It’s the third and final day of the International BiocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More Initiative’s fantastic study tour of Wales, and we’re jumping across the border to just outside Cheltenham. The stop took a look at the newly constructed ‘missing link’ for the A417, being constructed by Kier in collaboration with TerrAffix. The project is building a nature bridge over the highway, utilising biochar in the soil to improve growing conditions for vegetation that would be vulnerable to heat stress and drought.

The new £460 million A417 Missing Link Scheme in Gloucestershire will connect Gloucester and Cirencester with a new three-mile dual carriageway. As part of this project, a 197ft long and 121ft wide bridge is being built to create a crossing for walkers, cyclists, horse riders, and wildlife. The planning development has been so well received, that Kier (the construction company in charge) have received no objections, which is rare for such a large infrastructure project. The bridge itself, connecting habitats on either side and allowing for species migration, is a fraction of the project cost and represents industry best practice. They noted that the project has spent £8 million on archaeological works, recovering some 10,000 artifacts of varying reverence. In addition, £5 million has been spent on ecological assessments and relocations, which have reached similarly impressive numbers with bats, lizards, snakes and more being relocated.

The project has deployed a number of environmental improvements to mitigate their impact. They have been using Soil Science’s ‘Sureground’ chemical on soils to harden them for haul roads, which mitigates the need for sub base imports that would raise emissions. Zero material is going off site. They estimate an emissions reduction of 39%, which exceeds the targets set by the National Highways. Nevertheless, the key focal point for the tour was on the biochar component. This was replacing an artificial gel that is usually integrated under the soil on the concrete to retain moisture. As the bridge is still being built, the total biochar application by weight is not defined; the application rate, however, is set at 5% to soil weight. It is expected that the char will be used for tree planting, establishing a resillient buffer zone for the bridge. Unfortunately, because a lot of the components for the project are precast, there is minimal scope to experiment with char-infused concrete.

To produce the biochar for the project, TerrAffix deployed their newly developed (1st of its kind) relocatable pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More unit. The site space they took was only 0.3 acres, showing their system will seamlessly integrate into site and because it needs no plug ins, the system space can be reclaimed once needed. They also noted that the entire unit could be setup in a week and dismantled in just under a week. They processed 217 tonnes of wet material, but one of the significant challenges they have faced is feedstockFeedstock refers to the raw organic material used to produce biochar. This can include a wide range of materials, such as wood chips, agricultural residues, and animal manure. More contamination – likely due to cement and metal from multiple points of contact handling. A big struggle, as a result, was a yield conversion of 13-14% by weight, but I was told that this was an outlier because they had achieved 24-25% at another project. This was achieved, despite using G50 chip – larger than the typical G30 – so a yield so close to the 27% sweet spot is very impressive.