Ten years back only a handful of anaerobic digesters dotted the English countryside. Now the number has skyrocketed, with 730,000 kilowatts pumped into the National Grid by 558 AD plants in only the first three months of 2017, according to the Anaerobic Digestion & Bioresources Association (ABDA).
And though 292 of these still controversially feed off purpose-grown crops, a growing number are relying on the millions of tonnes of surplus food increasingly supplied by local councils, restaurants, major supermarkets and manufacturers. Only this month ReFood opened its brand new Dagenham plant, capable of processing 160,000 tonnes of food waste each year and generating enough power to keep the lights on in more than 12,000 homes.
“I’d love to say the growth has been about people’s awareness of food waste,” says Bio Collectors MD and founder Paul Killoughery. But the drivers behind the explosion in AD are in reality more economic and political than ethical. “The main driver is really that it’s now competitive in comparison to landfill and incineration in cost,” he says. That’s partly thanks to the introduction of a hefty tax slapping £86 per tonne on the gate fee for landfill, and partly to a cash injection into AD from a government increasingly eager to be seen as green.
Nearly 300 of the UK’s 558 anaerobic digestion plants are fed in part on crops grown on arable land, some for the express purpose of being churned into green gas. In fact, 2.2 million tonnes per year of maize, beet and cereals are turned into feedstock for fuel.
“A third of maize grown in the UK is going into AD,” believes Philip Simpson at ReFood. “I think that’s ridiculous when food waste could be used.”
But, says industry body ABDA, this has to be looked at in context.
“Growing crops for AD in the very highest scenarios would still only use under 1% of the UK’s agricultural land,” says chief executive Charlotte Morton.
What’s more, “the growing of crops as part of an agricultural rotation is a proven farming method, used to improve soil quality and food production yields and to reduce pesticides and herbicides.
From 2010 Feed In Tariffs have been made available to AD plants, guaranteeing a price for the electricity they produce. “Investors want a long-term return and if you have a market living from year to year then investors don’t want in. That’s what happened before subsidies came in,” says Killoughery.
This new certainty has encouraged new investment and new plants, while enabling AD operators to charge only £20 per tonne on average to customers, says ABDA. “Without subsidies it would be similar if not higher than landfill,” admits Killoughery.
So, what’s the problem? On the face of it, nothing at all. As Philip Simpson, commercial director at ReFood, explains, AD acts as a “cow’s stomach on an industrial scale” blending and homogenising huge volumes of food that would otherwise have ended up in a hole in the ground, with even its liquid waste byproduct used as a fertiliser, “closing the loop all the way back to the farm”.
FareShare’s director of food Mark Varney readily accepts “anaerobic digestion is a fantastic technology”. However, all too often it isn’t only inedible food that ends up making its way to an AD plant. Of course, “once food is out of the food chain and turns up at an AD site all of the organic matter will be inedible” he says.
Crops for AD
Nearly 300 of the UK’s 558 anaerobic digestion plants are fed in part on crops grown on arable land, some for the express purpose of being churned into green gas.
In fact, 2.2 million tonnes per year of maize, beet and cereals are turned into feedstock for fuel.
“A third of maize grown in the UK is going into AD,” believes Philip Simpson at ReFood. “I think that’s ridiculous when food waste could be used.”
But, says industry body ABDA, this has to be looked at in context. “Growing crops for AD in the very highest scenarios would still only use under 1% of the UK’s agricultural land,” says chief executive Charlotte Morton.
What’s more, “the growing of crops as part of an agricultural rotation is a proven farming method, used to improve soil quality and food production yields and to reduce pesticides and herbicides.
Farming needs to consider how to grow crops in a way that benefits the environment, and feedstocks for AD are no exception”
But before that, “most food manufacturers are understandably focused on trying to ensure all their stock is sold for the intended purpose. If, for whatever reason, this doesn’t happen, it can often quickly become waste. And stock that has ‘no or limited commercial value’ gets disposed of with the other inedible stock.”
It’s a situation that FareShare says is only exacerbated by the gap in costs between AD and charitable redistribution, with the latter up to five times the price per tonne when sorting and transport are taken into account.
The result is little economic impetus to separate the perfectly good food that might have been left over or mislabelled from the true waste material.
“Edible food is not something we knowingly target,” insists Simpson. Not least as there isn’t anywhere near enough capacity in the AD market for all the inedible surplus out there, and won’t be any time soon.
After the government kicked off a gradual removal of subsidies in 2015, the growth rate of new plants has dropped from a 25% increase year on year in 2014/15 to only 1% in the last 12 months.
On top of that “we always stress the food waste hierarchy with all our customers” he says. “Unavoidable food waste should go to the charity sector first or sold at a discounted rate, and if it can’t be used as human food it goes to animal feed, then AD and composting. Above all else, never landfill.”
But both Killoughery and Simpson admit that AD operators can’t be at their clients’ factory or store dictating what goes into the wastebin and what gets sent for redistribution, if any.
And though Killoughery rightly says supermarkets and other businesses have “taken huge strides in making sure more goes to FareShare”, no AD operator “can control” what each business sends where. “The trouble with the legislation is - it’s their choice,” he says. “Even if it’s perfect. Even if it’s a gold bar we couldn’t take it out and sell it. That’s the legislation. It’s still classified as waste.”
And even food waste frontrunner Tesco admits still depositing a few metaphorical gold bars in its AD collection bin. Despite a 148% increase in edible food sent to charity in 2016, some of the 38,653 tonnes it shipped off to AD in 2016 was “safe for consumption”, though it plans to stop this by the end of this year.
“Stock that has ‘no or limited commercial value’ gets disposed of with the other inedible stock”
One half of the solution is companies adopting a waste management plan, says FareShare. “That means they identify where and when surpluses have occurred in the past, with an action plan agreed across the business to ensure food that cannot be sold is provided to a redistribution charity, and only if not edible is it then sent for animal feed, anaerobic digestion or composting,” says Varney.
But the charity has also called repeatedly - as has our own Waste Not Want Not campaign - for government cash to help level the playing field. At five times the price of AD, the moral high ground simply isn’t enough impetus for all companies to commit to separating out and redistributing their edible food. At current rates of redistribution it would cost the government less than £5m per year (with subsidies at £100 per tonne) to cover the cost of shipping perfectly good food to charities instead, with millions of tonnes of surplus still left to fuel anaerobic digesters.
The growth of anaerobic digesters across the UK churning rubbish into renewable energy might be a magical thing. But it should reserve its magic for the waste, and leave the food for empty stomachs.
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