Farm Ireland

Saturday 24 March 2018

'Green' gas plan will pay farmers to offload waste

Anaerobic digester
Anaerobic digester

Farmers could be paid to dispose of agricultural slurry and organic waste under plans to ramp up production of renewable gas.

Gas Networks Ireland (GNI) says as much as 10,000 GWh of gas - around 20pc of annual demand - could be produced from agricultural waste and grass which would help Ireland meet ambitious renewables targets.

Large industrial energy users are increasingly demanding 'green' gas to power their facilities, Ian Kilgallon from GNI said. He added there was an abundant source of raw feedstock available, and ramping up production would not require major investment in new infrastructure.

Around 50 locations across the network had been identified as suitable 'injection' sites, of which around 12 would be required and cost between €1.5m to €3m each to develop.

He also said a network of between 100 and 200 smaller co-operative facilities would be needed, where gas was produced before being compressed and transported by road to an injection point.

"The industry is demanding green", Mr Kilgallon said.

"Ireland has abundant sustainable sources of renewable gas to meet the demands of industry. The existing natural gas network can facilitate the supply of renewable gas to industry and provide energy security through access to a European-wide green gas market."

However, Barry Caslin, bioenergy specialist with Teagasc , said while green gas was a viable option, the feed-in tariff would have to be increased.

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It currently stands at 15 cent per kilowatt (kWh) produced, which was not sufficient to make investment attractive.

"It's viable for Ireland, and the technology is well proven. It hits the targets for heat, transport and electricity. You can generate electricity and heat for a local school or library, and that's the ideal way it should be working.


"If you take grass silage, you can get 250 kWh from a tonne. If it was costing €25 per tonne, it would be 0.10 cent per kWh. The operational and maintenance cost is 2c to 3c per kWh. For every kWh it's costing you 13c, but you're only getting 15c. The tariff needs to be higher."

He also said that slurry manure from pig and poultry units would be suitable, or for large dairy farmers, if mixed with food waste.

He said there were 40 anaerobic digestors in Northern Ireland, because the feed-in tariffs were almost double that in the Republic.

GNI has some 13,500kms of pipeline, and more than 675,000 gas customers, including 25,000 businesses which are increasingly focusing on renewables.

Renewable gas would also help large energy users meet a target to produce 12pc of their heating needs from renewable sources by 2020, and help meet a transport target of 10pc.

The plan would also remove the need to burn so much fossil fuels, which are the primary source of greenhouse gas emissions which drive climate change.

"There would also be diversification of family farm incomes," Mr Kilgallon said. However, a feed-in tariff would be required to encourage investment. This would comprise a state payment to producers, and not until that is in place will a fee per tonne of feedstock be decided.

Renewable gas is produced by anaerobic digestion, where the waste is fermented in an oxygen-free environment and gas formed.

Two other methods are also used, including gasification where the feed stock is broken down and gas forms, which is purified and cooled, and power-to-gas technologies.

The feedstock is organic waste and slurries, agricultural slurries and additional grass, not required for livestock. Agricultural food processing residues, waste water treatment residues and animal manures could also be used.

Current state supports are exclusively for renewable electricity, and funding would have to be in place for renewable gas and the plants required.

State support schemes are in place across EU countries including the UK, the Netherlands, Germany and Finland, to incentivise investment.

Around 10,000 GWh of renewable gas could be produced every year. We currently use some 53,000 GWh.

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