Anaerobic digestion of verge cuttings for transport fuel Available to Purchase

Roadside verges need to be cut for both safety and ecological reasons. This requires energy, currently acquired from fossil fuels with associated release of carbon dioxide (CO₂). Leaving the cuttings in place has a detrimental effect on plant species richness; removal leads to increased biodiversity but produces green waste for disposal. This paper describes a model to determine the energy efficiency and surplus energy yield from the use of verge cuttings as a feedstock for anaerobic digestion. The model is scaleable and could be used by national and local authorities to find ways of reducing fossil fuel consumption. Although based on UK data, the same principles can be applied anywhere with roadside verges or similar sources of green cuttings. The model uses results from trials in Powys, Wales to determine the feasibility of collection and the potential methane yield of the cuttings. The results indicate that verge material can be collected in a manner that is both CO₂ neutral and produces more energy than that required for cutting, transporting and processing. The nature of the fuel produced means the process is self-sustaining—biogas can be used to fuel vehicles required for cutting and transport and to provide heat and electricity for the anaerobic digestion process.