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Energy from food waste – Rockfire Capital looks at the figures

food waste and anaerobic digestion

As the Notting Hill Carnival prepares to generate enough waste to fill 25 double decker buses, the team at Rockfire has decided, in the wake of its article on anaerobic digestion, which cited the 200 million tonnes of waste produced in Britain each year [1], to ask how much of this waste is from food.

The answer is 7.5% of the total: 15 million tonnes [2].  Around half of this food – 7 megatonnes – is wasted at home and half of that – 4.2 mt – is classified as avoidable. WRAP, the charity that researches and compiles these figures, provides a topical image to help with visualising that amount of food: 4.2 million tonnes is enough to fill 8,400 Olympic swimming pools.

In a country where over a million people were fed from food banks last year, the social discomfort arising from these figures is evident. Less obvious, perhaps, is the cost to the economy (£12bn) and to the environment (an estimated 17mt of carbon dioxide emissions from production, transit and storage, a figure that puts household food waste on a par with a quarter of private car journeys in the UK).

Food wastage is also quite high in the hospitality sector at almost a million tonnes. This equates to one in six of the eight billion meals served each year, and the corresponding costs are £2.5bn and 3.6mt of CO2 equivalent.

Where does all this waste go?

At least 40% goes to landfill, a destination that is widely regarded as undesirable since it releases methane, a greenhouse gas that makes carbon dioxide look like a babe in arms in terms of potency (although it does dissipate in the atmosphere more quickly than CO2 and can be captured and processed for electricity production).

Of the remaining 60%, 22% is treated as sewage, 15% is incinerated or used in landspreading to produce energy, and a further 15% is composted or placed in anaerobic digesters.

Landfill is not only undesirable, it has also become extremely expensive since the introduction of the Landfill Tax in 1996. Most waste operators such as SITA, Biffa and Veolia are closing landfill sites and turning their attention to extracting gas from existing subterranean refuse.

So policy and society have driven the economics and opened the market to alternative technologies. In-vessel composting (IVC) is one of these, and companies such as Earthworm in Northamptonshire seek to take advantage of the post-landfill landscape.

However, it looks as though anaerobic digestion (AD) could well be the winner, as DEFRA is on record as envisaging a fivefold increase in the UK capacity for AD treatment of food waste by 2020 –  to 5mt.

[1] Environmental Services Association from Eurostat
[2] Waste and Resources Action Programme
[3] DEFRA: Government Review of Waste Policy in England, Anaerobic Digestion Strategy Plan