Anaerobic Digestion and Food Waste Recycling: Opportunities for an alternative, sustainable method of waste disposal and energy generation

Jonathan Croley is a Partner in the Energy & Resource Management team at Ashfords LLP (Credit: Ashfords LLP)

In this thought piece, Jonathan Croley and Benjamin Thomson from Ashfords LLP tell ICON readers about the opportunities Anaerobic Digestion offers as local authorities must comply with the requirements of the Environment Act 2021.


The changes to waste collection law introduced by the Environment Act 2021 (EA2021) will significantly impact how waste collection authorities collect and dispose of waste. At the same time local authorities are under budgetary pressure to balance the books, as well as political pressure to achieve Net Zero by 2050.

This article will detail the challenge local authorities face in light of the new duties imposed by the EA2021, and how one solution exists that will help local authorities discharge those new duties in a way that creates an asset from liability and contributes towards achieving Net Zero.

Changes to waste collection and recycling

EA2021 will legally require waste collection authorities to:

  • collect “recyclable household waste” (which includes food waste) separately from other household waste;
  • collect food waste at least once a week; and
  • recycle all of the waste which cannot be redistributed.

There is currently no fixed timescale for the new legal duties to come into force, but it is expected that most local authorities will have until 2024/25 to implement separate food waste collection.

The separate collection of food waste will be a logistical and budgetary challenge for the many local authorities that do not currently separately collect food waste, especially for those authorities that have already contractually committed to the disposal of co-mingled waste to waste processors on extended contracts.

Some local authorities may need to completely rethink the collection of recyclable household waste in order to arrive at an efficient, economic and effective collection solution that complies with the new legal duties imposed by the EA2021.

Net Zero

The UK is committed to achieving Net Zero by 2050.

“Net Zero” refers to the balance between the amount of greenhouse gas (GHG) released and removed from the atmosphere.

Not all GHGs have the same warming effect on our atmosphere, and so Net Zero is measured in terms of the equivalent warming effect of carbon in the atmosphere.

The continued use of fossil fuels moves the UK away from achieving Net Zero, and so a key part of achieving Net Zero relates to displacing demand for fossil fuels or products created using fossil fuels.

With carbon capture technology still in its infancy (and coming with a significant energy cost), the near-term strides on achieving Net Zero will be achieved by reducing GHG emissions, which means reducing usage of fossil fuels and reducing demand for products and services that are dependent on fossil fuels.

Anaerobic Digestion (AD)

AD is the process by which organic matter (including food waste) is broken down by micro-organisms, releasing a methane-rich gas that can be used to generate renewable heat and power: powering industry, heating homes and fuelling vehicles, all whilst displacing demand for fossil fuels.

AD also produces nutrient-rich digestate that can be used as an alternative to conventional fertilisers derived from fossil fuels, and closes the nutrient loop.

Even the CO2 created in the AD process can be captured and refined to be used in industry (displacing the demand for fossil-fuel CO2) or put into long-term storage.

A key feature of AD is that it captures the methane which would otherwise be released into the atmosphere if the material were composted or sent to landfill. As methane is a powerful GHG, burning the methane to produce heat and power contributes more positively towards achieving Net Zero than simply allowing the methane into the atmosphere.

Conclusion: putting it together

The separately-collected food waste will need to be treated, and local authorities should focus on treatment solutions that contribute most towards achieving Net Zero.

AD can be used to treat the separately-collected food waste and contribute towards Net Zero in one step, by treating the material in a way that minimises GHG emissions and creating products that displace demand for fossil-fuel derived (and contra-Net Zero) products, such as fuel and fertiliser.

As AD realises the inherent value of organic wastes, local authorities’ separately-collected food waste is transformed into a resource. As a resource, local authorities will hold an asset rather than a liability mitigating the budgetary impacts associated with complying with the new duties imposed on them by the EA2021.

Benjamin Thomson is an Associate in the Energy & Resource Management team at Ashfords LLP (Credit: Ashfords LLP)