Camille Mesnil: Transforming anaerobic digestion into an ‘energy transition solution’ – The case of the revival of anaerobic digestion in Île-de-France, 1990–2020

This thesis examines the roll-out of anaerobic digestion in the Île-de-France region to shed light on the issues at stake in the schemes being developed in the name of the ‘green city’. Also known as ‘anaerobic digestion’, this process of breaking down organic matter in the absence of air produces a gaseous mixture and digestate, a kind of humus. Its multifunctional nature (waste management, energy production, compost production), its significant flexibility (in terms of technical intensity, inputs and uses) and, above all, the dual environmental promise (as a method of producing so-called renewable energy or as a tool for the circular economy) with which anaerobic digestion can be associated make it a preferred technique for those interested in environmental issues in the broadest sense.

By analysing diverse processes of framing, mobilisation and engagement in the Île-de-France region, as well as the trajectory of different types of arrangements, the thesis demonstrates the primacy of those visions and mechanisms most compatible with the energy system, particularly those associated with major gas networks. It also demonstrates that the interplay between waste management and energy production is not self-evident and is subject to tensions. Beyond these two issues, the thesis highlights the multiple ‘spillover effects’ of the development of anaerobic digestion in environmental terms (water and soil quality, etc.) and socio-economic terms (associated agricultural model).