11.6.7 Renewable Gas Anaerobic Digestion (Biomethane)
11.6.7 Renewable Gas Anaerobic Digestion (Biomethane )
The process of Anaerobic Digestion (AD) involves the breakdown of organic matter by bacteria and enzymes in an oxygen-free environment. The end product of this process is biogas which is a gas with a high methane content. This methane can be captured and burned to produce heat, electricity or a combination of the two. It is the policy of the Plan to encourage the development of such anaerobic digestion and renewable gas infrastructure in County Kilkenny.
Anaerobic Digestion is used widely in the agricultural sector in the form of small on-farm digesters producing biogas to heat farmhouses and other farm buildings. The main types of organic material feedstock used in AD are:
• sewage sludge
• farm slurry
• municipal solid waste (MSW)
An Anaerobic Digestion plant typically comprises of:
- a digester tank
- buildings to house ancillary equipment such as a generator, a biogas storage tank
- a flare stack (3-10m in height)
- associated pipework.
Plants can vary in scale from small schemes treating the waste from an individual farm through medium-sized centralised facilities dealing with wastes from several farms (potentially supplemented by crops such as maize grown specifically to feed the digester) to sizeable industrial AD plant handling large quantities of municipal solid waste. In the case of small plants it is likely that the plant can be accommodated within the vicinity of existing farm buildings. Some forms of biomass produce digestate and other end products which must be disposed of.
The Camphill community in Ballytobin uses an anaerobic digester which performs centralised co-digestion of farm slurry with mixed food waste. This generates energy (heat and power) to meet the requirements of the 90 people living in Ballytobin Camphill Community.
Permission was granted (P.12/354) for an anaerobic digestor at a piggery in Piltown.
The 3 Counties Energy Agency are working through the gas innovation fund 2020 to identify the renewable gas resource potential in Co . Kilkenny within the South East Region. The findings of this report in 2021 will support the locating of grid gas injection points strategically located around the region to make this gas available to meet the fossil gas demands in the urban centres of the counties.