There is significant interest to develop an anaerobic digestion (AD) industry to produce biomethane in nearly all counties of Ireland, according to a new report.

In October 2022, Gas Networks Ireland (GNI) issued a request for information (RFI) to prospective biomethane producers to help identify new and feasible biomethane projects.

GNI received 176 responses from interested developers who intended to produce 14.8TWh (terawatt hours) of biomethane annually, surpassing the 2030 Climate Action Plan goal of 5.7TWh. This could replace 26% of Ireland’s natural gas.

Around 60% of developers aimed to produce 40-55GWh (gigawatt hours) of biomethane annually from their AD plants.

To put this in perspective, a 40GWh agricultural AD plant would need about 2,000ac of grass silage and 25,000t to 30,000t of slurry as feedstock, with an estimated construction cost of approximately €15m.

The RFI responses show that around 80% of the required AD feedstock is expected to come from agricultural sources.

Around 38% of this would be slurry, 28% grass silage and mixed-species swards and 14% from various other crops

If the RFI production figure was realised, this would result in an approximate annual emissions saving of 3.94Mt CO2 equivalent or 16% of agriculture’s total emissions.

Respondents from Monaghan, Kildare and Limerick were the counties with the highest level of biomethane production intention, respectively.