Thursday, 21 April 2022 | 11.6°C Dublin
I reland is behind the curve with a renewable energy source that can be made relatively cheaply from feedstock on our farms, but there is an opportunity to catch up
Opportunity: A report commissioned by Gas Networks Ireland suggested that biomethane can be delivered sustainably and at scale in Ireland. Photo: Leo Gomes
The biggest opportunity for biomethane is its deployment where there are no other viable decarbonisation options
High energy and fuel prices, unprecedented pressure on agriculture to cut emissions and farmers scrabbling for alternatives to chemical fertiliser as prices soar…
A ll these ingredients should be driving a surge in interest in anaerobic digestion for the production of biomethane, yet Ireland has not embraced it.
That may be about to change. Last year the Government included the roll-out of sustainable anaerobic digestion or biomethane in the Climate Action Plan.
A major dairy industry collaboration, led by Danone, has declared its commitment to large-scale biomethane production on Irish farms.
Further, in October, a report commissioned by Gas Networks Ireland suggested that biomethane can be delivered sustainably and at scale in Ireland.
The report carried out by Devenish and KPMG found there is sufficient capacity from improved efficiency across land already in agricultural production to supply up 15pc of Ireland’s industrial gas.
On a recent Teagasc webinar discussing the report, Russell Smyth of KPMG said anaerobic digestion (AD) is now “considered a proven technology” and explained that Ireland is behind the curve.
“Northern Ireland has over 90 AD plants deployed. Across Germany, France, Denmark, there are thousands. A lot of jurisdictions have mobilised and are mobilising at pace on this. Ireland to date has been very hesitant on this technology.”
He said a number of environmental and economic concerns have hampered its development in Ireland.
For Smyth, the key question is, can sufficient extra feedstock be produced to supply a biomethane industry without impacting current food production systems?
The answer is yes, according to Devenish research at their farm in Dowth, Co Meath. This concluded that by improving soil fertility and using multi-species swards — which require less chemical nitrogen — more grass can be grown on many Irish farms, which could be used as feedstock for anaerobic digestion plants.
It also estimated that 768,000ha of land is available and suitable to grow feedstock for a biomethane industry.
This land bank is primarily used for beef cattle grazing or beef sector silage production, which has not been optimised for land fertility or crop yield. The area excludes High Nature Value (HNV) areas and grassland devoted to dairy.
The report found that Ireland has both the technical capacity and capability to produce an additional 5pc of feedstock to supply an indigenous biomethane industry.
In total, it has been calculated that Ireland could produce an additional 3.1m tnDM of feedstock from improved efficiency across land already in agricultural production without impacting feedstock.
“Biomethane in Ireland will not happen if it is eating into feedstock availability for cattle. Therefore, it is all about producing incremental feedstock,” Smyth said.
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“Ireland does have sufficient capacity in our analysis to produce the incremental feedstock to support a good-sized level of biomethane production.”
However, he warned that there is no point in developing a biomethane industry in Ireland to solve an environmental challenge if it actually results in the overall emissions in agriculture increasing.
“It has to be done in a way which does not increase emissions or the use of chemicals or other fertilisers in the sector,” he said.
Here too, Smyth said research has shown that additional grass can be grown on farm without increasing emissions.
Based on the research at Dowth, there would be a short-term increase in fertiliser applications as landowners build and optimise soil fertility, but once the initial deficit is addressed, it is possible to operate the land with materially lower carbon inputs, while producing significantly enhanced yields, resulting in a reduced overall carbon lifecycle on the land.
This, the researchers said, was because fewer artificial inputs would be needed, as nutrients coming from the AD plant would displace inorganic fertilisers and bring down the carbon footprint.
It was highlighted that after year one, 100pc of the nitrogen requirement would be supplied through the slurry digestate.
The report concluded that Ireland has the ability to produce 2.5 terawatts of biomethane by 2030. That would see around 125 individual farm-scale AD plants producing 20 gigawatt-hours each, accounting for around 15pc of the industrial and commercial gas used in the country.
“Biomethane is always going to be in short supply, and we’re never going to have enough to displace everything we’d love it for. So it’s about using it in a targeted way,” Smyth said, adding that the biggest opportunity for biomethane is its deployment where there are no other viable decarbonisation options.
The biggest opportunity for biomethane is its deployment where there are no other viable decarbonisation options
“The sectors that have been identified are high thermal temperature users — for example, the milk drying sector uses an awful lot of natural gas at very high temperatures. It’s about directing the limited amount of biomethane to those sectors that have no other options,” he said.
In terms of the ability of biomethane production to contribute to farm income, Smyth said that while profitable dairy farmers were unlikely to see benefits, the average beef farmer would see a better economic return.
“At current gas prices, biomethane is relatively cheap and you’d have a very economic AD plant, without question,” he said. “However, I don’t think in the long term that gas prices will stay at this elevated level.
“Ireland does not have any subsidy for the gas. The Government is likely to announce fairly shortly a renewable heat obligation scheme. That would put an obligation on any large thermal energy suppliers to produce or purchase a proportion of their gas from renewable sources such as biomethane.
“That will provide a statutory demand for biomethane. If those suppliers don’t purchase the gas, they’ll have to pay a fine, which will underpin a value for biomethane.”
A roll-out model for biomethane in Ireland has been developed a number of Irish agri-food companies.
The plan, known as Project Clover, assumes the roll-out of 125 x 20 GWh farm-scale biomethane AD plants by 2030, fed primarily on agricultural materials and farm wastes.
2.5TWh biomethane would be produced by 2030, requiring 125,000ac of agricultural land (1.1pc of Ireland’s agricultural land base) to produce the required 2.6m (wet) tonnes of plant-based feedstock (5pc of the current volume of grass silage produced annually in Ireland), alongside 1.75m tonnes of slurry (4pc of the current volume).
The volume of biomethane gas produced under this model would be sufficient to displace 15pc of current commercial and industrial natural gas consumption.
The plants would be primarily connected through a remote virtual pipeline of compressed gas tankers transporting biomethane from rural AD locations to centralised grid injection points, although there is scope for larger plants (40 GWh and up) to have a direct injection into the grid.
To deliver the volume of feedstock required under the deployment model, Ireland would need to see around 20pc of the 768k ha landbank identified as suitable land adopting land improvement techniques over the coming decade.
Russell Smyth of KPMG said the average ad plant would need 1,000ac of land to feed it with multi-species swards or grass silage.
“This is likely to be an AD plant located on a farm supported by feedstock coming in from a number of farms,” he said.
“There’s an optimum size, and we think it’s 20GWh, which gets you some economies of scale, but also allows you to source feedstock from a reasonable distance. We wouldn’t want to be bringing grass silage more than 10km and slurry more than 3-4km.”
In terms of ownership, Smyth said a model where a number of farmers come together to invest in an AD is the most suitable.
“The first farm-scale AD plant I raised funding for was three individual farmers in Cookstown in Northern Ireland — a beef farmer, a sheep farmer and dairy farmer,” he said.
“The three of them came together, and between them, they had enough land and enough slurry. They built it on a piece of land owned by one of them that was fairly central, and the three of them owned a third of it.”
Northern Ireland developed around 90 AD plants between 2011 and 2017, despite a slow initial uptake of the technology in comparison to the rest of the UK.
However, the reduction of the financial support schemes in Britain, along with sustained support from the Northern Ireland schemes, and the high availability of feedstocks, made the North the most attractive region in the UK for AD investment. While financial support for ADs in Northern Ireland is limited, previously, financial support has come from Government schemes as well as commercial loans.
The NIRHI scheme was introduced in 2012 and offered a tariff for biogas boiler or CHP heating systems. The scheme was subject to a public inquiry (2017-20) after concerns were raised over the potential costs of delivery for the scheme’s lifecycle (20 years).
It was recommended it be closed and replaced by a scheme that “effectively cuts carbon emissions”. The scheme closed for new applications in 2016.
Smyth said there were initial fears that biogas production would fundamentally disrupt the agricultural system in the North.
However, he said that despite the plants consuming 700,000t of grass silage annually (8pc of historic silage production), over the same period, the number of dairy cattle grew by 12pc, while overall cattle numbers increased by 4pc.
“We’re not looking to compete for the same grass that’s currently going into dairy system or into the beef system and convert it to AD,” he said. “The model we’re promoting is about incremental feedstock production.
“Loads of Northern Irish farmers were able to double the amount of grass silage they were growing without doing anything particularly radical. They just never had a need for more grass silage. They produced just enough for their cattle.
“When they tried, they were able to substantially increase the volume. And that’s what this is about. It will not work if we’re redirecting the grass silage away from cattle and we’re competing for the same feed.”
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