Teagasc today, December 11th, announced the publication of a landmark research report assessing the potential for agriculture-based anaerobic digestion (AD) to support Ireland’s growing biomethane industry. This research project was jointly funded by the Sustainable Energy Authority of Ireland (SEAI) and Gas Networks Ireland (GNI) through the SEAI National Energy RD&D Programme, grant number 19/RDD/493.
The report, produced under the FLEET Project (Farm Level Economic, Environmental and Transport Modelling of Alternative Feedstocks for Regional Anaerobic Digestion), delivers the most comprehensive assessment to date of the economic viability, environmental impact, and logistical challenges involved in using grass and animal waste as a feedstock for biomethane production at a national scale.
The report finds that while supplying grass silage to AD plants can be a competitive alternative to traditional cattle and sheep enterprises, profitability varies significantly by farm and depends heavily on the price paid to farmers for silage.
A survey conducted as part of the study revealed a strong willingness among farmers to supply 175,000 hectares of silage, well above the 110,000 to 130,000 hectares estimated to be required to meet Ireland’s 5.7 TWh biomethane production target for 2030.
The study also highlights significant environmental benefits to increased AD adoption. Grass-based AD feedstock systems could reduce farm-level greenhouse gas (GHG) emissions by 50 to 98% per hectare on participating farms, driven largely by reductions in livestock numbers. Slurry-based AD feedstock systems were found to deliver emissions reductions as high as 11% per hectare.
A spatial transport analysis included in the study using national road network data indicates that, under non-constrained typical conditions, most AD feedstocks could be sourced within 10 km of potential AD plant locations. Under more constrained conditions, this range could extend to 15 km or more, with implications for both the associated cost and the emissions reductions achieved.
At the national level, the development of a biomethane industry using grass silage and animal slurry to meet the 2030 target is projected to increase agricultural sector income by 1.2% to 1.3% (€49–€53 million) and reduce agricultural GHG emissions by 2.3% compared with a scenario where such feedstock use does not occur.
With the publication of the final FLEET report, Teagasc and project partners will continue to advance research in this area. Future work will assess additional feedstocks, explore alternative business models, and update economic and environmental analyses in line with evolving market and policy conditions.
The final report can be accessed at: https://teagasc.ie/wp-content/uploads/uploads/media/website/publications/2025/Farm-Level-Economic-Environmental-and-Transport.pdf