What is Food Waste? Turning a Problem into Biogas with Anaerobic Digestion
Roughly one-third of all food produced globally is lost or wasted, amounting to up to 2.5 billion tonnes every year. In the UK alone, about 9.5 million tonnes of food is wasted annually. Food waste isn’t just an ethical or economic issue; it’s a massive environmental one too. When food is wasted, so are all the natural resources used to produce it, and if that waste is simply rotting in landfills, it’s causing other problems which we’ll discuss next.
What Exactly is Food Waste?
Food waste is any food (or part of food) that was originally intended for human consumption but is discarded, lost or left uneaten at some point along the supply chain. Unlike “food loss,” which usually refers to unintentional reductions earlier in farming and processing, food waste often occurs at the retail and consumer level — and is often avoidable.
It can happen at multiple points:
Production & Harvesting: Crops left unharvested in fields due to strict supermarket cosmetic standards or market oversupply.
Processing & Manufacturing: Edible food lost during storage, handling, trimming, or contamination.
Distribution & Retail: Items spoiled during transport or unsold products discarded once they pass “best before” or “use by” dates.
Hospitality & Households: Uneaten meals in restaurants, or food thrown away at home because it spoiled or wasn’t used in time.
In short: if it could have been eaten by people but isn’t, it counts as food waste.
Food Waste vs. Food Loss
It’s important to distinguish between the two:
Food loss typically happens earlier in the chain (farm, storage, processing) and is often due to pests, weather, or technical limits.
Food waste occurs mainly at the retail and consumer level, often linked to behaviour, over-purchasing, or poor planning.
When we talk about anaerobic digestion, we’re usually dealing with food waste already separated from households, retailers or manufacturers.
What the Regulators Say
Different regulatory bodies define food waste in specific terms:
European Union (EU):
Food waste is any food (raw or processed) intended for human consumption that becomes waste within the meaning of the Waste Framework Directive (EU 2019/1597).
United Nations (FAO):
Food loss = reductions in edible mass before retail (production, post-harvest, processing).
Food waste = losses at retail and consumer level (discarding food still fit for consumption).
UK (WRAP/Defra):
Food waste includes both avoidable (e.g., bread thrown away when stale) and unavoidable (e.g., banana peels, bones) material removed from the supply chain for disposal or recovery (including anaerobic digestion).
These definitions matter because food waste must be measured, reported and managed under EU and UK legislation, with a clear priority order:
Prevention (avoid wasting food in the first place),
Redistribution (e.g., surplus food to charities),
Recycling & Recovery (e.g., anaerobic digestion, composting).
Why is Food Waste a Problem?
Wasting food has far-reaching consequences. For one, it’s an environmental concern on a global scale. If all the world’s food waste were counted as its own country, it would be the third-largest emitter of greenhouse gases after China and the US. As food decomposes in landfills, it produces methane, a potent greenhouse gas. In fact, food waste in landfills is responsible for roughly 8% of global greenhouse gas emissions. Methane is over 25 times more potent than CO₂ in trapping heat over a 100-year period, so letting food rot in dumps supercharges climate change.
Beyond climate impacts, there’s the sheer inefficiency and lost opportunity. Millions of tons of edible food are discarded while nearly 800 million people go hungry worldwide. Economically, wasted food represents over a trillion dollars in losses each year when you factor in its production and disposal costs. Environmentally, it’s not just the emissions – it’s also wasted water and land. Food waste piling up in landfills can leach liquids and create local pollution issues, attracting pests and smells more than if that same waste were handled in a controlled way.
Food waste is a major sustainability problem: it fuels climate change, squanders resources and indicates a broken system where perfectly good food isn’t reaching those who need it.
However, there are solutions to rescue the value in this waste. One increasingly popular solution is to turn food waste into useful products like energy and fertilizer – through a natural process of anaerobic digestion.
Anaerobic Digestion: Turning Food Waste into Biogas
Anaerobic digestion is a process that lets us recycle organic waste (like food scraps) into biogas and fertilizer. It’s carried out in special facilities known as anaerobic digesters – essentially large sealed tanks that behave like a giant oxygen-free stomach.
Microorganisms (bacteria) inside the digester break down the food waste in the absence of oxygen, just like bacteria in a cow’s stomach. As they digest the organic material, they release biogas – a mix of methane and carbon dioxide – and leave behind a nutrient-rich residue called digestate.
You can read more about what Anaerobic Digestion is and how it benefits you and the community at BioConstruct New Energy
Key steps in the food waste AD process:
Collection & Preparation:
Food waste is collected from sources (households, restaurants, food factories, etc.) and pre-processed. This often means removing contaminants like plastic packaging or bones. Modern AD plants use depackaging machines and filters to take out bits of plastic, metal, and other non-organics from the food slurry. This step is crucial, if food waste arrives in plastic bin bags, those plastics must be separated out before digestion. The goal is to create a pumpable organic slurry of food waste.
Anaerobic Digestion:
The prepared organic slurry is fed into the digester tanks. These tanks are kept warm and sealed from air. Over days to weeks, naturally occurring bacteria break down the organic matter. This stage is where the magic happens: complex food compounds are converted into simpler compounds, producing biogas in the process. The tanks often gently mix the waste to ensure bacteria have access to all the material. Unlike composting (which needs oxygen), AD’s sealed environment means minimal odour escapes – any smell is contained and treated by filters, making AD facilities far less smelly than, say, open landfills or compost piles.
Biogas Capture & Energy Production:
The biogas (rich in methane) that bubbles up is captured from the top of the digesters. Nothing is wasted – the biogas is piped away to be used as renewable energy. Some AD sites use biogas right on-site in engines or turbines to produce electricity and heat. Others upgrade (purify) the biogas into biomethane – essentially renewable natural gas – which can be injected into the gas grid or used as a vehicle fuel. For example, many UK plants clean up biogas to biomethane quality and pipe it into the national grid as a substitute for fossil gas. Biogas is amazingly versatile: it can light up homes, run generators, or even fuel buses, all from yesterday’s food scraps.
Digestate & Nutrient Recycling:
After the bacteria have done their work, what’s left is a residue called digestate – a thick liquid/fibre mix loaded with nutrients (nitrogen, phosphorus, potassium). Instead of being waste, this digestate is valuable fertilizer. Farmers can use it on fields to enrich soil, replacing chemical fertilizers. By returning these nutrients to the land, AD closes the loop – the nutrients that came from the soil to grow food go back to the soil. This is a big environmental win: it keeps nutrients cycling and reduces the need for energy-intensive synthetic fertilizers. In many cases digestate is further separated into a liquid fertilizer and a fibrous compost-like material, each usable in agriculture or landscaping.
From start to finish, anaerobic digestion transforms “waste” into resources – clean energy in the form of biogas, and soil nutrients in the form of digestate. All of this happens while keeping the process enclosed and controlled, which means less pollution and odour compared to dumping food waste in open air. It’s literally an idea of turning trash into treasure.
Benefits of Anaerobic Digestion for Food Waste
Why go through the trouble of digesting food waste? Because the benefits are substantial – for the environment, the economy, and local communities. Here are some of the key advantages of using AD to treat food waste:
Greenhouse Gas Reduction
AD helps cut emissions in two ways. First, it captures methane that would otherwise escape to the air from rotting waste. Instead of methane leaking unchecked (which would worsen global warming), AD harnesses that gas as fuel. Every tonne of food waste sent to an AD plant is a tonne not producing unchecked landfill methane. Second, when we use the biogas to generate energy, it displaces fossil fuels. For instance, electricity from biogas means less electricity from coal or natural gas. Taken together, these effects are huge for climate benefits. It’s estimated that fully tapping into food waste AD globally could reduce emissions by a significant margin – remember, food waste is ~8% of global emissions, so AD can chip away at that. The UK’s AD sector already has over 1 gigawatt of electrical-equivalent capacity, producing enough green electricity to power more than 1.2 million homes each year, a big contribution to cutting fossil fuel use.
Renewable Energy Production
The biogas from food waste is a renewable energy source available 24/7. Unlike solar or wind, which are intermittent, biogas can be produced and used continuously, providing a stable source of power. AD plants often export electricity to the grid or supply heat to local industries. Or, as noted, they produce biomethane for gas grids and transport fuel. This not only provides local, clean energy but also improves energy security (less reliance on imported fuels). Some large facilities generate millions of cubic meters of biomethane – for example, an AD plant processing ~100 tonnes of food waste per day can produce enough energy to power 800–1,400 homes for a year. In an era of net-zero targets, this is energy we can’t afford to leave untapped.
Waste Management & Landfill Diversion
Every bit of food waste sent to AD is a bit not sent to landfill or incineration. This eases the burden on landfills (which are reaching capacity in many regions) and avoids the downsides of incinerating wet food (food waste is high in water, making it inefficient to burn). Recycling waste into biogas and fertilizer is a much higher-value use. The UK generates about 9.5 million tonnes of food waste annually.imagine if most of that could be processed via AD instead of rotting. AD also tends to be more localized – you can have regional plants dealing with local waste, whereas landfills often are massive and distant. Using AD means fewer long haul garbage trucks and a more circular approach to handling organics. In fact, many local councils are looking at AD as a way to meet recycling targets and to cut waste disposal costs (landfill taxes and gate fees for dumping are hefty, whereas food waste can be a feedstock with economic value).
Nutrient Recycling & Soil Health
Unlike landfill or incineration, AD recovers the nutrients in food waste. The digestate output is rich in nitrogen, phosphorus and potassium which are all essential for plant growth. When farmers use digestate on fields, they reduce their need for synthetic fertilizers. This has a few benefits: it saves money for farmers, it reduces the environmental footprint of fertilizer manufacturing, and it helps improve soil quality by adding organic matter. Farmers have reported improved soil structure and fertility after repeated use of digestate. Essentially, AD turns yesterday’s food scraps into tomorrow’s plant food. By returning nutrients to the soil, we support sustainable agriculture and keep that nutrient cycle going, rather than letting nutrients go to waste in a dump.
Odour and Hygiene Control
Pungent odors and vermin are common complaints around food waste bins and landfills. AD plants, however, are closed systems. Trucks delivering food waste typically unload inside enclosed reception halls with air filtration. The digestion itself happens in sealed tanks. This means odour is managed, a well-run AD facility can reduce smells compared to simply piling up waste. Many plants use biofilters and scrubbers on their exhaust air. Also, because the process is enclosed and the waste is processed relatively quickly, there’s less chance for pests (like rats or flies) to infest. Overall, AD offers a cleaner and more sanitary way of handling large volumes of organic waste than open-air dumps or even open compost windrows.
Local Economic Benefits
The anaerobic digestion and biogas industry brings jobs and investment. Building and operating AD plants requires engineers, construction workers, operators, drivers, and maintenance crews. In the UK, the AD industry supports thousands of jobs – from plant operators to lab technicians monitoring the digestion process. Each new facility often represents tens of millions of pounds of investment, much of which goes into local economies (for construction, feedstock supply contracts, etc.). On a smaller scale, businesses that produce a lot of food waste (say, food manufacturers or supermarkets) can save money by sending their waste to AD instead of paying landfill fees – and some even earn income if an AD plant pays for high-energy content waste. Plus, communities get a boost from having local renewable energy infrastructure – sometimes AD plants even offer community benefit funds or cheaper energy to nearby users.
Environmental and Community Gains
By preventing pollution from unmanaged waste, AD helps protect local wildlife and habitats. No leachate seeping into groundwater, no uncontrolled gas emissions. Many AD projects also incorporate environmental enhancements – for example, planting trees or hedges around the site, creating wildlife corridors, or using digestate to improve degraded lands. Instead of a smelly landfill that nobody wants in their backyard, communities are finding that a well-run AD plant can be a relatively quiet, low-profile neighbour – typically tanks are not tall and sites are screened with greenery. And because these plants deal mostly with waste from the vicinity (like a county or region), they fit into a circular economy model – local waste creating local energy and local fertilizer, benefiting the same community that produced the waste.
Anaerobic digestion turns the food waste problem into an opportunity by producing green energy, reducing pollution and fostering circular use of resources. It’s not often we get a win-win like this, where one solution addresses waste management, climate change, energy and agriculture together. AD is doing exactly that for cities and rural areas alike.
Future Outlook: Food Waste as a Biogas Resource
The push to utilise food waste in anaerobic digestion is only getting stronger. Governments and industries are increasingly recognising that sending food waste to landfill or incineration is unsustainable, both environmentally and economically, and are implementing policies to change that. In the UK, a major change is on the horizon: by 2026, all households in England will be required to have weekly separate food waste collections. This is part of a nationwide effort (“Simpler Recycling”) to standardise waste separation.
This means a significant increase in source-separated food waste being available for AD plants. Instead of throwing banana peels and plate scraps into the general rubbish, tens of millions of people will have a food caddy collected weekly and sent for treatment. This will boost feedstock for AD facilities dramatically, providing a steady supply of material for biogas production. Similar policies are being discussed in many other countries, from mandating large restaurants to separate food waste, to banning food waste from landfills outright (as already done in some EU nations).
All these efforts point to one thing: the anaerobic digestion industry is poised for growth. We’ll likely see many more facilities like the ones described in the case studies being built, and existing ones expanded, to handle the influx of organic material. Innovation is also on the rise – for instance, better pre-treatment technologies to deal with packaged food waste, more efficient digesters that can extract more biogas per tonne, and improvements in biogas upgrading and storage. There’s also an increasing trend of integrating food waste digestion with other systems: co-digestion in wastewater treatment plants (adding food waste into sewage sludge digesters to boost biogas output), or farm-based digesters taking in community food waste alongside manure. These hybrid approaches can make AD even more economical and widespread.
From an industry perspective, the convergence of waste management and energy production is creating new business models. We’re seeing collaborations between waste companies, energy utilities, and technology providers. Investors are increasingly interested in biogas as part of the renewable energy portfolio. And importantly, public awareness is growing: people are starting to realise that biogas is just as “green” as solar or wind and it directly addresses a waste problem they encounter every day.
Many AD plants now run visitor centres or educational programmes to show communities how their apple cores and coffee grounds become electricity and fertiliser. This helps build local support for new projects, a far cry from the old “not in my backyard” stance towards waste facilities. After all, a modern biogas plant on the edge of town sounds a lot better than a huge new landfill.
Key Takeaways
Food waste isn’t just rubbish, it’s a valuable resource waiting to be used. Through anaerobic digestion, we can take the problem of wasted food and turn it into solutions: renewable biogas, green power, and organic fertiliser. Instead of emitting methane from landfills, we capture that methane to fuel homes and vehicles. Instead of depleting soils, we return nutrients via digestate. The examples from the biogas industry, including projects by BIOCON Group’s companies, show that this isn’t theoretical – it’s happening now at industrial scales, with tremendous success.
For operators and investors in the waste and energy sector, the message is clear: diverting food waste to AD is a win–win strategy for sustainability and profitability. Communities benefit through reduced waste, less odour, local jobs, and clean energy. Businesses can turn disposal costs into revenue. And globally, scaling up AD for food waste is one piece of the puzzle in combating climate change and building a circular economy.
Finally, if you’re reading this as someone interested in anaerobic digestion – whether you manage a food company looking to cut waste costs, a local authority planner, or a renewable energy enthusiast, consider how biogas from food waste could play a role in your world. The potential is enormous and largely untapped.
Your complete AD partner
To explore it further or get expert advice on starting a project, feel free to reach out to our team. At the BIOCON Group we have a deep expertise across the entire AD project lifecycle, from initial feasibility and planning to construction, operation, and maintenance. We’re passionate about turning waste problems into energy solutions.
