28/07/2022
In 2021, the UK Government made separate food waste collection mandatory for households in England by 2023. This legislation, imposed as part of the Environment Act 2021, is designed to accelerate the transition to a circular economy and tackle significant challenges of waste generation.
In England, 50% of local councils are currently collecting food waste separately or as part of their green waste collection. However, some 6.6 million tonnes of household-produced food waste is either disposed of in landfill or incinerated, where it emits carbon dioxide and methane gas as it breaks down. These gases are released uncaptured into the atmosphere, resulting in net carbon release.
According to Kerry Mashford OBE, Energy Strategy Lead for Worcestershire Local Enterprise:
“Waste collection and disposal authorities will need to work fast to devise local solutions across the almost 50% of Local Authorities that do not currently provide separate food waste collection, and potentially modify the rest to comply – all for implementation during 2023/24.”
Anaerobic digestion (AD) technology is now increasingly employed across the UK to generate useful products from waste, particularly food waste. In 2021, industrial capacity for food waste recycling using AD was 3.2 million tonnes of input. With the introduction of mandatory separate food waste collections, millions of tonnes of additional food waste will become available for processing. This naturally shines the spotlight on capacity, and whether the country has a sufficiently sized infrastructure to deal with the new model. Until the industry expands and develops to catch up with supply of refuse, excess waste will have to travel greater distances to sites which might have spare processing resource. This may bring unwelcome offsetting of CO2 emissions and transport costs, meaning that the country could be creating more carbon emissions by transporting waste than it is capturing carbon by processing it.
As Kerry Mashford comments:
“We need to consider how food waste collection will fit in the wider energy system, using this opportunity to advance the energy system transition to a net zero future, by carefully considering the size, distribution and siting of AD plants, including potentially closer coupling of these to local uses of biogas such as in heat networks or commercial vehicles.”
All of this highlights the need for innovative means and measures to process food waste effectively.
Biogas
Food waste is a fruitful source of green gas, with much greater methane production potential as other starting materials for AD. As energy prices soar and the world looks towards renewable energy generation and energy independence, capturing the energy from food waste has gained large-scale governmental and industrial attention.
AD is a series of processes in which microorganisms break down organic matter in the absence of oxygen to produce biogas and digestate. Biogas is a mixture of gases, primarily carbon dioxide and methane. The mixture can be used directly to power houses and factories, or fuel vehicles and enter the National Grid if upgraded to biomethane (pure methane produced from biogas). The relative quantities of each gas produced varies depending on the biological agents involved in the reaction and the reaction conditions. Biomethane is the most useful component of biogas, and so efforts are being made to tilt the balance towards production of methane and away from CO2.
Patent databases indicate that the control and measurement of reaction parameters is the subject of earlier research in the field, whereas more recent advances relate to optimising biogas output through developing novel bioactive compositions. For example, European patent no. 3808850 B1 provides biological cocktails of a consortium of bacteria and enzymes, with an optional host of biostimulants, which enhance methane production. Further innovation in the field focuses on the pre-treatment of food waste before it is processed. Chinese patent application no. 106698879 discloses hydrothermal hydrolysis pre-treatment of food waste to improve AD efficiency and methane production.
Digestate
Another huge focus of food waste recycling is on the production of biofertilisers, such as digestate. Digestate is the material remaining after the digestion process, and contains all of the recycled nutrients that were present in the original organic material but in a form more readily available for plants to absorb. Biofertilisers restore the fertility of the soil after crop production, and enhance water-holding capacity of the soil, which are gradually lost with prolonged use of chemical fertilisers. Again, a lot of innovation is in directing the digestion process towards producing valuable digestate, including enzyme and bacteria additives and reaction parameters.
Challenges facing the food waste collection scheme
The UK government is currently offering £295m of funding to go towards the collection of food waste (e.g. procuring new vehicles). However, the costs of processing, disposal and building new treatment facilities will need to come from local authorities. Lack of governmental funding is limiting critical developments in infrastructure required to process additional residential food waste.
One potential solution to this financial problem has been developed by Ørsted. Ørsted has created a first-of-a-kind technology called Renescience that is able to greatly increase recycling rates from unsorted refuse, negating the need for refuse sorting. The technology mixes water and enzymes with municipal waste, breaking down all organic material, such as food waste, labels and food that adheres to packaging and cans. The resulting bioliquid is drained and can be sent to an anaerobic digestor to produce biogas and digestate. The technology also simultaneously sorts the remaining refuse according to material composition, such as metal and plastic, for further recycling.
Ørsted’s bioenergy facility in Northwich, Cheshire, treats approximately 80,000 tonnes of waste per year, equivalent to waste from around 70,000 homes. Technology like Renescience may lessen the pressure on funding for separate collection of food waste, which can be directed towards further innovation in this area instead. However, unless more funding is provided to the AD sector, incapacity to process an increased supply of food waste will have knock-on effects for the government’s 2050 net zero target.
This article is for general information only. Its content is not a statement of the law on any subject and does not constitute advice. Please contact Reddie & Grose LLP for advice before taking any action in reliance on it.
