The project accepted a PG&E 20-year Power Purchase Agreement with full operation and has collected operational data for one year commencing in the first quarter of 2018. Electrical production from the digester exceeded expected production during 2018. Monthly gross electrical production was more than 680,000 kWh. The project was completed in March, 2019.
The project uses biogas derived from on-site dairy manure to generate low-carbon, renewable electricity and to achieve high overall efficiency by capturing waste heat from the power generation system and using it to drive an absorption chiller. The absorption chiller is designed to convert waste heat into chilling capacity, which will be used to chill milk produced by the dairy cows. New absorption chiller capacity directly offsets electricity consumption from existing electric chillers. Combining renewable generation with waste heat collection and cooling, the project increases energy efficiency of the existing dairy by an estimated 10% or more, while also reducing peak grid power demand.
The project will improve odor control, through hydrogen sulfide removal, which is important to the dairy employees and benefits the local community. Progress has been made in limiting hydrogen sulfide (H2S) emissions from a high of 5000 ppm to under 100 ppm while utilizing only the air injection system, and under 7 ppm with a final iron sponge scrubbing.
By advancing digester economics and design, through efficient manure management practices, the project will help lower dairy management and operation costs.
Environmental & Public Health
The double-lined lagoon enhances groundwater protection by minimizing leaching of manure into groundwater. Climate Trust estimates the carbon offsets that would likely be generated over the project’s 10 year crediting period at 206,060 tonnes CO2e gross based on CARB’s Livestock Protocol. The environmental benefits of this project include reduction of 11,012 metric tons of carbon dioxide (CO2) equivalents, and holding exhaust emissions to under 6.4 ppm of nitrous oxides (NOx) and 57 ppm carbon monoxide (CO) which are both well under California Air Resources Board (CARB) limits of 11 ppm NOx and 210 ppm CO.
Key Project Members
ABEC #4 LLC CE&S Dairy Biogas