The economic case for the production of silage for Anaerobic Digestion (AD) can only be established by analysis of the potential costs and returns at farm level. This paper uses farm level data from Ireland in a bio-economic modelling framework to provide total costs per hectare and per tonne for production of silage for an off farm AD facility. Whilst perennial rye grass has traditionally been the sward of choice for livestock farmers in Ireland, the economics of a multi-cut nitrogen fixing crop such as red clover has been relatively unknown. The results from the simulated bio-economic model show that the total costs of production silage for AD has increased significantly in the past twenty four months. The modelled cost of Red-Clover based silage fertilised with digestate has increased from €29.35 to €43.68 per ton between 2018-2020 to 2022, an increase of 49%. The results also highlight the importance of accounting for the opportunity cost of nutrient content of digestate which increased from €370 to €907 between 2018-2020 and 2022. Furthermore, a 17% cost saving can be made while reducing overall GHG emissions by utilising digestate in a separate farm enterprise.