Converting food waste into green energy, two new combined heat and power generation plants have been developed, but only received planning permission because operator Agrivert and sara LBS guaranteed that neither plant would emit unpleasant odours. Agrivert provides sustainable and cost effective organic waste management solutions across the UK, including anaerobic digestion, in-vessel composting, green waste composting, and the treatment and recycling of bio-solids for the water sector.
The UK produces over eight million tonnes of food waste every year, most of which ends up in landfill, where it emits the greenhouse gas methane. Agrivert’ offers an alternative solution in which food waste goes through anaerobic digestion to produce biogas for powering engines which drive generators, which are typically on-site. Further, the solid by-product is a valuable and effective fertiliser.
At Stormy Down and Colney Heath Agrivert is running food waste fuelled electricity generating plants, each of 3MW capacity and able to power about 6,000 homes. As relatively large capacity sites, they require an almost constant flow of vehicles delivering food waste for use as feedstock, which has the potential to create enough malodorous emissions to cause concern for neighbours.
To overcome this, each site has a large food waste reception building into which the collection vehicles drive before discharging their load. For efficiency, there are two sets of doors at both ends of the building, all supplied by sara LBS. The trucks come in at one end and exit at the other so that arriving and departing vehicles do not impede one another.
As part comprehensive package of odour mitigation measures Sara doors were selected because of their swift opening and closing times and a high proven degree of reliability. Working together, Agrivert and sara LBS developed a concept whereby the doors would all be interlocked so that only one could be open at any time, preventing ‘through draughts’ that could release odours to the local environment.
The interlocking arrangement also ensures that the doors shut again promptly, thus minimising the time for potential emissions escape. A mechanical ventilation system that keeps the building under slight negative pressure was designed for each building. The ventilation systems discharge to atmosphere through odour abatement equipment.
Stormy Down is in fact a decommissioned RAF base and now is home to an expanding array of environmentally-friendly facilities including a wind turbine, a field of solar panels, an eco-house and a plant that converts industrial waste into low-carbon cement. There are plans to add a second wind turbine, a pioneering 10MW battery storage project and a hydrogen refuelling station.
The Colney Heath plant has been built at Coursers Farm, near Willows Farm Village – a local recreational and educational farm attraction. Much of its feedstock will come from the nearby South Mimms motorway service station, where Agrivert operates an in-vessel composting facility.
Both sites produce enough fertiliser to improve over 3,000 acres of local arable land, allowing farmers to reduce their use of hydrocarbon derived products.
Brian Hunt of Agrivert said these projects are the fourth and fifth to use sara Sprint doors: “The projects have all been either three or four door configurations and are to a height of 5m, allowing access by the specialist food waste collection vehicles, although the width has varied from project to project.”
sara LBS’s range of fast action, Sprint doors offer the fastest operating speeds of any roller shutter door. The Sprint high speed security door is based on an extruded aluminium curtain combining security, speed and an ability to cope with high usage. Low maintenance is a key benefit due to its reliable performance, even after long-term high intensity use.
The Sprint’s speed of operation makes it ideally suited for applications where added security and/or biosecurity are required. The opening speed can be as high as 2.5m/s, allowing a fast response in situations such as the unexpected arrival of a delivery vehicle. Closing speed is more sedate, up to a maximum of 0.7m/s to ensure safety of personnel. The fast operation can also significantly reduce the time the door is open, thus allowing the building to retain heat (or in food production and similar applications, cooled) air and thus reducing energy loss.
sara LBS’s Alan Ryder commented: “The Sprint range of roller shutter doors can be made in a range of sizes and including a number of different options. As a result a custom door that suits each application’s special requirements can be produced promptly and cost effectively.”