With Ireland about to exceed its greenhouse gas emissions limit agreed under the Kyoto protocol, an effective way of tackling the problem has been suggested - a system called " anaerobic digestion". It could help not only to reduce such emissions but to provide a valuable opportunity for additional income on small farms, according to an international scientific conference in Galway earlier this month. If just over 25 per cent of the animal slurries and manures already collected was processed by anaerobic digestion, more than 100 megawatts of electricity and a similar quantity of heat could be generated - equivalent to 200 million litres of diesel.
Government policies are inhibiting the application of the process here, the conference was told.
Anaerobic digestion involves the use of naturally occurring bacteria to break down organic matter in the absence of oxygen. It emits biogas, which can be used to provide energy - similar to natural gas. The processed material is a homogenous liquid that is almost odourless and is a valuable liquid fertiliser.
The two-day conference, which was organised by NUI Galway's department of microbiology on behalf of two EU-funded organisations, AD-Nett and EfW (Energy from Waste Network), was attended by more than 100 people from 20 countries, including experts in anaerobic digestion, operators of large and small plants, legislators, design and service industry representatives, developers and representatives of the farming and food processing sectors. The Danish government, for instance, has pursued an interdepartmental policy of support for biogas plants over the past 12 years. This has resulted in 20 centralised anaerobic digestion plants, co-operatively owned by farmers, which provide electricity for a district heating network, and liquid fertiliser.
The use of the liquid fertiliser has reduced the use of artificial fertiliser, with a consequent positive effect on rivers that were previously exposed to pollution.
In Germany, a farmer can use the biogas from his plant to produce electricity, and get a reasonable price for it.
More than 400 small biogas plants have been installed there in the past two to three years, with the additional income helping small farmers to stay in business. In Holland, there are similar incentives, and Italian pig producers are encouraged to use the process to treat slurry and control odours.
Ireland has only five farm plants and two or three centralised plants are being planned. Given that anaerobic digestion could help to assist the waste management, sustainable energy and anti-pollution strategies that the Government is trying to implement, there should be far more official support for it here, the conference heard.