Dr. Ciara Beausang:

The SEAI study, in terms of the feedstock resource, is sensitive to the need to produce grass silage in a sustainable way so it does take into account the potential of digestate for the production of grass silage. Regarding methane leakage, the report acknowledges that there will be a small amount lost in biogas production but does not specify the figure that is assumed in the analysis. I have tried to clarify that with SEAI. It would be useful to know its assumption in terms of average methane loss.

Continuing on the SEAI heat study, there is good analysis of the resource availability of grass silage and slurry, looking at areas of 5 sq. km. There is a distinction between looking at a catchment area of 10 km to collect the feedstock to supply a biogas plant, and a wider area of 20 km. That is also considered in the report. It is worth considering sensitivity analysis to see if there is a difference in extending that transport distance for the feedstock. For something like slurry, which is low density and has a low energy potential, ideally we want to restrict the distance it is transported and 10 km would be ideal. For grass silage, there may be potential to extend the distance but it would be good to look at the distinction between those two transport distances.