Case Story United Kingdom

Towards carbon neutrality in on-farm biomethane production from break crops

December 2025

Summary

Apsley Farms, operated by Yelspa Ltd, is a pioneering enterprise located in Hampshire UK which combines traditional practices with innovative technologies to optimise bioenergy production, reduce carbon emissions and enhance sustainability. It is the UK’s third-largest biomethane plant, and has been supplying renewable natural gas to the UK gas grid since 2014. It operates one of the world’s largest crop-based digesters which, at 89 m long and 9 m deep, holds 18,000 m³ of digestate in an innovative lagoon design.

The size and location of the plant have allowed key decisions to be made on its mode of operation with the goal of moving towards carbon neutral on-farm biomethane production. Through innovation around crop ensilement, pre-hydrolysis, long retention, low downtime and operational resilience, the plant has achieved 385 Nm3 CH4 per tonne of organic solids, making it one of the most efficient farm-based biomethane and CO2 facilities in Europe.

Low carbon farming techniques tailored to biogas production

Feedstock is around 90,000 tonnes per year of Maize, Rye, Barley, Oats or Grass grown in rotation on the 465-hectare estate or at local farms. Apsley Farms uses a range of techniques to improve agricultural sustainability, including:

• Minimum tillage and use of cover crops to reduce soil disturbance and carbon emissions
• Effective digestate utilisation to maintain soil health and reduce synthetic fertiliser needs
• Precision farming with real-time control of nutrient addition and monitoring of crop growth through to harvest
• On-field storage and ensiling using the AgBagTM system to reduce crop losses, minimise the size of silage clamps and decrease vehicle movements for transport