By David Newman, President of the World Biogas Association

Ahead of the launch of a new international report by the World Biogas Association (WBA) and the C40 Cities Food, Water and Waste Programme on urban food waste management, WBA President David Newman sets out why it’s critical for cities around the world to manage their food waste sustainably.

 The last ten years have seen a marked increase in the recognition of food waste as a critical global environmental issue. Not only has the issue of wasted food become an ethical one in a world where approximately 800 million people suffer from hunger, but the enormous environmental impacts of producing food that is then discarded can no longer be overlooked. As the global population grows and urbanisation increases, more food is being produced and wasted, creating severe environmental and public-health consequences particularly in urban areas, which are projected to home as much as 70% of the global population by 2050.

The challenge and opportunity

Poor management of food waste causes the loss of natural resources, human health issues, pollution of rivers and seas, the generation of methane emissions from dumps and landfills, and a missed opportunity to recover valuable energy, organic matter, nutrients and water contained in food waste. Taken together, the scale of these combined impacts means that meeting the Paris Agreement and the UN Sustainable Development Goals will simply not be possible without sustainable management of urban food waste.

Cities around the world are expressing a need for help on food waste as one of the largest environmental problems they face. As one of the low-hanging fruits available to reduce greenhouse gas emissions globally, collecting and treating food waste does, however, create opportunities as well as solving problems. Our calculations show, for example, that treating the world’s 1.6 bn tonnes of food waste would be equivalent to taking all the cars in the EU off the road.

With countries and cities racing to make their Nationally Determined Contributions under the Paris Agreement by 2020, there’s no time to lose in communicating the importance and opportunities of this issue.

The best treatment

There are a number of different ways of treating food waste, but by far the best from an environmental point of view is anaerobic digestion (AD), a natural process that uses microbes to break down the food waste and produce a renewable biogas (which can then be used to produce heat or electricity) and a nutrient-rich digestate by-product that can be used as an organic fertiliser.

The AD process also helps reduce volumes of waste and odours from waste, and closes the loop through returning digestate back to soil. The particular contribution of digestate is greatly underrated, with soil quality not yet receiving the legislative attention it deserves. We have seen in arid areas of the world how digestate contributes nutrients and moisture to soil, enabling a significant increase in yields, farm incomes, stability of communities, and hunger and poverty reduction.

At the moment, the costs of implementing AD systems remain relatively high, making it a difficult choice for treating food waste in low-income countries in particular. However, costs are gradually falling, and there’s a strong focus in the biogas industry to bring about a step change in the efficiency of AD processes to help support this trend.

What cities and municipalities can do

Systems for collecting and treating food waste are currently highly dependent on local circumstances. There are no technical barriers to implementing effective food waste collection and treatment – what is required is investment and political will to do the right thing. The climate change and waste management gains made from separate collection of food waste far outweigh the costs, but the political will to raise the initial cost to achieve those benefits has yet to be shown in many countries.

Cities that do have separate collections need to look at the quality of their collection systems to reduce contamination of food waste to ensure that clean materials are returned to the soil through digestate. As with all solutions, it’s important that AD is implemented intelligently, with a good understanding of local circumstances such as feedstocks, technical capacity, and legislative drivers; this will help ensure that it can deliver maximum return on investment.