Anaerobic Digestion and Sustainability of Agriculture in Brittany: Research at the Crossroads of Geography and Agro-Economics for Assessing the Impact of French Energy Policies

Since the 2010s, farmers in Brittany have developed Biogas units thanks to French authorities’ support for developing agricultural anaerobic digestion. Although anaerobic digestion has been studied for years, few studies have focused on the factors behind its differentiated development on a regional scale. Additionally, while most French studies have focused on farms with a biogas unit, these studies typically do not place them in their socioeconomic and environmental context or assess their impact on other farms. The article addresses these issues by proposing a Comparative Agriculture approach, a transdisciplinary approach at the crossroads of geography and agroeconomics, which allows us to study agricultural development and its consequences. Our approach is spatially and diachronically comparative, systemic and multiscalar. First, results show that anaerobic digestion is developing in agricultural districts with the most significant agronomic potential and on farms that have historically been the best endowed in terms of access to resources, land, and farm equipment. Second, our results reveal that anaerobic digestion can have substantial effects on farms, depending on the size of the unit, down to plot and herd levels. Finally, results indicate that while anaerobic digestion increases the income of project owners, it also leads to widening inequalities between farmers.