A techno-economic analysis of small-scale farm-based anaerobic digestion plants in an irish dairy farm context

Ireland has committed itself to a 20% reduction in greenhouse gas (GHG) emissions by 2020 compared to a 2005 baseline. Based on current trends, Ireland is projected to miss this target with a reduction of only 4% to 6% (EPA, 2017). The agriculture sector has been identified as the single largest contributor, producing 32.3% of the total emissions produced in 2016. Small-scale anaerobic digestion (SSAD) holds promise as an attractive technology for the treatment of livestock manure and the organic fraction of municipal wastes, especially in low population communities or standalone waste treatment facilities. SSAD is particularly applicable to the Irish agriculture sector where the average dairy herd size consists of approximately 80 cows in 2016. Despite the apparent benefits of SSAD the technology is still not well understood with much of the research previously conducted focused on large-scale systems. To assess the viability of SSAD in Ireland, this study examines the technical, economic and environmental considerations of constructing and operating SSAD plant’s on commercial Irish dairy farms.