Climate change means that we need to look for solutions to decarbonise human activities, but implementing these solutions at local level may open up other threats. With regard to the development of hydrogen as a substitute for hydrocarbons, are the benefits and risks of industrial projects so clear that they are self-evident? Or is the path to their realisation being altered to deal with multiple risks? Some risks are put forward as a source of legitimacy (such as the climate risk to be combated), others as potential obstacles to the project (such as the technological risks to be prevented in the production and consumption areas). Similarly, the course of the project is shaped by opportunities such as changes in public policy incentives, debt relief through inflation, public support for a sense of climate action and for reindustrialisation, etc. It is this iterative design movement in a game of sometimes opposing forces that this research programme aims to shed light on by examining an industrial project with high territorial stakes that has been seized and is in the process of being formulated. To this end, it proposes to integrate the analytical capacities of the environmental sciences and the social sciences to determine the value of the risks and opportunities and to track whether or not they are taken into account by the players involved. Among these risks and opportunities, particular attention will be paid to the contradictory effects of the use of hydrogen on the climate and on air quality: hydrogen produced by electrolysis avoids the mobilisation of methane, which has a greenhouse effect, but the fugacity of hydrogen represents a potential risk of leaks into the atmosphere, which indirectly cause an additional greenhouse effect, an increase in tropospheric ozone pollution and the destruction of the stratospheric ozone layer that protects living organisms from the sun's harmful UV rays. On the socio-political side, there are similar ambivalences in favour of the project (as a source of new activity in the face of the limitation of carbon energies, as a source of revenue for local authorities, as a demonstration of collective mobilisation against the environmental crisis, etc.) and against it (in the face of financial risks, health risks, conflicts over use of the land involved, failure to take citizens into account in socio-technical decisions, lack of transparency in the management of public money, etc.).

The social sciences know that socio-technical controversies, public support and the public policy measures governing the energy transition all influence the trajectory of such projects, but the repertoires in which these risks and opportunities are articulated at local level and in their interactions with national and international levels are still poorly understood. Monitoring the project as closely as possible to the area during its definition phase should help to shed light on these issues and, in particular, to see how the rhetoric of promise in various fields echoes the rhetoric of injunction on environmental issues.