The anaerobic digestion (AD) sector continues to face a challenging development pathway, with ongoing delays to key policies needed to make the sector viable. Despite this, developers are actively progressing projects through the planning and licensing system so they are ready to go when the time comes. So far in 2025, there has been a surge of activity in the AD space, much of it linked to Nephin Renewable Gas (NRG).
Launched in 2024, NRG set out to become Ireland’s leading AD developer, with Irish farmers playing a central role in its plans.
Headquartered in Tipperary, NRG stated that it aimed to develop up to 20 large-scale AD plants across the country, with the goal of supplying one-fifth of the biomethane required by 2030.
The company said these projects will create hundreds of direct and indirect jobs throughout rural Ireland, open up new markets for farmers and support environmental and climate goals.
Since launching, the company has made a strong start, with four plants currently in the planning system and more expected to follow.
Backers
Nephin Energy is owned by Canada Pension Plan (CPP) Investments, a fund that had net assets in 2023 in excess of around €398bn. CPP Investments, which owns a 43.5% stake in the Corrib gas field off the coast of Mayo, supplies approximately 25% of Ireland’s natural gas. However, gas levels in the field have been steadily declining and are expected to be largely depleted within the next decade.
Arklow: decision pending.
In response, NRG was formed, which pulled together a seasoned team of AD developers and operators from Ireland and the UK and set to work in developing new AD plants.
Progress
There are currently four projects in the planning system, see figure 1, all following a standardised design and feedstock model. Further locations are yet to be announced. NRG stated that each location goes through a thorough assessment to determine its suitability. Its first project is in Ballinrobe, Mayo. After a significant request for further information, planning permission was granted earlier this month.
Working with 71 farmers in the area, the plant will require nearly 18,000t of cattle slurry, 9,500t of pig slurry, 12,000t of poultry manure, 20,000t of wholecrop silage and 5,000t of grass silage annually — most of it sourced within 5km of the site. Additional feedstock will include food waste, bringing the total to 90,000t.
Mitchelstown: further information requested.
A similar plant is in the planning system near Carrick-on-Suir, Waterford. Although granted permission by Waterford County Council, that decision has since been appealed to An Bord Pleanála. So far, 61 farmers within a 25km radius have agreed to supply feedstock and take back the resulting biofertiliser.
In Mitchelstown, Cork, the local authority has requested further information before making a decision. Meanwhile, the company’s latest project in Arklow, Wicklow, is due a decision next month.
Standardisation
The company has developed a standardised model for its projects, with only minor variations between them. This includes similar layouts, technology, capacity and feedstock. The plants are large, capable of handling up to 90,000t of feedstock to produce renewable biomethane gas, which will replace fossil natural gas. They will also produce liquid CO2 and treated digestate, which they refer to as a bio-based fertiliser.
The typical plant layout includes three digestion tanks, two digestate storage tanks, liquid storage tanks, liquid feed tanks, pasteurisation tanks and a post-pasteurisation cooling tank. It also includes a feedstock reception hall that accommodates a laboratory, panel room, tool store, workshop and general storage areas.
Plans also include a solid digestate storage and nutrient recovery building, as well as an odour abatement plant. Other key infrastructure includes a flare, gas upgrading equipment and an office and administration building.
All of the projects to date are proposing direct connections to the national gas grid.
Feedstock
Farmers will be offered contracts to supply a combination of cattle and pig slurry, poultry manure, wholecrop and grass silage, sourced within the vicinity of the plant.
It’s difficult to say what area of land will be needed to grow the crops, but potentially in the region of 1,500–2,000 acres per plant. No details have emerged yet on the proposed feedstock pricing structures, but silage and crops will only make up around 20–30% of the plant’s total feedstock. The plants will also source a combination of food production residues, drinks production residues and dairy production residues.
Digestate
The digestate will be returned to farmers. The plants will include a digestate treatment system which has a design capacity to treat around 78,000t of whole digestate per annum.
Following treatment of the whole digestate, around 8,000t of digestate fibre, and around 17,000t of liquid digestate concentrate will be produced. The treatment process will recover 53,000t of clean water, which will be reused on site for cleaning, with the remaining volume returned to the process as a feeding liquid.
Partnership
So far, the company has partnered with three landowners on their projects. In Ballinrobe one of these partners is John Sheridan, a farmer who owns and manages an intensive pig breeding and fattening facility. He owns the majority of the land around the site boundary, and his farm is close to the proposed AD plant. Nephin states that he will be a key supplier of feedstock to the plant.
In Carrick-on-Suir, Nephin has partnered with pig farmer James Foran, who runs a large-scale pig farm adjacent to the proposed site. The proximity of the pig farm was an important factor in selecting the location, as it allows for the immediate integration of animal slurry into the AD plant, Nephin has said.
In Arklow, Nephin has partnered with Seoirse McGrath, who owns and manages a dairy farm located just 100 metres from the site. The farm has been in the family’s ownership since at least 1761, and the McGrath family were the overall winners of the Glanbia Quality Milk Awards in 2007.
Community engagement
Rather than holding public consultation events, Nephin is going door to door to neighbours in the vicinity of each site to explain the projects and outline their plans. In Mayo, just two objections were received, mainly relating to public consultation and biodiversity. The Mitchelstown project attracted just under 10 objections, with concerns focused on the plant’s proximity to houses, zoning, health and safety and traffic.
The Carrick-on-Suir plant received just over 20 submissions and objections, with issues raised around biodiversity, traffic, proximity to houses and odour among others. After receiving the green light from Waterford County Council, that project was appealed by a group of 11 local residents. The appeal was comprehensive, running to 94 pages.
Nephin Energy support charitable and community organisations and have said that, in due course, once a plant is operational, a community support programme will be developed.
The author Stephen Robb is currently involved in a family/community proposal for an anaerobic digestion facility in Co Donegal.
The anaerobic digestion (AD) sector continues to face a challenging development pathway, with ongoing delays to key policies needed to make the sector viable. Despite this, developers are actively progressing projects through the planning and licensing system so they are ready to go when the time comes. So far in 2025, there has been a surge of activity in the AD space, much of it linked to Nephin Renewable Gas (NRG).
Launched in 2024, NRG set out to become Ireland’s leading AD developer, with Irish farmers playing a central role in its plans.
Headquartered in Tipperary, NRG stated that it aimed to develop up to 20 large-scale AD plants across the country, with the goal of supplying one-fifth of the biomethane required by 2030.
The company said these projects will create hundreds of direct and indirect jobs throughout rural Ireland, open up new markets for farmers and support environmental and climate goals.
Since launching, the company has made a strong start, with four plants currently in the planning system and more expected to follow.
Backers
Nephin Energy is owned by Canada Pension Plan (CPP) Investments, a fund that had net assets in 2023 in excess of around €398bn. CPP Investments, which owns a 43.5% stake in the Corrib gas field off the coast of Mayo, supplies approximately 25% of Ireland’s natural gas. However, gas levels in the field have been steadily declining and are expected to be largely depleted within the next decade.
Arklow: decision pending.
In response, NRG was formed, which pulled together a seasoned team of AD developers and operators from Ireland and the UK and set to work in developing new AD plants.
Progress
There are currently four projects in the planning system, see figure 1, all following a standardised design and feedstock model. Further locations are yet to be announced. NRG stated that each location goes through a thorough assessment to determine its suitability. Its first project is in Ballinrobe, Mayo. After a significant request for further information, planning permission was granted earlier this month.
Working with 71 farmers in the area, the plant will require nearly 18,000t of cattle slurry, 9,500t of pig slurry, 12,000t of poultry manure, 20,000t of wholecrop silage and 5,000t of grass silage annually — most of it sourced within 5km of the site. Additional feedstock will include food waste, bringing the total to 90,000t.
Mitchelstown: further information requested.
A similar plant is in the planning system near Carrick-on-Suir, Waterford. Although granted permission by Waterford County Council, that decision has since been appealed to An Bord Pleanála. So far, 61 farmers within a 25km radius have agreed to supply feedstock and take back the resulting biofertiliser.
In Mitchelstown, Cork, the local authority has requested further information before making a decision. Meanwhile, the company’s latest project in Arklow, Wicklow, is due a decision next month.
Standardisation
The company has developed a standardised model for its projects, with only minor variations between them. This includes similar layouts, technology, capacity and feedstock. The plants are large, capable of handling up to 90,000t of feedstock to produce renewable biomethane gas, which will replace fossil natural gas. They will also produce liquid CO2 and treated digestate, which they refer to as a bio-based fertiliser.
The typical plant layout includes three digestion tanks, two digestate storage tanks, liquid storage tanks, liquid feed tanks, pasteurisation tanks and a post-pasteurisation cooling tank. It also includes a feedstock reception hall that accommodates a laboratory, panel room, tool store, workshop and general storage areas.
Plans also include a solid digestate storage and nutrient recovery building, as well as an odour abatement plant. Other key infrastructure includes a flare, gas upgrading equipment and an office and administration building.
All of the projects to date are proposing direct connections to the national gas grid.
Feedstock
Farmers will be offered contracts to supply a combination of cattle and pig slurry, poultry manure, wholecrop and grass silage, sourced within the vicinity of the plant.
It’s difficult to say what area of land will be needed to grow the crops, but potentially in the region of 1,500–2,000 acres per plant. No details have emerged yet on the proposed feedstock pricing structures, but silage and crops will only make up around 20–30% of the plant’s total feedstock. The plants will also source a combination of food production residues, drinks production residues and dairy production residues.
Digestate
The digestate will be returned to farmers. The plants will include a digestate treatment system which has a design capacity to treat around 78,000t of whole digestate per annum.
Following treatment of the whole digestate, around 8,000t of digestate fibre, and around 17,000t of liquid digestate concentrate will be produced. The treatment process will recover 53,000t of clean water, which will be reused on site for cleaning, with the remaining volume returned to the process as a feeding liquid.
Partnership
So far, the company has partnered with three landowners on their projects. In Ballinrobe one of these partners is John Sheridan, a farmer who owns and manages an intensive pig breeding and fattening facility. He owns the majority of the land around the site boundary, and his farm is close to the proposed AD plant. Nephin states that he will be a key supplier of feedstock to the plant.
In Carrick-on-Suir, Nephin has partnered with pig farmer James Foran, who runs a large-scale pig farm adjacent to the proposed site. The proximity of the pig farm was an important factor in selecting the location, as it allows for the immediate integration of animal slurry into the AD plant, Nephin has said.
In Arklow, Nephin has partnered with Seoirse McGrath, who owns and manages a dairy farm located just 100 metres from the site. The farm has been in the family’s ownership since at least 1761, and the McGrath family were the overall winners of the Glanbia Quality Milk Awards in 2007.
Community engagement
Rather than holding public consultation events, Nephin is going door to door to neighbours in the vicinity of each site to explain the projects and outline their plans. In Mayo, just two objections were received, mainly relating to public consultation and biodiversity. The Mitchelstown project attracted just under 10 objections, with concerns focused on the plant’s proximity to houses, zoning, health and safety and traffic.
The Carrick-on-Suir plant received just over 20 submissions and objections, with issues raised around biodiversity, traffic, proximity to houses and odour among others. After receiving the green light from Waterford County Council, that project was appealed by a group of 11 local residents. The appeal was comprehensive, running to 94 pages.
Nephin Energy support charitable and community organisations and have said that, in due course, once a plant is operational, a community support programme will be developed.
The author Stephen Robb is currently involved in a family/community proposal for an anaerobic digestion facility in Co Donegal.
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