Anaerobic Digestion

Local and National Policymakers, Local Businesses, Local Farmers

Courtesy: Peter O'Connor aka anem... (Flickr)
Courtesy: Peter O’Connor aka anem… (Flickr)

Anaerobic digestion is the process which involves the breakdown of organic material by bacteria in an oxygen-free environment to create biogas. Farm, municipal and industrial based plants convert waste material into biogas. Agricultural wastes (e.g. animal slurry), silage, sewage sludge, food/canteen waste, garden waste, waste vegetable oils and certain industrial waste are the most common feedstocks used. Waste material is fed into a digester which contains bacteria. The digester is a closed container and contains zero oxygen. The biogas produced can be used for heat and power and the process residue can then be used as a fertiliser.

Currently, there are only about six anaerobic digestion plants in the Republic of Ireland, mostly in the south and south-east of the country. This is compared with 26 in Northern Ireland. Some of the reasons for the low level of plants in the Republic include a complex planning and licensing system with 8 different permissions required, grid connection costs, unattractive electricity tariffs, financing issues and uncertainty in waste policy. This is a technology that could be adopted in Galway to help us tackle our waste, create biogas and fertiliser as well as create jobs. See also ‘Biogas’ in the Energy chapter for further information.
Cré (The Composting and Anaerobic Digestion Association of Ireland), Enfield, Co. Meath
Bioenergy Proliferation and Deployment