To ask the Minister of Agriculture, Environment and Rural Affairs (i) how many anaerobic digestors in Northern Ireland utilise bio-methane as a resource for the natural gas market; and (ii) for his assessment of the utilisation of bio-methane from anaerobic digestors as a means to reduce Northern Ireland’s carbon emissions.

(i) There are approximately 70 anaerobic digesters in Northern Ireland currently operating and generating biogas. The biogas produced is usually fed to engines for microgeneration on-site to produce electricity which is either used onsite or fed to the grid. The rural locations of most of these anaerobic digesters are remote from the gas network. Therefore, the number currently producing bio-methane as a resource for the natural gas market is likely to be low. A Committee for Climate Change (CCC) report in 2019 stated the less-developed gas network in Northern Ireland means that bio-methane injection to the grid may be more difficult, and anaerobic digestion may be limited to space and process heating or Combined Heat and Power (CHP) microgeneration on-site in locations without easy access to grid injection points.

(ii) Bio-methane from anaerobic digesters is already reducing Northern Ireland’s carbon emissions by offsetting the use of fossil fuels (coal and oil) to produce electricity and heat, although this is likely a modest offset compared to other types of renewable energy generation. Biogas from anaerobic digesters is generally of a lower quality than imported natural gas and needs to be processed/purified to upgrade it to bio-methane.

There is potential to utilise bio-methane to displace natural gas for heat production and to potentially expand the anaerobic digester industry in Northern Ireland to increase supply. This would have a positive impact on reducing carbon emissions but is likely to require an incentivised scheme for electricity or heat production to make it economically viable due to the high capital expenditure associated with plant construction.

Environmental impacts of expanding the anaerobic digester sector on water quality, air quality and potentially on sensitive habitats would also have to be considered.