Mayo has a long and complex history with gas infrastructure. The development of the Corrib Gas Field in the early 2000s marked a significant milestone, but it was the onshore pipeline that became the source of much debate and controversy. Despite this, the county’s only remaining domestic gas resource continues to be a significant contributor to Ireland’s national energy supply, meeting around 20% of the country’s annual natural gas demand.

However, Mayo’s gas industry is evolving and the county has become the leader in green gas development. There are currently two biomethane projects and three hydrogen projects under development in the county, a combined total greater than any other county in Ireland.

Why Mayo

But why Mayo? The legacy of the Corrib Gas Field has left the county with a modern, high-quality gas network. It’s reasonably well-served by electricity infrastructure. Supply chains, trade expertise and services developed in the region around the Bellanaboy Bridge Gas Terminal, which brings gas from Corrib and feeds it into the national gas pipeline, also makes the county attractive.

Mayo also has excellent wind resources, making onshore wind production particularly viable in the region, which is essential for renewable electricity generation needed for hydrogen production.

While the suitability of anaerobic digestion (AD) at scale may not be as favourable in Mayo compared to other parts of the country, there is still an ample supply of slurry, silage and farmers to supply feedstock to the plants, as well as some waste sources. Moreover, Mayo’s relatively low population density is helpful for reducing planning objections and providing space for large-scale infrastructure projects.

These attributes help explain why Mayo is seeing so much development in the renewable gas sector. This article explores some of the key renewable gas projects currently underway in Mayo.

Hydrogen

Mayo leads the country in the number of hydrogen projects currently in development. Green hydrogen gas is produced through a process known as electrolysis, where renewable electricity is used to split water into hydrogen and oxygen.

While large-scale hydrogen production is still in its early stages due to cost and infrastructure challenges, the Government has set a target of developing 2GW of hydrogen by 2030. Gas Networks Ireland has demonstrated that blending up to 20% hydrogen into the national gas grid is technically feasible. Below are the main plants currently in development.

  • Killala: One of the latest projects to receive the green light in Mayo is the Killala Hydrogen Plant and Energy Centre, located on the site of the former Asahi synthetic-fibre plant at Killala Business Park. The development is led by Limerick-based Constant Energy Ltd.

    • The Hydrogen Plant will include a two-storey electrolyser unit, coolers, hydrogen storage, a tube-filling station and a gas injection compound. The adjacent Energy Centre will house nine gas engines capable of generating up to 106MW of power, all located within a dedicated engine building.

    The hydrogen will be produced on-site via electrolysis, using borehole to source the water. The hydrogen gas will be temporarily stored and transported off-site by tube trailer trucks.

    The hydrogen will then be blended with natural gas and injected into the national transmission network or used to fuel the Energy Centre’s nine gas engines for flexible power generation.

  • Bellacorrick: The Bellacorrick project, located at Croaghaun West and Srahnakilly near Bellacorrick village in north Mayo, is a 114MW gas-fired peaking plant approved in January 2024 and led by Constant Energy Ltd. The development includes two open-cycle gas turbines capable of operating on a blend of natural gas and hydrogen, with a new 110 kV substation on a 4.35ha site. It is designed to provide flexible backup power during periods of low renewable generation.

    • Adjacent to the peaking plant, the company has also secured permission to build a hydrogen production facility. This plant will supply some of the fuel required by the turbines or allow hydrogen to be injected into the gas network.

  • Firlough: This projects straddles between Mayo and Sligo. The Firlough project, led by Mayo-based Mercury Renewables, received planning permission in November 2024 from An Bord Pleanála. It comprises a 78MW onshore wind farm with 13 turbines at Bonniconlon, Mayo. Co-located in Curraun, Castleconnor (Sligo), is an 80 MW green hydrogen electrolyser capable of producing around 4.5 million kg of green hydrogen annually from the wind farm’s electricity. The hydrogen plant is designed to produce approximately 4.5 million kg of green hydrogen annually, enough fuel for nearly 17,000 cars, 125 trains or 1,400 buses.

    • Biomethane

    Mayo was an early mover in biomethane development, with projects underway well before the publication of the National Biomethane Strategy. The county is set to host one of the first modern agri- and waste-based plants in the country, located in Ballinrobe.

    This plant could become a key reference point for farmers and communities, offering a place to visit and learn from. Two plants are currently in development, with more in the pipeline.

  • Ballinrobe: As previously reported in the Irish Farmers Journal, Nephin Renewable Gas’s first plant is located near Ballinrobe and is being developed, in partnership with local pig farmer John Sheridan. Approved in April 2025, the facility will process up to 90,000t of organic material annually, including cattle, pig, and poultry slurry, silage, and food processing residues sourced from over 70 local farms. The site will produce grid-quality biomethane for injection, along with liquid CO2 and digestate to be returned to farms. The plant has faced little to no opposition.
  • Lisgennon: The second project is in North Mayo near Killala and was approved following an appeal to An Bord Pleanála in early 2024. The plant, being developed by local dairy farmer John Gilvarry, will process up to 60,500t/year, made up of grass silage and slurry. Biogas produced on-site will be exported to the national gas grid via an 8.6km underground pipeline.
  • Swinford: The proposed biomethane plant near Swinford, by Moy Valley Biogas Ltd, faced two planning refusals after significant opposition. Designed to handle approximately 48,000t/year of slurry and silage feedstock, following the appeal decision, no judicial review was lodged, leaving the refusals final. The Irish company behind the plant remains active with other projects in development.

    • Corrib repurposing

    In August 2022, joint owners of the Corrib Gas Field, Vermilion Exploration and Production Ireland and Nephin Energy, launched the Atlantic Energy @ Corrib. The initiative aimed to assess the potential for repurposing the Corrib Gas Field facility in Bellanaboy into a renewable energy hub. The Corrib field is expected to run out early in the next decade.

    Since the launch, technical and economic screenings have been carried out to evaluate renewable energy options, including wind energy and hydrogen production. The project is now in a detailed feasibility phase, focusing on the commercial and technical viability of the proposed developments. The site’s existing infrastructure and grid connection are among the factors being considered in planning its future use.