Biogas methane digester is a wastewater and solids treatment technology. When used on a farm, it processes animal waste under anaerobic conditions, yielding methane gas and reducing the volume of solids and treated liquids. The methane can be sold or used to generate electricity on the farm; the solid matter left behind is a valuable soil amendment; and the liquids become an easily applied fertilizer with plant available nutrients and low pathogen levels. Sustainable Conservation's Methane Digesters initiative provides technical assistance to farmers preparing to implement digesters.

If all 65 billion pounds of manure that are created yearly in California underwent methane digestion, the fertility and productivity of farm soils would be greatly enhanced, while supplying an estimated 200+ megawatts of power.

Digester technology could also significantly reduce the pathogens in dairy waste and help prevent polluted runoff. Additionally, methane, a powerful greenhouse gas, would be destroyed and air pollution from dairy liquids substantially mitigated. Air pollution is a significant problem in California's Central Valley, one of the worst non–attainment (any area that does not meet national primary or secondary air quality standards) areas of the country. By providing a substantial new source of revenue to the dairy producers, there is a strong economic incentive to install and utilize environmentally friendly methane digesters.

Digester technology is mostly unfamiliar to dairy producers. As a result, the technology is unlikely to be adopted without an incentive program that helps progressive dairies build and operate these systems, and demonstrate their utility for other commercial dairies to see. Sustainable Conservation has championed such a program orchestrating California Energy Commission's $15 million matching grant program. It is an important step necessary to demonstrate the viability of the technology on working dairy farms. So far, 32 dairies have applied for a grant; they are typically the more progressive dairies in their area and will be closely watched by their neighbours. If done right, this investment could radically alter the agricultural landscape, marrying environmental, economic, and renewable energy benefits.