Recycling revolution begins in blood and guts

The Sunday Times
May 24, 2009

A power station that can run on rotting food? Danny Fortson discovers it’s an idea not to be sniffed at

Darren Renshall can’t help himself. As he approaches a spigot amid the din coming from a maze of pipes, he smiles, pulls the lever and out slops a pile of foul-smelling black sludge.
The odour is revolting. But the engineer doesn’t seem to care. He is clearly excited about the muck, which is piling up like a mound of mashed potato on the floor. It is what makes this power station, in Widnes on the Mersey, like no other. Instead of using coal or gas to generate electricity, this plant runs, quite literally, on blood and guts, a cocktail of the food industry’s leftovers. The “fuel” contains slaughterhouse bone and meat, mouldy bread, rotten fruit, old ready meals and fish entrails that “look like thousand island dressing”, said Renshall, who runs the plant.
Each day about 30 lorries bring all types of unwanted food and animal remains here, where it is mulched together in giant tanks to form a homogenous purée. It is then injected into boilers where it is incinerated at 1,000C. From that point, the plant works like any other power station, creating steam to power a turbine to generate electricity.
If you think it sounds disgusting, you’re right. But PDM, the company that owns the plant, has seen a surge in interest from supermarkets and slaughterhouses in its method of dealing with waste. Britain produces more than 12m tonnes of food waste a year and a government directive means that landfilling is quickly becoming too expensive. It is also bad for the environment because, as it breaks down, organic waste releases methane, which, as a greenhouse gas, is 22 times more damaging than carbon dioxide.
Companies are well aware of both problems and that has led to a surge of interest in PDM, especially from retailers that are conscious of their “green image”.
By July, J Sainsbury has pledged to cut to zero the 70,000 tonnes of food waste — about the weight of the Titanic — that it once sent to landfill each year.
Much of what once would have been buried is now fed into the furnaces at Widnes. Tesco, Wm Morrison, Asda, the Environment Agency and the drugs giant Novartis (which sends the residue of eggs it uses to grow flu vaccines) are also clients. “Whatever they bring, we’ll burn it,” said Renshall proudly.
The Widnes site is one of 23 operated by PDM, a family firm that traces its roots to the 1920s when Prosper De Mulder, a Belgian refugee, opened a cheese and bacon stall near Crewe. Over the decades it branched out into the rendering of livestock and poultry waste. Today the Doncaster firm is the country’s largest food recycler, processing more than 1m tonnes a year.
The De Mulder family ranks 406th on the Sunday Times Rich List with a fortune of £130m. Prosper F De Mulder, 93, son of the founder, is still chairman. His son Anthony, 65, is managing director.
Most of PDM’s sites process food waste to make products for candles, pet food or bricks. Widnes is the only power plant but that is about to change as PDM hopes to cash in on what Philip Simpson, commercial services director, said is a “fundamental change in the way the food industry handles waste”.
PDM has signed a joint venture with one of the largest food recyclers in the world, Germany’s Saria BioIndustries, to build a network of food-collection centres and anaerobic digestors to process food that would otherwise be buried. “Before, the supermarkets only ever thought about doing it because it was green but now they are looking at it because of costs as well,” said Simpson.
Anaerobic digestors are steel tanks that act like stomachs by using enzymes in an oxygen-starved environment to break organic waste into methane gas, which can be burned to create electricity, and solid digestate that can be spread on land as fertiliser. The process is less energy intensive than incineration and qualifies for the government’s renewable obligation subsidy scheme, which makes it attractive financially.
However, anaerobic digestors are limited in what they can process, so PDM plans to build more so-called “wet-burn” facilities like the one at Widnes, which came about after the mad-cow disease epidemic of the late 1990s. That was when the government passed a law requiring the destruction of all cows over 30 months old and prohibited the use of animal proteins in livestock feed.
This fired PDM’s work on wet-burn technology, which uses a mix of organic matter that is about 60% moisture. Much of the process comes down to mixing whatever may come in the front end — bones, blood, milk, eggs — to create a homogenous purée to fuel a constant and predictable chemical process. Simpson said: “If it’s too wet, it will put out the fire. If it’s too dry, the combustion will be unstable.”
PDM later developed a facility to feed in other waste, such as ready meals and bread. Lorryloads are fed into a machine that separates out the packaging and grinds the food into a porridge-like mixture that is then fed into the rest of the system. The packaging, reduced to shreds of plastic, is sent to landfill but little else is wasted.
After more than 80 years of handling dead animals, PDM is adept at finding value where others prefer to look away. Holding up a jar of tallow and another of finely ground bone, Simpson made the point. “That and that plus water was a cow,” he said. “It has two-thirds the value in terms of energy. The potential is huge.”