The Geographical Journal

The importance of studying innovation in complex systems: a case study of anaerobic digestion in the UK

By James Suckling, University of Surrey, Claire Hollohan, University of Manchester, and Iain Soutar, University of Exeter

We are placing ever greater burdens upon the natural systems that underpin our societies, economies, and industries. While harvesting and consuming food, water and energy are crucial to satisfying our basic needs, it also has implications for our environment, our economy, and our societal well-being. Food waste, for example, is a hugely important issue, with roughly 30% of all food produce being wasted. This is not only an improper end for embedded water, energy, and land resources, but also a waste management challenge, and if landfilled contributes to climate change.

However, all too often systems are managed in isolation from one another meaning that focusing on, say, the energy system may mean that the resultant impacts on other systems (e.g. water, food) are in danger of being overlooked. Highlighting the need to consider the interdependencies between systems, the concept of the water-energy-food (WEF) nexus has been recognised as an important area for sustainability research. Our recent article in The Geographical Journal explores the process of innovation within the WEF nexus, taking anaerobic digestion (AD) as a case study. It is a processing technology which has a potentially bright future, operating across the WEF nexus to bring many benefits, but is one which is often hampered by siloed thinking.

AD is a natural biological process whereby organic matter is decomposed into methane, carbon dioxide and a nutrient-rich liquid called digestate. Harnessing this process in a controlled environment offers a sustainable alternative to producing gas or electricity by other means e.g. via burning fossil fuels. It also presents an attractive option to manage society’s increasing stream of organic wastes from food, farming, and wastewater treatment, while producing, in the digestate, a potentially-valuable alternative to energy intensive mineral based fertilisers.

Although the biological process is always the same, AD applications are hugely diverse, comprising a diversity of inputs (e.g. food waste, slurries, dedicated crops) and outputs (e.g. biogas, electricity, digestate). This also means that AD has the potential to interact with energy, food and water systems in a multitude of ways. In this study, we interviewed owners and operators of AD plants to better understand the nature of these interactions. We sampled a wide variety plants, encompassing micro-scale community enterprises to large commercial operations; those entirely focused on food waste disposal to those processing a range of feedstocks; those capitalising on energy incentives to those pursuing social and sustainability objectives; those based on farms, and those on dedicated sites; and those which are succeeding as viable enterprises, along with those which are not.

The breadth of AD as an innovation presents both opportunities and obstacles for accelerating its deployment. On one hand, its applicability towards processing a range of inputs and producing a range of products broadens its appeal beyond just energy production. That said, the chief driver of AD in the UK has, to date, been energy policy, particularly support for low carbon electricity and heat production. Though having created a supportive context for AD, the presence of energy subsidies has also constrained further innovation. For example, there are few incentives to explore AD as a tool for organic waste management, land management, social wellbeing, or the intended manufacture of digestate as a product in its own right. Indeed, those plants already operating are constructed to capitalise on the energy rewards, and opportunities may have already been missed, but for the lack of a more diverse support structure. Finally, with fluctuating levels of support from energy incentives, there is uncertainty within the AD industry and the businesses already operating, making new investment unlikely and limiting the scope for diversification of existing plants.

Taking a so-called ‘nexus’ approach is vital if we are interested in ensuring that sustainability transitions are truly sustainable. The nexus approach has emerged in response to calls for research and policy on complex systems to draw on whole-systems perspectives, that is, perspectives that consider the dynamics between multiple innovations and how they coevolve and impact on wider system goals. It demands that we integrate knowledge from multiple disciplines, maintain focus on multiple domains, and apply learning at multiple scales to emphasise the complex set of interconnections between systems. Our findings highlight that if the diverse and bright future envisaged, by some, for AD is to be realised, then its strengths and weaknesses across the WEF nexus must be understood and recognised in research, policy and experimentation, rather than just in terms of the energy sector against which it is currently judged.

About the authors: James Suckling is a Research Fellow at the University of Surrey, Claire Hoolohan is a Research Fellow within the Tyndall Centre for Climate at the University of Manchester, and Iain Soutar is Lecturer in Energy and Environmental Policy at the University of Exeter.   

FAO. (2018). SAVE FOOD: Global Initiative on Food Loss and Waste Reduction. Key Facts on food loss and waste you should know! Retrieved from

Hoolohan C, Soutar I, Suckling J, Druckman A, Larkin A, McLachlan C. Stepping‐up innovations in the water–energy–food nexus: A case study of anaerobic digestion in the UKThe Geographical Journal2018;00:1–15.

Press Association. (2018). Food thrown out by House of Commons doubles in three years. Retrieved from

Watts, J. (2018). Earth’s resources consumed in ever greater destructive volumes. The Guardian, 23rd July 2018. Retrieved from 

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