Recycling food waste through anaerobic digestion - not just energy and fertiliser

When we talk about the benefits of recycling food waste through anaerobic digestion, we often talk about the energy we can produce and the fertiliser. But here I outline not only those benefits but a significant number of other benefits that need to be added to the list.

The UK produces over 10 million tonnes of food waste each year, or 13 million tonnes when food residues from factories are included. With avoidance measures, such as redistributing surplus food to the hungry, the UK should be aiming to reduce this to 8 million tonnes in the next 15 years.

What should we do with this remaining waste?

We could put it out in black bin bags for collection with all of our other leftover waste. Far better for everyone though, would be to send it to anaerobic digestion (AD) plants. These plants use micro-organisms to break down the food waste into energy used in our homes and fertiliser used to grow more food.

Sending it to AD would provide the UK with:

  • 9 terawatt hours of energy, enough to heat 740,000 homes each year and reduce our dependence for gas on unstable regions of the world such as the Middle East and North Africa
  • Reduced carbon dioxide emissions of 1.9 million tonnes per year, equivalent to removing 700,000 cars from the road
  • 80,000 tonnes of natural fertiliser – this helps replace factory-produced fertiliser, the production of which is responsible for 400,000 tonnes of carbon dioxide emissions in the UK per year
  • Avoided methane emissions from landfill – although landfill caps now prevent most of the methane from food waste leaking into the air, about 25% of methane produced by landfills is still emitted to the atmosphere

Sending food waste to AD requires separating the food waste at the household and business level from the other waste and recycling. This requires an initial investment to get up and running, estimated at £55m for households in England, or 0.007% of UK government spending.

Also required would be for the emitters of greenhouse gases to pay for the damage those emissions cause. With world business leaders and others now identifying the damaging impacts of climate change, whether extreme weather events or large-scale migration, as one of the most serious risks the world faces, there must be a price on carbon, or equivalent support for renewables such as AD.

Other benefits

But as well as energy security and greenhouse gas benefits, separating food waste for collection delivers other benefits, including: reducing food waste as people become more aware of the food and money they are wasting; reducing the contamination of recycling collection (again, with better understanding of waste); and saving councils money as our standard black bags become less smelly and don’t need to be collected so frequently.

If it’s so great – why isn’t it already happening?

It is! Scotland, Northern Ireland and Wales have already mandated separate food waste collections. England has just been slow.

We now need central government to support local authorities that want to do the right thing, and put the legislation in place to make this UK-wide. Having consistency across the UK would also help all of us know which waste we put in which bin!

So we'll continue to lobby DEFRA to support the roll-out of separate food waste collections across England.

Posted in: Policy updates

Tags: anaerobic digestion, food waste, Ollie More