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ARS Home » Pacific West Area » Riverside, California » Agricultural Water Efficiency and Salinity Research Unit » Research » Publications at this Location » Publication #407275
Research Project: Water Management for Crop Production in Arid and Semi-Arid Regions and the Safe Use of Alternative Water Resources

Location: Agricultural Water Efficiency and Salinity Research Unit

Title: The impact of an anaerobic digester on seasonal manure management CH4 emissions from a dairy farm in the San Joaquin Valley of California

Author
item PREBLE, CHELSEA - Lawrence Berkeley National Laboratory
item ROJAS ROBLES, NIDIA - University Of California, Riverside
item THIRUVENKATACHARI, RANGA - University Of California, Riverside
item PEXTON, JOYCE - University Of California, Davis
item Anderson, Raymond - Ray
item VENKATRAM, AKULA - University Of California, Riverside
item MEYER, DEANNE - University Of California, Davis
item HOPKINS, FRANCESCA - University Of California, Riverside

Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 10/5/2023
Publication Date: 12/11/2023
Citation: Preble, C., Rojas Robles, N.E., Thiruvenkatachari, R.R., Pexton, J., Anderson, R.G., Venkatram, A., Meyer, D., Hopkins, F.M. 2023. The impact of an anaerobic digester on seasonal manure management CH4 emissions from a dairy farm in the San Joaquin Valley of California. American Geophysical Union. N/A.

Interpretive Summary:

Technical Abstract: In California, livestock manure management methane (CH4) emissions account for about 26% of the state’s total CH4 inventory. California has set a target to reduce CH4 emissions to 40% below 2013 levels by 2030. Installation of anaerobic digesters is expected to play a significant role in reaching CH4 reduction targets in the dairy and livestock sector. Anaerobic digesters capture CH4 produced from liquid manure to be used as renewable biogas and reduce the volatile solids in the effluent available for methanogenesis during subsequent storage. We measured CH4 from liquid manure management complex at a dairy farm in California’s San Joaquin Valley before and after installation of a covered lagoon anerobic digester. In seasonal field campaigns, CH4 mole fraction enhancements were measured using a mobile platform with cavity ringdown spectrometers around manure lagoons, settling basins (pre), and the anaerobic digester (post). The median CH4 mole fraction at the manure lagoon complex dropped by roughly two-thirds post-digester and ranged from 6.9 to 17.9 ppm pre digester installation and from 2.7 to 5.4 ppm post digester installation depending on the season. The maximum observed CH4 mole fractions were 113.4-156.2 ppm and 25.8-79.2 ppm before and after digester installation, respectively, and varied by season, with the highest CH4 mole fractions observed in winter both before and after digester installation. Implementation of anaerobic digestion decreased the annual median and maximum CH4 mole fraction observed at the manure lagoon complex by 72.4 and 64.1% respectively. These preliminary results indicate the potential for anaerobic digesters to significantly decrease CH4 mole fractions observed from manure management. We also estimated CH4 emissions using a dispersion model and estimated the efficiency of the digester using CH4 fluxes measured at vents and biogas generation data. These results provide a quantitative estimate of CH4 emission reductions with anaerobic digesters, variation with seasonal meteorology, and point to where CH4 leaks may occur in these systems.