Producing biogas from energy cover crops in France: Potential production and agro-environmental impacts

Anaerobic digestion produces renewable energy such as biogas to replace fossil one. Cover crops are an interesting resource without competing for food production while producing some ecosystem services. We assessed the potential of cover crops to produce energy in France at high resolution and their agro-environmental impacts. We used a modelling chain of four models to simulate the cropping systems and the biogas plant. We designed and simulated over 30 years the baseline and three scenarios: (i) multi-service cover crops, (ii) energy cover crop insertion and (iii) energy cover crop extension. Over the 13.9 Mha simulated, it modified 11.0 Mha for the two formers and 13.6 Mha for the latter, representing 4.0–6.8 Mha.yr −1 against 1.6 in the baseline. Cover crop biomass could provide 4.4–31.1 Mt.yr −1 , mainly based on winter cover crops, or 17–115 TWh.yr −1 of gas (4–27% of the consumption in 2021). Winter cover crops reduced spring crop yields, between 7% and 17%. The greenhouse gas balance was improved in all scenarios, despite higher N 2 O emissions and for the energy cover crops, higher mineral fertilizer consumption and volatilization. This positive effect was obtained thanks to carbon storage and fossil gas substitution, the latter having a stronger impact. Finally, drainage was reduced while irrigation was increased while nitrate leaching was surprisingly not much impacted. Cover crops are a promising resource to combine renewable energy production and positive environmental impacts as long as they are applied to avoid food competition and water consumption impact.