Earlier this year launching The Scottish Government’s Zero Waste Plan, Environment Secretary Richard Lochhead said: “Scottish households produce over half a million tonnes of food waste each year at an average cost of £430 per household.

Staggeringly, this equates to a third of the average ‘black bag’ rubbish sent to landfill, where it breaks down to produce methane – a greenhouse gas 21 times more damaging to the environment than carbon dioxide.”

This is National Zero Waste Week. To celebrate we publish this from the ENDS Report on food waste and the positive potential for a better system:

The UK aims to avoid sending household food waste to landfill by recycling it into fertiliser and biogas. Philip Lightowlers and Nicholas Schoon examine whether council’s food waste collections and anaerobic digestion plants can fulfill their potential

A council truck disposes of food waste collected from households in Lynmouth, Devon (photo: Mark Boulton/Alamy)The UK throws away 16 million tonnes of food every year, according to an estimate by the Waste & Resources Action Programme (WRAP). Getting this waste out of landfill sites should be a high government priority for cutting greenhouse gas emissions.

About half of this waste emerges from households, rather than companies making or selling food, and most still ends up in landfill sites where it rots to produce methane – a far more potent greenhouse gas than carbon dioxide. Some of the remainder is incinerated, but only a small fraction is recycled.

WRAP estimates that 5.2 million tonnes per year of this waste is avoidable, meaning that it could have been consumed (vegetable peelings and used coffee grounds are examples of unavoidable waste). UK households spend £12bn a year buying this food and then getting rid of it – an average of £480 per family. But there is far more at stake than money.

The 5.2Mt represents huge quantities of water and fertiliser wasted in growing the food. It is also estimated to lead to the equivalent of 20Mt of annual CO2 emissions – 3.5% of the UK total – much of it in the form of methane from landfill.

For several years WRAP has tried to raise household awareness of food waste with its Love Food Hate Waste campaign, which educates people in portion control, better storage methods and how to save and use leftovers. But although cutting household food waste at source is a worthwhile aim, large quantities are bound to keep coming out of our kitchens.

There is a broadly agreed goal to collect more of what remains separately, rather than mixed up with other household waste, to keep it out of landfill. Instead, the food can be sent to an anaerobic digestion (AD) plant, which turns it into methane biogas and a digestate that can be used as fertiliser.

The biogas is a renewable resource which can substitute for finite natural gas in generating heat and power (ENDS Report 404, pp 30-33). And if the digestate is substituted for carbon-intensive, non-renewable synthetic fertilisers, further greenhouse gas savings will be made.

AD is generally considered a better environmental and economic option for recycling food waste than its main rival, in-vessel composting, which does not produce any useful gas.

Patchy distribution

What Britain needs is a smooth and rapid increase in the provision of food waste collections by councils, matched by more AD plants being built by the private sector, with both collections and plants spread evenly across the UK.

If this were to happen, the problem would be cracked in a decade or so; all food waste would be turned into useful biogas and digestate, and none would go to landfill.