Onnu, in partnership with ReGenEarth, is pioneering a fully circular integrated anaerobic digestion (AD) and pyrolysis project.

Located at ReGenEarth’s Sedgefield site, Hope Farm, an operational dairy farm supplying Arla, the development sees the expansion of the existing AD facility into a multi-purpose hub for renewable energy generation, carbon removal, and circular farm-based sustainability.

Already powered by cattle waste, the site will now incorporate self-sustaining biochar production through Onnu’s CarboFlow pyrolysis technology.

In the fully circular process, agricultural residue is fed into an anaerobic digester, with the digestate byproduct dried using green energy from the pyrolysis process. This is then pyrolysed itself to create a soil amendment in the form of biochar, sequestering carbon. Residue from harvesting the crops is then used to fuel further anaerobic digestion, thereby starting the process again.

The partnership follows the first commercial deployment of CarboFlow last month in Southeast Asia, where the system will process large volumes of tropical agricultural residues and enable high-integrity carbon removal operations.

The project forms part of ReGenEarth’s £100m green bond programme with RER Capital, with a view to a nationwide rollout of integrated AD–pyrolysis sites supported by enhanced feedstock provenance tracking and high-integrity carbon credit pathways.

Once operational on the 3,500-acre farm, the system is designed to deliver 2,266 tonnes of biochar annually, 2.8 MW of recoverable thermal energy and 4,300 tonnes of carbon removal, eligible for carbon credits under the Puro Earth framework

---