One of Ireland’s most advanced anaerobic digestion (AD) plants could soon be located at Killough Quarry, Tipperary. Roadstone is seeking planning permission to build an AD plant on a 15ac site that will produce biomethane gas to decarbonise operations at the quarry, with plans to roll out three more plants at other sites in the coming years.
The company last week held its second public consultation to answer questions and listen to concerns from residents. There has been significant kickback to the proposals from the local community, with issues raised including traffic volumes, odour, potential explosion risk, water contamination and the impact on property values.
The Irish Farmers Journal attended the drop-in information event at the Horse and Jockey Hotel and spoke to developers, partners and concerned members of the community.
Not your average plant
If built, the AD plant may be amongst the most advanced in Europe and more akin to a food-processing facility than a traditional AD plant. Rather than conventional tanks and domes, known as a continuously stirred tank reactor (CSTR) system, the plant will use the Norwegian-developed Antec system.
The Antec system uses plug-flow AD reactors.
The Antec system uses plug-flow AD reactors, essentially large, sealed, rotating cylinders instead of conventional tanks. The cylinders are housed inside a building on the site.
John Jones, CEO of Utopia, which develops and operates integrated circular economy bioenergy parks and has partnered with Roadstone in Killough, said the Antec system is very different.
It significantly speeds up biogas production and will reduce conventional digestion times from around 50-60 days to nine days, on a much smaller footprint. The system operates at thermophilic temperatures of 55°C. The Killough plant will have 30 Antec reactors and will be the first of its kind in Ireland. Currently, there are eight plants of this kind operational in Norway. The Killough plant is based on the Vest Biogass plant in Norway.
Feedstock
The plant will be agri-based, requiring around 15,000t of chicken manure, 20,000t of cattle slurry, 60,000t of grass silage, 5,000t of maize silage and 5,000t of pot ale and spent grain annually as feedstock.
Climaticus director Maurice Deasy, who is assisting with communications and feedstock supply for the project, explained that feedstock terms, contracts and pricing arrangements have not yet been developed and will be co-developed with farmers. Feedstock would be sourced from farms within a 60km radius of the plant.
The plant will be agri-based.
The plant will pre-process its feedstock. An acoustic cavitation process will be used to break down the plant cell structure of the grass and silage, allowing it to be digested quickly. Jones estimates this system will increase grass yields by around 30%.
Ammonia will be stripped from the chicken manure, allowing higher throughput than unprocessed manure. The processed material will then mixed with slurry to create a homogeneous “bio-soup”, which will be heated to the required temperature before entering the reactors.
Output
Jones described it not as a biogas plant, but as a decarbonisation asset. The facility will convert feedstocks into five co-products: liquid biomethane, liquid CO2, electricity, organic fertilisers and water.
Biogas will be separated into methane and CO2, with total biomethane production estimated at approximately 8,880,000 m³. The biomethane will be purified to 99.99% and cooled to minus 160°C, producing around 6,000 tonnes of bio-LNG annually. This replaces earlier plans to compress and export gas off-site. As there is no nearby gas pipeline, gas will not be exported to the national grid. Some energy will be used on site, with the remainder exported.
Electricity and heat will be generated using a solid oxide fuel cell rather than a conventional combined heat and power (CHP) plant.
Feedstock terms, contracts and pricing arrangements have not yet been developed.
The CO2 will be cleaned and liquified, with options being explored to sell it in Ireland or generate new fuels. Digestate will be separated into solid and liquid fractions, with solids dried and pelletised and liquids treated to recover water for reuse within the AD process, or for fire and dust suppression. Jones pointed out that no water will be discharged.
Why AD
Pat Gibney, planning and property officer with Roadstone, explained that the AD plant would play a key role in decarbonising the company’s operations. Killough Quarry currently hosts an asphalt plant, a concrete plant, a limestone processing facility and ongoing quarrying operations. Roadstone’s total energy use in Ireland amounts to around 360 gigawatt-hours, while the proposed plant would produce 85 gigawatt-hours.
The intention, he said, is that the biomethane gas produced from the plant would be used to replace diesel and liquid natural gas currently used in these operations, with surplus gas exported to other end users. He said Killough was chosen because they own the site, it has an existing high energy demand and it is central.
However, he said they did not expect the level of community opposition to the plant. He said he thinks they have explained the project as best they can, but that there is misinformation out there about the proposal.
Lack of information
However, Alice Coleman, a member of the Killough Biogas Concern Group, believes that communication around the project has been poor. Speaking to the Irish Farmers Journal during the drop-in event, she said they felt the community was not given a lot of information about the project.
She said that she wants to see a community meeting-style event rather than a drop-in style event, so they can ask questions in front of an audience and have the answers on record for everyone to hear.
Biogas will be separated into methane and CO2, with total biomethane production estimated at approximately 12,170,000m³
Location
A key issue for her is the location of the plant. She said that she and her neighbours do not oppose AD technology, but feel the proposal is in the wrong location.
She said that she lives 500m away from the site and there are six to seven houses very close to the site. She said that planning guidelines are non-existent for these developments, with no legal minimum setback from houses.
When asked where they believed the right location was, she said that it should be located in Lisheen, Thurles, Tipperary, 20km north, where there are currently three plants in operation or in development, as it will not be close to houses.
Water
Another key concern of the group is the risk to drinking water, citing the proximity to an aquifer and the risk of the AD plant leaking. When this was put to him at the information event, Jones insisted that the entire site is sealed, double-bunded and can hold upwards of 150% of the total volume of the plant.
Therefore, if there were a catastrophic leak, it would be contained within the bund. Roadstone have said they will install four groundwater monitoring wells at the site to monitor groundwater quality.
Traffic
There is significant concern about the volume of traffic the plant would generate and the condition of local roads. Roadstone stated that the quarry and its ancillary activities are already permitted for up to 235 HGV movements per day and committed that the proposed AD facility would not increase this figure.
Other concerns
Coleman also highlighted concerns around explosion risk, LNG safety, quarry blasting adjacent to an operational AD plant, odour and the lack of clear community benefit from the project.
When asked how Roadstone could address these concerns, she said there was little they could do, adding that members of the group are prepared to “go all the way”, including a potential judicial review.
Site visit
Jones explained that there has been community engagement and that he has offered to bring locals to see an operational plant in Norway. He said that so far, they have brought 30 to 40 people over to Norway to see the plant.
Gibney said that a decision is due on 7 February and, depending on the outcome, the plant could be operational by 2029.
The author Stephen Robb is currently involved in a family/community proposal for an anaerobic digestion facility in Co Donegal.
One of Ireland’s most advanced anaerobic digestion (AD) plants could soon be located at Killough Quarry, Tipperary. Roadstone is seeking planning permission to build an AD plant on a 15ac site that will produce biomethane gas to decarbonise operations at the quarry, with plans to roll out three more plants at other sites in the coming years.
The company last week held its second public consultation to answer questions and listen to concerns from residents. There has been significant kickback to the proposals from the local community, with issues raised including traffic volumes, odour, potential explosion risk, water contamination and the impact on property values.
The Irish Farmers Journal attended the drop-in information event at the Horse and Jockey Hotel and spoke to developers, partners and concerned members of the community.
Not your average plant
If built, the AD plant may be amongst the most advanced in Europe and more akin to a food-processing facility than a traditional AD plant. Rather than conventional tanks and domes, known as a continuously stirred tank reactor (CSTR) system, the plant will use the Norwegian-developed Antec system.
The Antec system uses plug-flow AD reactors.
The Antec system uses plug-flow AD reactors, essentially large, sealed, rotating cylinders instead of conventional tanks. The cylinders are housed inside a building on the site.
John Jones, CEO of Utopia, which develops and operates integrated circular economy bioenergy parks and has partnered with Roadstone in Killough, said the Antec system is very different.
It significantly speeds up biogas production and will reduce conventional digestion times from around 50-60 days to nine days, on a much smaller footprint. The system operates at thermophilic temperatures of 55°C. The Killough plant will have 30 Antec reactors and will be the first of its kind in Ireland. Currently, there are eight plants of this kind operational in Norway. The Killough plant is based on the Vest Biogass plant in Norway.
Feedstock
The plant will be agri-based, requiring around 15,000t of chicken manure, 20,000t of cattle slurry, 60,000t of grass silage, 5,000t of maize silage and 5,000t of pot ale and spent grain annually as feedstock.
Climaticus director Maurice Deasy, who is assisting with communications and feedstock supply for the project, explained that feedstock terms, contracts and pricing arrangements have not yet been developed and will be co-developed with farmers. Feedstock would be sourced from farms within a 60km radius of the plant.
The plant will be agri-based.
The plant will pre-process its feedstock. An acoustic cavitation process will be used to break down the plant cell structure of the grass and silage, allowing it to be digested quickly. Jones estimates this system will increase grass yields by around 30%.
Ammonia will be stripped from the chicken manure, allowing higher throughput than unprocessed manure. The processed material will then mixed with slurry to create a homogeneous “bio-soup”, which will be heated to the required temperature before entering the reactors.
Output
Jones described it not as a biogas plant, but as a decarbonisation asset. The facility will convert feedstocks into five co-products: liquid biomethane, liquid CO2, electricity, organic fertilisers and water.
Biogas will be separated into methane and CO2, with total biomethane production estimated at approximately 8,880,000 m³. The biomethane will be purified to 99.99% and cooled to minus 160°C, producing around 6,000 tonnes of bio-LNG annually. This replaces earlier plans to compress and export gas off-site. As there is no nearby gas pipeline, gas will not be exported to the national grid. Some energy will be used on site, with the remainder exported.
Electricity and heat will be generated using a solid oxide fuel cell rather than a conventional combined heat and power (CHP) plant.
Feedstock terms, contracts and pricing arrangements have not yet been developed.
The CO2 will be cleaned and liquified, with options being explored to sell it in Ireland or generate new fuels. Digestate will be separated into solid and liquid fractions, with solids dried and pelletised and liquids treated to recover water for reuse within the AD process, or for fire and dust suppression. Jones pointed out that no water will be discharged.
Why AD
Pat Gibney, planning and property officer with Roadstone, explained that the AD plant would play a key role in decarbonising the company’s operations. Killough Quarry currently hosts an asphalt plant, a concrete plant, a limestone processing facility and ongoing quarrying operations. Roadstone’s total energy use in Ireland amounts to around 360 gigawatt-hours, while the proposed plant would produce 85 gigawatt-hours.
The intention, he said, is that the biomethane gas produced from the plant would be used to replace diesel and liquid natural gas currently used in these operations, with surplus gas exported to other end users. He said Killough was chosen because they own the site, it has an existing high energy demand and it is central.
However, he said they did not expect the level of community opposition to the plant. He said he thinks they have explained the project as best they can, but that there is misinformation out there about the proposal.
Lack of information
However, Alice Coleman, a member of the Killough Biogas Concern Group, believes that communication around the project has been poor. Speaking to the Irish Farmers Journal during the drop-in event, she said they felt the community was not given a lot of information about the project.
She said that she wants to see a community meeting-style event rather than a drop-in style event, so they can ask questions in front of an audience and have the answers on record for everyone to hear.
Biogas will be separated into methane and CO2, with total biomethane production estimated at approximately 12,170,000m³
Location
A key issue for her is the location of the plant. She said that she and her neighbours do not oppose AD technology, but feel the proposal is in the wrong location.
She said that she lives 500m away from the site and there are six to seven houses very close to the site. She said that planning guidelines are non-existent for these developments, with no legal minimum setback from houses.
When asked where they believed the right location was, she said that it should be located in Lisheen, Thurles, Tipperary, 20km north, where there are currently three plants in operation or in development, as it will not be close to houses.
Water
Another key concern of the group is the risk to drinking water, citing the proximity to an aquifer and the risk of the AD plant leaking. When this was put to him at the information event, Jones insisted that the entire site is sealed, double-bunded and can hold upwards of 150% of the total volume of the plant.
Therefore, if there were a catastrophic leak, it would be contained within the bund. Roadstone have said they will install four groundwater monitoring wells at the site to monitor groundwater quality.
Traffic
There is significant concern about the volume of traffic the plant would generate and the condition of local roads. Roadstone stated that the quarry and its ancillary activities are already permitted for up to 235 HGV movements per day and committed that the proposed AD facility would not increase this figure.
Other concerns
Coleman also highlighted concerns around explosion risk, LNG safety, quarry blasting adjacent to an operational AD plant, odour and the lack of clear community benefit from the project.
When asked how Roadstone could address these concerns, she said there was little they could do, adding that members of the group are prepared to “go all the way”, including a potential judicial review.
Site visit
Jones explained that there has been community engagement and that he has offered to bring locals to see an operational plant in Norway. He said that so far, they have brought 30 to 40 people over to Norway to see the plant.
Gibney said that a decision is due on 7 February and, depending on the outcome, the plant could be operational by 2029.
The author Stephen Robb is currently involved in a family/community proposal for an anaerobic digestion facility in Co Donegal.
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