leakage is the main source of GHG emissions; very little nitrous oxide gas is generated.
Anaerobic lagoon, liquid/slurry storage pond, storage tanks - Anaerobic lagoons are earthen basins for anaerobic digestion and storage of animal waste. Lagoons may be covered or uncovered and have a crust or no crust formation. Storage tanks and liquid/slurry storage ponds typically store slurry or wastewater that was scraped or pumped from housing systems.
Combined aerobic treatment system - This process involves removing solids using flocculation and then composting the solid stream and aerating the liquid stream of manure to oxidize manure solids.
Composting - Composting involves the controlled aerobic decomposition of organic material and can occur in different forms. The tool estimates emissions from composting in vessels, static piles, intensive windrows, and passive windrows.
Constructed wetland – A synthetic wetland typically seeded with wetland plants growing in a bed of highly porous media. Research indicates that trace greenhouse gas emissions (methane and nitrous oxide) are negligible from constructed wetlands; Carbon sinks in constructed wetlands are noted to likely be greater than trace gas emissions.
Daily Spread - In a daily spread management practice, manure is removed from a barn and is applied to cropland or pasture daily. This practice produces less methane emissions than an uncovered anaerobic lagoon because the manure is applied daily and is not stored for an extended time in anaerobic conditions.
Deposited on Pasture/Range/Paddock - This system consists of rotating animals on pasture/range/paddock where manure is left as-is to return nutrients and carbon to the land.
Land Applied - Calculated the same as daily spread
Removed Offsite - Manure is removed from entity boundaries, whether that means being removed to a facility, deposited on an adjacent farm, etc. Emissions from this manure will not be included in your COMET estimates.
Temporary Stack and Long-Term Stockpile - Manure may be stored temporarily for a few weeks in “temporary stacks” to avoid land application during unfavorable weather. Long-term stockpiles imply storage for several months or longer.
Thermo-chemical Conversion - Thermo‐chemical conversion such as pyrolysis or gasification involves the combustion of animal waste, wherein manure carbon is converted to carbon dioxide. Research indicates that trace gas emissions (methane and nitrous oxide) are negligible from thermochemical conversion. Since the carbon dioxide produced is biogenic, it is not considered to be an emission.
Solid-liquid separation - Greenhouse gases are not generated directly from separating liquid manure into solid and liquid components. Using screens, centrifuges, presses, filtration, or microscreening typically splits manure into two or more manure storage and/or management systems.