Silage may hold key to heating homes

UP TO 300,000 Irish homes could be heated by renewable gas within the next 10 years through a network of biomethane plants using…

UP TO 300,000 Irish homes could be heated by renewable gas within the next 10 years through a network of biomethane plants using silage and slurry in a €1.4 billion investment, a new report has found.

The report, commissioned by Bord Gáis and carried out by the Environmental Research Institute in UCC and Ernst and Young, has found Ireland could obtain 7.5 per cent of its natural gas needs by 2020 through the development of renewable gas projects.

The Future of Renewable Gas in Irelandreport envisages the creation of almost 200 anaerobic digesters to convert silage, slurry and waste from meat plants, as well as organic municipal waste to generate biomethane.

According to the report, Ireland would need 183 rural anaerobic digesters at a cost of €7 million per plant, located in rural areas with each processing some 29,000 tonnes of silage and 21,000 tonnes of slurry to generate 390 million cubic metres of biomethane a year.

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This would give an overall cost of €1.28 billion, while a further four larger plants at slaughter houses would cost another €60 million.

Four larger plants to cater for organic municipal waste would cost another €80 million.

According to Bord Gáis chief executive John Mullins, “capturing this renewable gas resource would be a considerable step in addressing Ireland’s challenging renewable energy and waste management objectives.

It would also help reduce our dependence on energy imports, provide jobs in the construction and operation of biomethane plants and create new business opportunities among the farming community in rural Ireland.”

Mr Mullins said each rural plant would require some 530 hectares of cut grass a year to supply and he suggested farmers could work together in groups of between 30 and 100 to supply the digesters.

It was now possible for this biomethane gas to be directly fed into the Bord Gáis network, but in rural areas not serviced by the network it would be possible to tap the gas and use it to run buses and trucks as happens in many regions across Europe, he said.

Dr Jerry Murphy, principal investigator in bioenergy and biofuels at the Environmental Research Institute in UCC, said it would be possible to run all 89 buses that currently operate in Cork on biomethane created from 600 hectares of harvested grass annually.