The second public consultation on Roadstone’s proposed anaerobic digestion (AD) plant at Killough quarry in Co Tipperary took place this week, with the company responding to questions and listening to concerns from residents.

The proposed AD plant would be located within the Killough quarry and would operate as a significant agriculture-based liquid biomethane, CO2 and organic fertiliser facility.

First submitted for planning permission to Tipperary County Council in January 2025, the project has drawn significant opposition from local residents.

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Key concerns raised include traffic volumes, odour, potential explosion risk, potential water contamination and the impact on property values.

The consultation took the form of a drop-in event, hosted by Roadstone along with its project partners Utopia, which is co-developing the facility. Climaticus, which is assisting with communications for the project, was also in attendance.

Project details

Planning and property officer with Roadstone Pat Gibney 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.

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. This plant would be the first in a series of similar facilities planned by Roadstone.

Feedstock

The AD plant would require approximately 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 Deasey explained that feedstock terms, contracts and pricing arrangements have not yet been developed and will instead be co-developed with farmers. Feedstock would be sourced from farms within a 60km radius of the plant.

He added that, as part of the company’s engagement process, Climaticus has contacted all 160 third-party objectors to the planning application, as well as those who have submitted observations, with varying levels of engagement to date.

High-tech facility

Utopia CEO John Jones, which develops and operates integrated circular economy bioenergy parks, outlined the technical specifications of the proposed plant.

The facility is set to be among the most advanced in Europe and would not rely on conventional continuously stirred tank reactor (CSTR) technology, which is the case for all other plants in development.

Instead, it would use the Norwegian Antec system, a newer AD technology that allows material to break down more quickly and effectively than traditional systems, producing higher biomethane yields from the same feedstock.

The plant would incorporate advanced technologies for ammonia stripping, feedstock pre-processing, digestate treatment, water recycling, CO2 and biomethane liquefaction, as well as full heat recovery integrated into the operation.

‘Wrong location’

At the time of visiting the consultation, approximately 40 people had attended so far, including members of the local Killough Biogas Concern Group.

Speaking to the Irish Farmers Journal, local resident Alice Coleman said the group is not opposed to AD plants, but believes the plant is being developed in the wrong location. She explained that her home is located within 500m of the site.

She also expressed serious concerns about locating the plant on a porous limestone quarry location, as well as the increased road traffic the plant would generate.

Coleman said many locals feel they have not been adequately informed about the project and called on Roadstone to hold a formal public information meeting rather than a drop-in style consultation.

A full report on the project and the consultation event will appear in next week’s Irish Farmers Journal.