The BBIA and associated member companies have commissioned Sancroft International to undertake a detailed cost analysis of the implications of different food waste caddy liners – including PE bags, compostable plastic bags, paper bags and no bags.

This is in view of the mandate for all councils to offer separate domestic and business food waste collections in England post 2023 and is written with the intention of helping policy makers at a national and local level, to understand which system is the most environmentally and economically beneficial for the nation.

Whilst the research was funded by those parties, the results and conclusions belong to Sancroft. Sancroft undertook a range of interviews both with operators and stakeholders across the UK over the summer of 2020. It used the results of the data collected to build a model which is to be found in Annex 1.

It looked at

  1. The comparison in costs between using PE bags, composable plastic bags, paper bags or no bags at all
  2. The existing cost of extraction and disposal of non-compostable contamination from food waste treatment prior to digestion or composting
  3. Potential cost savings through sending separated bags and food waste to compost rather than burning separated plastic
  4. Benefits in terms of soil quality and contamination of food systems
  5. Benefits in yields and resource efficiency through encouraging households to segregate waste and reducing contaminated waste streams

Sancroft modelled the systems in a graphic which shows existing and future collections indicating how resources would flow differently in the two scenarios. The graphics are contained in Annex 2. The model Sancroft have produced has looked at what could vary within the policy preferred AD stream – assuming that the food waste sent to IVC with compostable bags already will continue to do so, this is not of concern in the study.

The principle concern is whether AD plants will face higher costs from moving away from plastics in food waste collections to compostables and Novamont, Sphere Group, Compostable Bag Company, Cromwell Polymers, Biome Biotechnologies. whether those costs are justifiable in a resource efficient future.

The detailed analysis of the study is in Annex 3. The conclusions are clear: “The evidence shows that the most cost-effective option that delivers the biggest benefits for the nation is the use of compostable bags as a liner, as the most effective balance of reasonable costs, minimisation of plastic contaminants in the biodegradable waste stream and maximisation of total food waste collected and processed. Based on that logic, the priority is first compostable bags, then paper bags, then lastly no bags and PE bags, since both have significant downsides whether in plastics contamination or poor yields and high GHG emissions.”

The report will be presented and discussed by its authors on 25 January 2021 at 2pm (UK time) in a webinar.