16 July 2017
If you’ve ever eaten at the National Exhibition Centre (NEC) in Birmingham there’s every chance your leftovers, potato peelings and more, could be powering Severn Trent’s sewage treatment works at Coleshill. The NEC has become one of the first local businesses to send its food waste to Severn Trent Green Power’s £13 million East Birmingham anaerobic digestion (AD) plant.
Chris Jellett, Severn Trent Green Power’s food waste anaerobic digestion expert, explains:
Whether it’s a sandwich shop or a fast food outlet – the leftovers, known as ‘food waste’, from the NEC site, which includes both the NEC venue and Genting Arena, will be powering sewage treatment at Coleshill.
We started constructing the plant within Coleshill sewage treatment works last year and it’s now taking in food waste from local businesses to power the site. Rather than food waste going to landfill, which is costing businesses more and more, we’ll be stopping around 8,000 tonnes of CO₂ from being released into the local environment – that’s equivalent to taking 3,300 cars off UK roads. To add to that, every year we expect to generate around 17,000 Megawatt Hours of electricity from the food waste AD plant, which is enough to power around 4,000 homes or the whole of Coleshill sewage treatment works and more. This means that the site will be totally self-sufficient for its electricity needs.
Brian Pell, the NEC’s director of operations, said:
Sustainability is at the heart of everything we do and we are continually looking for new ways to make our venue more environmentally friendly. Thanks to our on-site Waste Pre-Treatment Centre, we send zero waste to landfill and are committed to ensuring that any waste that travels off site for further processing never travels more than 30 miles – this helps to save CO₂ emission during travel and keeps our costs down too.
Severn Trent’s site is right on our doorstep, less than four miles away, so it provides us with the perfect location to send our food waste. This year, we expect to send around 120 tonnes of food waste to Coleshill to help generate a huge amount of power for the site.
The plant works just like a human, eating a sweet
Severn Trent’s Chris continues:
Food waste is packed with energy, which – with a bit of ingenuity – can be unlocked and turned into power. The process works in a similar way to us eating food. Trucks full of food waste are the ‘hands’, delivering food into the ‘mouth’ of the plant which is contained in a sealed building – acting like ‘lips’. Within the mouth, food is unwrapped by a machine, which removes the plastic that goes for recycling. The waste food is then ‘chewed up’ by another machine and sent straight into the anaerobic digestion tanks, the ‘tummies’, for digestion.
The anaerobic digestion ‘tummies’ process different types of food waste. As that happens, methane gas – similar to a ‘trump’ – is produced and collected on the top of the tank, without being released into the air. It’s then sent over to a machine, like the ‘heart of the plant,’ called a combined heat and power unit (CHP), which turns it into green energy to power the works. There’s then leftover material which is pasteurised so it is totally clean, meaning it can be used as fertiliser on local fields. The whole digestion process takes around 90 days from the plant mouth to field. And, the best thing is that this carries on 24/7, 365 days a year.