Last month, we examined the extent of food and drink waste and a few ways in which food businesses are tackling the issue. While the scale of food and drink waste has reduced over the last few years, a great deal is still being sent to landfills. Anaerobic digestion (AD) offers one alternative endpoint to food waste.There is waste at every stage of the food production process. The UK produces 110 million tonnes of organic waste, 90 m tonnes of which is agricultural waste such as manure and slurry, 18 m tonnes of food waste and 2 m tonnes of sewage sludge. Currently viewed as a liability, with their correct disposal closely regulated, these wastes can be turned into a valuable resource.The types of organic wastes produced throughout the food processing chain are diverse and they all have a calorific and/or nutrient value. Ideally these nutrients can be returned to the land in a beneficial way and AD is the most efficient way to achieve this. The lifecycle of a food product begins at the farm through to food processing, transport, retail, consumption, and finally to waste, where the life of a product usually ends. With the implementation of AD, this chain is transformed into a loop.AD is a natural process whereby microorganisms break down biodegradable materials such as animal slurry and food waste in the absence of oxygen. The resultant output is digestate: a rich bio-fertiliser that can be used as renewable fertiliser as well as biogas that can be used to generate electricity and heat. The biogas can be used to generate heat and electricity on-site and any excess can be exported to the National Grid and is eligible for various government financial incentives, including Renewable Obligation Certificates (ROCs), Feed-in Tariffs (FiTs) and Renewable Heat Incentive (RHI). As well as ensuring energy security for the business, the renewable energy produced by the AD generates an additional, attractive income stream.The digestate produced by AD negates the need to import other nutrients or soil conditioners. Aside from the financial savings of this “closed loop” process, the rich quality of this natural fertiliser has a range of other benefits. The resultant material will displace the need to use expensive, unsustainable, energy hungry artificial chemical fertilisers, which account for 30% of the carbon footprint of food.In June 2011, the Department for Environment, Food and Rural Affairs (DEFRA), working alongside industry, published their Anaerobic Digestion Strategy and Action Plan, designed to introduce measures to increase energy from waste through anaerobic digestion. In July 2012 DEFRA published a report outlining the progress made since the initial report. There are now more data available on AD as well as advice for businesses that wish to start up an AD system. As of June 2012, there were 78 operational AD plants that treat waste and farm feedstocks in the UK. There is an AD Portal online, bringing together the latest reports, research and other information to assist those interested in starting up or maintaining an AD plant.Funding for AD projects is widely accessible through tax relief and grants for start-up costs. Capital grant schemes are available to support AD plant construction. The Enhanced Capital Allowance Energy scheme provides businesses with enhanced tax relief for investments in equipment that meets published energy-saving criteria. The Waste Reduction Action Plan (WRAP) have a Anaerobic Digestion Loan Fund (ADLF) available to support the development of new AD capacity in England; this was created as a result of DEFRA’s AD Strategy and Action Plan. Businesses can apply for up to £1,000,000 through the WRAP website. There is also the option to send organic waste to be treated by a third party, a number of which offer collections services. These can easily be found online. There is a great deal of advice available online for businesses that are interested in incorporating anaerobic digestion into their business. DEFRA’s AD Strategy and Action Plan is a valuable guidance tool which provides answers to a number of questions about AD.Introducing an anaerobic digestion system can significantly strengthen agri-food operations and has the potential to make primary food producers businesses fully sustainable and even carbon neutral. AD can play an important role in dealing with organic waste and avoiding, through better capture and treatment, the greenhouse gas emissions associated with sending waste to a landfill.
This article first appeared in Food & Drink Technology Magazine in 2014