Dairies are in the cross hairs of reducing methane emissions in California. Manure methane emissions are the prime target. The legislative expectation (SB 1383) is to reduce methane emissions by 40% of the 2013 amounts. This is a very ambitious target. Manure maintained in anaerobic conditions (wet) is associated with methane emissions. To reduce methane emissions, manure can be collected and maintained in an anaerobic environment and biogas is collected and used. California has invested in the goal to reduce emissions with cost sharing (up to 1.5 million dollars) for development of anaerobic digesters with biogas used for fuel (not to power a gen-set). Alternatively, manure can be removed or prevented from getting into a liquid stream to reduce methane emissions. Since anaerobic digesters are not for every dairy, California has invested in Alternative Manure Management Practices (AMMP). These practices include:
1. Solid liquid separation in conjunction with:
- open solar drying;
- closed solar drying;
- forced evaporation with natural gas fueled dryers;
- daily spread;
- solid storage;
- composting in vessel;
- composting in aerated static pile;
- composting in intensive windrows;
- composting in passive windrows with composting of solids or flush to scrape with composting of solids.
2. Conversion from flush to scrape manure collection in conjunction with one of the “a” through “i” options mentioned above.
3. Eligible pasture-based management practices include:
- conversion of a non-pasture livestock operation;
- increasing the amount of time livestock spend at pasture; and/or
- construction of a compost bedded pack barn.