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Case study – SOURCE by LEAP: turning food waste into bioenergy and urban food production opportunities

Approximately 64% (931,000 tonnes) of total food loss and waste generated in London[1] comes from households. Much of this food waste can be avoided, for example through lifestyle changes, but some of it cannot. Where food waste is unavoidable, there is an opportunity for it to be recovered as a bioresource that can be used as an organic fertiliser or biofuel.

When not collected separately from ordinary waste and recycling, food waste is sent to landfill where it emits powerful greenhouse gases or to incineration, where it comprises the efficiency of the process and results in polluting emissions. In both cases, valuable nutrients, fibre, bioenergy, and water are lost.

Through capturing the value in unavoidable food waste and using the by-products to grow food for local communities, SOURCE is pioneering new urban circular systems. Decentralising and downsizing typically highly intensive processes like anaerobic digestion is challenging but it has the potential to reduce food and waste miles, while generating clean energy and supporting green training and employment opportunities. However, achieving this in cities, where the concentration of food waste and demand for food is highest, presents various logistical, spatial, and technical issues.

What was the response?

LEAP’s SOURCE project is significantly increasing the processing capacity of an existing biodigestion system from 15kg to 150kg of food waste a day from social housing residents. Alongside addressing the technical challenges of local food waste recycling, LEAP, with project partner public works, are undertaking ongoing community engagement exercises to help shift behaviour towards increased recycling and better separation of food waste. To ensure consistency and alignment with existing food waste management systems, the SOURCE project is supported by Poplar Harca, the social housing provider, the London Borough of Tower Hamlets, and the London Legacy Development Corporation (LLDC).

The project is also working with independent local restaurants, such as Flat Earth Pizzas, and other supply chain partners, to establish a route to market for the locally grown produce. Meanwhile, training and pathways to employment are being designed with the potential for the project to support new green jobs and learning opportunities.

LEAP has sought additional fundraising to expand the project’s scope to three sites in the local area: the original site of the Teviot Estate in London Borough Tower Hamlets, a Hackney primary school linked with seven other schools across Hackney and the LLDC area, and a regeneration site in Newham.

In parallel to this ongoing activity, LEAP is also trialling an experimental rapid micro biodigester system. The system was developed initially at the Teviot Estate, and LEAP has optimised the design for testing at Loughborough University, with the aim of significantly accelerating the processing time for organic waste, while shrinking the system footprint for compact urban spaces.

What were the outcomes?

The additional funding that LEAP sought from the LLDC to scale the technology has now been secured, allowing the SOURCE project to be established at the target sites in Hackney and Newham, with the aspiration of trialling a decentralised network of ‘circular food hubs’ to establish a replicable model that can be scaled horizontally across neighbourhoods.

Implementation and community engagement are ongoing, but projections forecast that SOURCE will help realise a range of mutual benefits for residents, local businesses, and the local authority.

Among these benefits are an increase in recycling rates and a decrease in residual waste from households and businesses due to behaviour change as a result of the engagement and training programme. At the Teviot Estate site alone, it is projected that 2,785m3 biogas and 35m3 compost per annum will be generated from 39 tonnes of food waste and 51 tonnes green waste. Across all three sites the aim is that 8,970m3 biogas and 117m3 compost per annum will be generated from 129 tonnes of food waste and 170 tonnes green waste. By-products will be used to grow food for local consumption, effectively eliminating food and waste miles, while generating revenue to support green training and employment opportunities. Surplus compost will be available for use in local council parks, allotments, and community gardens. Per annum, the project expects to save 11 tonnes of CO2 at the Teviot Estate, and 40.38 tonnes across all three sites — the equivalent of growing 2,019 trees! Over 10 years of the project, taking into account the expected behaviour change across the participating social housing estates and eight primary schools, this saving is estimated at 15,846 tonnes of CO2 equivalent.

Lessons learned and next steps

In designing an accelerated waste processing system, LEAP had to navigate balancing the operational complexity of the process with the capital costs incurred, while taking into consideration energy efficiency and the embodied carbon in the materials chosen. LEAP acknowledges that it has been challenging to find solutions that address all these issues and some compromises had to be made, for example using plastic rather than natural materials for some components due to the biodegradability of the natural materials.

In preparation for the scale-up at the Teviot Estate, LEAP had to learn more in-depth business modelling skills in order to map the economic viability over five years. This valuable exercise informed what to aim for in terms of initial capital outlay and highlighted certain crops that would generate higher revenues to optimise the production side of the business.

LEAP is now looking for land space in London that could be used for food growing, ideally with an initial rent-free period during the set-up phase. It is also seeking organisations and buildings with green space or roof space that are interested in exploring the potential of a net zero carbon and zero waste food production model on-site.

Finally, LEAP is seeking impact investors and/or philanthropic trusts to play a key role in helping scale the project and demonstrate the potential of the circular food model across neighbourhoods in the UK. They are also working in Sub Saharan Africa to establish solar-AD mini-grids to power agri-processing and supply smallholders with low cost biofertilisers and compost. LEAP has delivery partners in the UK, EU, Nigeria, and Malaysia, as well as supply chain, delivery, and manufacturing partners in place.

[1] Excluding loss arising from imports. ReLondon (November 2021), London’s Food Footprint

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