STANDFIRST: Ever wondered what happened to the leftover food you through away? Oxford Mail reporter Michael Race takes a look behind the scenes at how the waste is recycled to produce enough energy to power thousands of homes.
THE leftovers get scraped off plates into the food waste bin and to most members of the public will never be of use again.
But unbeknown to them, much of the leftover grub from Oxfordshire's households is taken to a 'digestion' facility where it is transformed into fuel for electricity and nutritious fertilisers.
Foods ranging from potatoes to pineapples are ground up, stored in 'human stomach-type digesters' where they produce bio-gasses, predominately methane, which are converted and used to power the plant itself as well as about 4,200 homes.
As one member of staff at the Anaerobic Digestion Plant in Cassington put it to a group taking in the facility's strong surrounding smells - they encourage methane to be produced, unlike others who may discourage it
The three-acre plant off the A40 processes 50,000 tonnes of food waste - 35,000 solid and about 15,000 of liquid - every year.
Private company Agrivert run the plant 365 days with just three members of staff.
It was first commissioned in September 2010 following its 8-month construction costing £9m.
All recycled food from homes in Oxford, Vale of the White Horse, West Oxfordshire and South Oxfordshire comes here.
Agrivert commercial manager Pamela Lloyd and contract manager Debra Barnacle give a public tour of the site as part of an Oxford City Council project to encourage more residents to recycle food waste.
The pair explained the process of how waste is transformed into electricity - with the leftovers used as fertiliser.
Council waste trucks are weighed before and after they dump the waste, which is then ground up in a 'bunker' before to create an 'organic soup'.
The black gunk is then pasteurised at 70 degrees to kill off bacteria and potential diseases, before it is pumped into five digester tanks, which are 4,500 cubic metres big.
Having being stored at body temperature and mixed all together, the methane gas then is harvested and converted into electricity.
Silage is sometimes added and the digester's can get 'sick' if they don't agree with what is being fed to them - just like humans.
After about 80 or 90 days, the left over 'soup' in the digesters is sold to farmers as fertiliser.
Ms Barnacle said to the group: "The more gas we get the better is is for the site. We may discourage it at home but we encourage it here."
Mrs Lloyd added the plant produced 2.1mega watts every day which is enough to run about 4,500 homes all day, every day.
She said the 'net effect' of recycling the food, rather than it going to landfill 'was the equivalent of taking 71,000 cars off the road every year'.
Ms Barnacle said Oxfordshire was one of the first areas to take up food recycle on a big scale and added it was 'very forward thinking'.
The city council say more than 20 per cent of the county’s food waste gets binned and hope to reduce that figure.
Councillor John Tanner, board member for a clean and green Oxford, said: "I want to send a big thank you to all those who already recycle their food waste - more and more of you are putting it into the green caddy for weekly collection.
"But still too much of this valuable resource is being chucked in the green rubbish bin and then incinerated. If it’s food it belongs in the caddy, not the green bin.
"Food waste is too valuable to waste. No amount is too small."