Speaking at the AD In the City event held in the UK by BiogenGreenfinch in April 2009, senior consultant, Dr Adrian Gibbs, said that using AD to process food waste collected separately could work out cheaper than processing commingled food and green waste together in an in vessel composting plant.
explained that a report by Eunomia
had found that sending food waste to AD and green waste to windrow composting cost UK councils £9.50 in gate fees per household per year, whereas sending commingled green and food waste to IVC cost £10.80 per household.
also said that just collecting food waste alone and sending it to AD cost £5.50 per household over the same period.
admitted that average gate fees for AD facilities - around £55 per tonne - were higher than IVC - which, he
quoted as £45 per tonne, but said that "overall AD is cheaper".
also claimed that separate food waste collections also worked out cheaper than mixed collections and said that the number of local authorities which were implementing separate collections had risen from 11 in 2007 to 54 in 2008.
told the London borough council officers who attended the event, which was set up to explore ways to introduce more AD capacity in London, that - "AD is better than IVC, it's the way to go and it is the one I would watch.
However, Dr Gibbs
explained that the seasons significantly affected what was collected, with garden waste levels dropping significantly in the winter, meaning that feedstock was inconsistent.
also said that the waste had to be processed in an enclosed environment due to Animal By-Product Regulations and this ups the cost of green waste.
also pointed out that green waste and food wastes required different collection frequencies.
In addition, not all homes have gardens and collecting green and food waste together prevented councils charging for green waste collection.
claimed that separate Anerobic Digestion waste collection reduced net costs for councils and allowed local authorities to charge for garden waste.
added that there is a large quantity of food waste which could potentially be picked up.
said AD had a number of strengths, including -