Client: SGN
Date: September 2025
Project Team: Lorenza Carta, Consultant, Sophie Mason, Senior Consultant & Lucy Hopwood, Director and Principal Consultant
Project External Link: Biomethane Islands | FEN Innovation Portal
Background: To meet its Net Zero targets of 2050 for the UK and 2045 for Scotland, the gas system has to transition away from fossil fuels towards low carbon alternatives. Biomethane offers a proven and scalable solution, but its wider deployment within the gas network remains constrained by technical, regulatory and commercial challenges. In response, Scotland Gas Networks (SGN) is exploring the concept of Biomethane Islands, defined as self-sufficient sections of the gas network supplied entirely by locally produced biomethane, as a pathway to accelerate decarbonisation while supporting circular economy outcomes.
Objective: SGN commissioned a consortium of specialist advisors to assess the feasibility of developing Biomethane Islands in three Scottish locations: Inverness, Drakemyre and Edinburgh. The objective was to evaluate whether these towns or cities could be fully supplied by biomethane produced via anaerobic digestion (AD) and to assess the regulatory, technical, environmental, social and commercial viability of the concept. The study aimed to inform investment and policy decisions and to establish a framework that could be replicated across Great Britain.
Our Approach: Working as part of a multidisciplinary consortium, Alder led the assessment of feedstock availability and digestate management options. Using Alder’s internal feedstock database and public datasets, the team evaluated the availability, seasonality, composition, competing demand and pricing of agricultural and organic waste feedstocks within a 50-mile radius of each candidate location.
In parallel, Alder assessed digestate management options by reviewing local land availability, existing agricultural practices and interactions with other AD facilities, as well as alternative treatment and market options, as appropriate. This ensured that the type, volume and composition of digestate generated could be managed sustainably within each proposed Biomethane Island. These findings were integrated with wider technical, network, regulatory and financial analysis undertaken by project partners to deliver a comprehensive feasibility assessment and business case.
Outcomes and benefits: The study provided SGN with a robust, evidence-based assessment of the feasibility of Biomethane Islands in Scotland, highlighting the conditions under which self-sufficient, biomethane powered gas networks could be delivered. The findings demonstrate how locally sourced feedstocks and circular AD systems could decarbonise gas supply, improve waste management outcomes and support rural and regional economies. The work will be used by SGN and other networks to consider more novel approaches to gas production, distribution and use in the future.