With at least 18 large-scale anaerobic digestion (AD) plants currently at various stages of the planning process, the Irish biomethane industry is poised to rapidly take off.

These plants are at different stages of planning, with some having secured planning permission, others in the midst of planning, an appeal or judicial review, while others are just about to start the process.

As clear Government direction and support policies are lacking, developers are exploring alternative ways to make these AD projects viable by identifying markets that currently require renewable biomethane gas.

One such market is the heavy goods vehicle (HGV) sector.

Diesel-powered HGVs produce up to 20% of our road transport emissions but only account for 3% of vehicles on our roads, making the target to decarbonise the sector by 50% by 2030 a challenge.

Ninety-nine per cent of Ireland’s some 40,000-strong HGV fleet are currently diesel-powered.

One such way to reduce emissions in the HGV sector is to switch from using diesel as a fuel to compressed natural gas (CNG).

CNG can reduce CO2 emissions by up to 23% and nitrous oxide emissions by up to 50% compared to diesel.

While conversions from diesel to CNG are possible, in most cases, this involves changing the lorry altogether.

However, to significantly decarbonise the sector, the HGV would have to be fuelled with compressed biomethane (bioCNG).

BioCNG is now available in limited quantities at a number of service stations around Ireland and can reduce transport emissions by over 90%.

Biomethane

By 2030, the Government aims to have 5.7TWh of biomethane produced and used annually, which would require the development around 200 large-scale AD plants.

Many of these plants will be connected and inject the renewable gas directly to the gas grid. Farmer involvement will be critical, as most of them will be agriculture-based, fed with grass silage and slurry. Although a significant portion of this biomethane is intended for heat decarbonisation, buyers and companies that use high volumes of fuel for heat have been slow to commit to purchasing biomethane. However, one market that is already here and is poised to grow significantly is bioCNG.

CNG HGVs currently have a low market share in Ireland but continue to grow in popularity.

The current number of CNG-capable HGVs on Irish roads is low. In 2023 so far, just eight new CNG HGVs were registered compared to 1,193 diesel HGVs.

However, under the Government’s Road Haulage Strategy, this number could increase to 3,500 by 2030.

Refuelling stations

Central to achieving this target is the rollout of CNG refuelling stations. There are currently seven CNG stations operational in Ireland, with 10 more private and public stations in the pipeline.

Gas Networks Ireland (GNI) and Circle K launched Ireland’s first public, fast-fill CNG refueling station at Circle K’s Dublin Port premises in December 2018, which could fill up to 70 HGVs a day.

A second public CNG station opened in July 2020 at Circle K’s Cashel premises on the M8 motorway, providing fleet operators with a fast-fill CNG location along the Cork to Dublin motorway.

In 2021, two additional public CNG stations opened at Ballysimon Road, Co Limerick, and Clonshaugh, Co Dublin. Many of these were developed through the EU-funded Causeway programme. There are also several active private stations in use today.

BioCNG

While CNG has been available for a while, bioCNG has only been offered at the four public refuelling stations for the last six months. GNI recently released emissions reduction statistics from using bioCNG in these stations.

According to GNI, in the six months that bioCNG has been available at the four Circle K outlets, almost 1,900 tonnes of carbon emissions have been saved, equating to over 1.9m carbon neutral kilometres. These carbon emissions reductions are attributed to the transport sector.

The biomethane used in the stations was made and injected into the grid by an AD plant in Kildare. The biomethane is certified by the International Sustainability and Carbon Certification and qualifies as a renewable fuel under the Irish Biofuel Obligation Scheme, allowing suppliers to meet their renewable obligations.

GNI’s Renewable Gas Registry tracks the allocation of the biomethane from the point of injection into the grid to the point of withdrawal at the Circle K refuelling stations.

The author Stephen Robb is currently involved in a family/community proposal for an anaerobic digestion facility in Co Donegal.