Background
Ireland generates around 750,000 tonnes of food waste every year, with households, food manufacturing, and hospitality as the largest contributors. This poses both an environmental challenge and an untapped opportunity. At the same time, Ireland’s National Biomethane Strategy aims to scale biomethane production from 0.075 TWh today to 5.7 TWh by 2030, in line with Europe’s REPowerEU plan.
Anaerobic digestion (AD) offers a dual benefit: managing organic waste while producing biomethane that can substitute fossil gas, and a nutrient-rich digestate that can replace mineral fertilisers. But with market volatility and inflationary pressures, how feasible is food-waste-to-biomethane today?
Insights from our study
Our recent publication in Sustainable Energy Technologies and Assessments by Martinez-Arce A and Kargupta W et al., 2025 explores this question by simulating a biomethane plant processing 50,000 tonnes of food waste annually. Using SuperPro Designer modelling, we carried out a combined techno-economic assessment (TEA) and life cycle assessment (LCA).
Key findings include:
- A plant of this scale can produce ~26 GWh of biomethane per year, equivalent to 2.78 million Nm³ for grid injection.
- The levelised cost of biomethane (LCBM) is 249 €/MWh, nearly 3× higher than 2019 levels due to inflation and rising utility costs.
- Breakeven requires gate fees >69 €/tonne or policy supports such as carbon credits or Renewable Heat Incentives (RHI of 0.1 €/kWh).
- From an environmental perspective, food-waste-to-biomethane delivers up to 222 kg CO₂eq savings per tonne of food waste, but uncontrolled methane leaks can cancel out these benefits and cause €120k–215k annual revenue losses.
- Digestate management aligned with the Nitrates Directive can boost climate benefits, but trade-offs in nutrient emissions (eutrophication, acidification) need careful management.
The sensitivity analysis highlights the significant impact of market variables and policy instruments on the financial viability of biomethane projects in Ireland. Fig a below illustrates the variation in net present value (NPV) with changes in biomethane selling price across different gate fee
levels. Without gate fees, the breakeven price aligns with the levelized cost of energy (249 Euro/MWh), whereas gate fees above 69 Euro/tonne
are required for breakeven with a biomethane selling price of 111.7 Euro/MWh (household gas price), emphasizing the strong influence of gate fees on financial profitability.
Fig b below shows how ±25 % changes in CAPEX and OPEX-particularly equipment and utility costs-substantially affect production costs. This reflects the capital-intensive nature of anaerobic digestion in Ireland and signifies the importance of cost control and targeted support measures such as Renewable Heat Incentive (RHI), carbon- credits, or capital grants.
Future opportunities
Ireland’s National Biomethane Strategy (2024) has set a clear ambition: to increase production from just 0.075 TWh today to 5.7 TWh by 2030, delivered through around 200 new AD plants. While the Strategy highlights cattle slurry and grass silage as core feedstocks, it also recognises the important role of industrial organic wastes, including food waste, which could contribute up to 0.5 TWh annually.
Our study shows that a single plant treating 50,000 tonnes of food waste per year can deliver ~26 GWh of biomethane, while also generating nutrient-rich digestate. Replicated at scale, 20 such facilities could help deliver the industrial waste fraction of Ireland’s biomethane target.
Beyond volume, our research offers insights that can shape the way Ireland builds this new sector:
- Sustainability frameworks: The Strategy proposes a new Biomethane Sustainability Charter. Our findings on methane leakage and digestate management provide evidence to ensure climate and nutrient circularity are measured and achieved.
- Policy support: Achieving cost parity (currently 249 €/MWh vs. fossil gas ~112 €/MWh) will require the kinds of supports outlined in the Strategy-such as Renewable Heat Obligation (RHO) and capital grants. Our economic modelling shows exactly how these can bridge the gap.
- Deployment pathways: With the Strategy calling for a mix of large grid-connected and smaller regional plants, our model of a mid-sized food waste facility is directly relevant to the “smaller plant” category, offering a replicable blueprint.
- Community engagement: The Strategy emphasises building public confidence. Our research can be shared in digestible infographics and case studies to help communities understand the environmental benefits-and risks if emissions are not controlled.
By combining policy ambition with robust scientific evidence, Ireland can build a biomethane sector that is not only scalable, but also circular, sustainable, and trusted by the public. Food-waste-to-biomethane may not deliver most of the supply, but it is a strategic contributor that aligns perfectly with national climate and circular economy goals.