Estimates of waste produced by food manufacturers and processors vary widely. The government’s new waste strategy says the sector produces 7.2 million tonnes per year, of which 4.1 million tonnes is food waste (see pp 34-38 ). About 1.9 million tonnes of the sector’s waste is landfilled.
But these figures are derived from a 2002/03 Environment Agency survey of just 579 of the sector’s 8,000 manufacturers. In its recent final report,1 the Food Industry Sustainability Strategy’s waste group recommends using returns under the integrated pollution prevention and control regime to establish a baseline, but recognises this would only include about 340 of the largest sites.
However, a 180,000-tonne capacity pyrolysis facility proposed by waste technology company Inetec could cut the amount of waste the sector sends to landfill significantly, regardless of total arisings. North East Lincolnshire Council granted planning permission for the £69 million plant at Immingham in May
The plant will be built and run by Inetec subsidiary EnCycle and is due on stream by the middle of next year. It will be capable of processing mixed food and packaging waste, which will come from Northern Foods, Greencore - one of the UK’s largest manufacturers of convenience foods - and bakery business Greggs.
In addition to process waste, the waste will include returned goods. These are sent straight to landfill by food companies because it is costly to separate packaging from its contents. Greencore will send sauces in glass jars to the plant because the cost of emptying the jars and separating the food, glass, metal and paper is too high, even with income from recyclate.
The pyrolysis process has three stages. The waste is first shredded and dried, leaving a "powder with small shards of packaging", according to Ed Mant, Inetec’s spokesman. This is fed into the pyrolysis unit, which heats the waste to 800°C in the absence of air and produces syngas for burning in conventional gas engines.
The plant will produce about 66MW of heat and 24MW electricity, which will be fed into the grid. The biomass fraction of the waste will be eligible for Renewables Obligation certificates. The ash residue, equivalent to 2% of feedstock, will be landfilled.
The plant has several advantages over technologies like anaerobic digestion, according to Mr Mant. "No other technology can take packaging as well as food waste," he said. "To go to anaerobic digestion the food would have to be segregated and that just adds to costs." Anaerobic digestion also requires a constant stream of food waste to work efficiently, he said, and cannot cope with variable arisings resulting from just-in-time production methods.
Inetec hopes to build ten plants over the next five years to process 1.5 million tonnes of waste. The plants would be located close to other clusters of food processors in areas such as the Midlands and the south-west.
The company says it has already signed contracts to take waste equivalent to half the capacity of a second plant, but Mr Mant would not say with whom, where the plant might be located or when a planning application will be submitted. Inetec will conduct an initial public offering on the London Stock Exchange in July to raise £28 million to fund it.
Both Greencore and Northern Foods were keen to stress that the plant would not replace efforts to minimise and recycle waste. "For us it’s a last resort - one above landfill," said James Cherry, environment manager at Greencore, "but after strong recycling programmes we’ve ended up with contaminated packaging we can’t recycle and food waste we can’t use for animal feed."
Greencore has signed a three-year contract for waste from all 16 of its sites, mostly in Yorkshire and the East Midlands, as well as Humberside. The company is hoping later plants will reduce the distance waste has to travel.
Several other food manufacturers are investigating the technology. Paul Walsh, Cadbury Schweppes environment manager, said discussions with Inetec were under way. "While on-site treatment may not be economically viable due to the low volumes of waste generated by our factories, a collaborative venture… close to one of our sites at Bournville or Keynsham is of interest." Other firms seem less interested. Steve Bradley of Associated British Foods said it was "doing good sound management but not using new technologies." He would not comment on the Inetec process.
Pyrolysis’s environmental benefits have also been questioned by environmental groups. "We are still promoting anaerobic digestion as the best process for food waste," said Michael Warhurst, senior waste campaigner at Friends of the Earth. "We’re sceptical about pyrolysis - and gasification - in terms of their carbon efficiency as you’re basically burning mixed waste when it should be segregated."
He added that any company that used a plant on-site was probably not doing enough to minimise waste and was "effectively generating enough waste to power a small incinerator".
The government’s Waste and Resources Action Programme (WRAP) has begun trials of kerbside food waste collections with 17 local authorities. The trials, which will run until March, will look at how collections work in different areas as well as how to treat the material.
It has also published the final version of a study by consultancy Eunomia looking at the options for managing food and garden waste, including a cost-benefit analysis.2, 3