Mayo County Council has granted planning permission, subject to conditions, for an anaerobic digestion (AD) plant near Ballinrobe.

The planning application was submitted by local pig farmer John Sheridan and Nephin Renewable Gas – Ballinrobe Limited in July 2024.

The proposed AD plant on a site of approximately 4.4ha will take in 90,000 tonnes of locally sourced manure/slurry, whole crop silage and other organic material to produce biomethane.

The application states that 71 local farmers are willing to supply feedstock to the proposed plant.

The development would involve the construction of three digesters which would be around 16m in height, two digestate storage structures, two pump houses and two liquid feed tanks.

The plans also include pasteurisation tanks, solid digestate storage and a nutrient recovery building, odour abatement plant, an ESB substation and a two-storey office and administration building.

The proposed development at a site within the townlands of Levally, Cappacurry, and Knocknadrimna will, according to the application, create employment opportunities in the locality with approximately 75 full-time positions.

Anaerobic digestion is the process by which micro-organisms break down organic matter in an oxygen free environment to produce biogas that comprises mainly methane as well as carbon dioxide (CO₂).

The methane will then be separated and separated to produce biomethane, which will be injected into the gas grid via a pipeline that will be constructed between the site and the existing distribution gas pipeline.

A by-product of the process is a digestate or bio-fertiliser that will be used to re-fertilise the land from which the crops/fuel is sourced.

As well as planning permission, an industrial emissions license is required by the Environmental Protection Agency (EPA) as well as approval to operate from the Department of Agriculture, Food and the Marine (DAFM).

It is proposed that the facility will be fully constructed and operational by 2026, and will run on a 24/7 basis.

Two third-party submissions were made to Mayo County Council objecting to the proposed development.

The concerns raised include the nutrient profile of the lands from which crops will be obtained to serve the development, the loss of biodiversity in the wider area, and a lack of public consultation with the local community.

In its submission, An Taisce said that supplying biogas to local off-grid industrial users would be a preferable alternative to the proposal as it stands, provided it is used for electricity generation and is not mixed with fossil gas.

The National Trust for Ireland added that it must be determined that proposed feedstocks are sustainable and that their production "will not exacerbate ongoing issues" with greenhouse gas emissions and water quality deterioration.

Mayo County Council granted planning for the development, subject to 28 conditions.

"Having regard to the policies and objectives of the Mayo County Development Plan 2022-2028, it is considered that the proposed development would be in accordance with the proper planning and sustainable development of the area," the local authority said.

The local authority said that it is satisfied that the proposed development individually, or in combination with other plans or projects would not adversely affect the integrity of European sites, provided that the mitigation measures contained in the Natura Impact Statement (NIS) are implemented.