Pyrolysis will convert poultry waste to biochar in major UK carbon removal project

Pyrolysis – heating in the absence of oxygen – produces biochar, a residue of nearly pure carbon, which can be infused into the soil, sequestering carbon indefinitely.

Onnu “will prevent phosphorous run-off and turn a problem into a revenue stream for farmers”

Aston University spin-off firm Onnu has announced plans to build what it says will be the first of 16 pyrolysis hubs in the Wye Valley. It will buy waste biomass from local poultry farmers and transform it into biochar.

Once all 16 hubs are completed, they will annually sequester over 500,000 tons of carbon – making this the UK’s biggest carbon removal initiative. Onnu says the multimillion-pound investment, spread over four years, will create more than 100 green tech jobs and will end the land-spreading that has caused well-documented damage to the River Wye and surrounding areas.

Disposal of poultry litter has become problematic and expensive due to the public outcry over the impact of phosphorous and other run-off on local eco-systems and stricter regulatory controls on land-spreading. “By using this waste biomass as a pyrolysis feedstock, we turn a problem into a revenue stream for local farmers,” said Giles Welch, CEO of Onnu. “The resulting biochar will be used as a safe and transportable organic fertiliser forming part of a circular economy in UK agriculture. This is the only genuinely sustainable solution to the problems facing the Wye Valley.”

Onnu will open an office in the Herefordshire area later this year with six staff, including two land acquisitions experts. The company says it has identified four potential locations for its first site which is planned to start operating in April, 2024. “These hubs will be no larger than a typical barn and are completely self-contained, self-sustaining units with underground storage,” explained Welch. “They will create no discernible noise or odours so their operation will have no impact on the surrounding areas.”

Onnu plans to build these 16 hubs across Herefordshire, Shropshire and Powys by 2027. They will each be strategically located a few minutes’ drive from several dozen local poultry farmers to minimise traffic to and from the site. Each hub, consisting of two pyrolysis machines, can process 10,000 tonnes of waste biomass each year: once all 16 hubs are built, 1.6 million tonnes of waste biomass would be processed annually, sufficient to account for all the poultry litter produced in the Wye Valley catchment.

Onnu is registered with the Puro.Earth carbon registry and biochar from the Wye Valley hubs will qualify for CO2 Removal Certificates (CORCs). Once each site is operational for 10 years, the project is expected to have generated 350,000 tons of biochar and 580,000 CORCs. The proceeds from the sale of these will ensure that the hubs are cash-generative and will also be shared with the farmers through the purchase of their waste biomass.