The East Midlands Biogas Centre
The East Midlands Biogas Centre
On site we are utilising the heat generated by the CHP jacket water to maintain the right temperature for our large digesters, each holding 3,500 tonnes of food waste slurry. This creates the best environment for the friendly methane generating bacteria. Heat is also collected from the CHP exhaust flue to help run the pasteurisers, and by pasteurising before the material enters the AD process, this ensures the health of our system and protects against bacterial contamination.
Other exciting technology includes a mixing system with both, pumped jets of slurry and gas recirculation, for complete mixing and no in-tank components, meaning all maintenance is carried out seamlessly. Our H2s inhibitor detects when H2s is building up and pumps air into the digesters. This air feeds a bacterial culture on a net in the gas lid which eat the H2s. The results are dramatic and their biogas contains on average 30 parts per million (ppm), when up to 500 ppm is normal, this extends the life of the CHP and components. The biofilter ensures no odours escape into the local area and manages 3 air changes per hour of the Reception Hall.
A proportion of the renewable electricity generated is used to drive the electrical systems on site, such as the waste shredders, de-packaging machinery, material conveyors, control systems and of course the myriad pumps and valves that move the resulting food waste slurry through the AD process. In due course Bio Dynamic will install Solar PV on the roof of the waste reception building and it is calculated that the area of roof space available, being east/west orientation, will provide enough power to satisfy site demand during daylight hours.
Additional liquids, such as processed starch/sugar waters, beer waste, or food process liquids are brought to site and blended with the food waste to reduce the organic solids content to a manageable percentage. This means that the pumps and valve systems are operated at a much lower load factor than would otherwise be the case. The drive motors are run with variable speed drives thereby further reducing the energy required to be used on site. It also means that such liquid wastes are being utilised rather being discharged or treated unsustainably. In addition to these liquids, Bio Dynamic have installed a rainwater capture system that harvests the water runoff from the building and around the digesters. An historical borehole is also on site and is available to supplement the rain water harvesting, this water is heat treated using the renewable heat available and used for vehicle wash-down and machinery cleaning. This wash-down, which now contains some organic material is collected and recycled back into the front end process.
As the East Midlands Biogas Centre develops, the possibilities for becoming even more environmentally sustainable are very exciting. The plant is next to both the River Trent and a railway line offering the options of bringing waste to the plant by barge and/or train and taking the organic fertiliser away also by barge for example - possibly direct to farm land.
As Nottingham’s first and only food waste AD, Bio Dynamic is aiming to put the East Midlands firmly on the map. With ambitious expansion plans we hope to create more energy and more jobs for the local community now and for future generations. Watch this space!