The contribution of renewable gases to the decarbonization of energy systems.

Summary The problems linked to global warming imply the need to reduce anthropogenic greenhouse gas emissions. There are three pillars of decarbonization of energy systems, including the use of renewable energies. Renewable energies are often assimilated to electrical energy produced by the sun, the wind, hydraulic energy or biomass. Nevertheless, this electrical energy does not allow for a deep decarbonization of all consumption sectors, whose electrification is difficult. The use of gas produced from these decarbonized energies and called "green gas" can compensate for this by reducing the use of fossil gas. The study of the penetration of these "renewable gases" is the subject of this thesis. To analyze the contribution of green gas to the decarbonization of the energy sectors, the work carried out uses the long-term prospective model POLES (Prospective Outlook on Long-term Energy Systems). In order to represent the green gas production system in detail, we have created a module in this model, linking resources to uses. Thus, the technologies of anaerobic digestion, biomass gasification and the transformation of electricity into gas, called power-to-gas, were modeled and their contributions to the energy consumption of the consumer sectors were estimated. The results show that renewable gas technologies play a role in the energy transition by making it possible to double fossil gas production in the second half of the 21st century. This gas allows the decarbonization of the transport, industry and power generation sectors. Nevertheless, the deployment of these technologies is directly linked to the technical progress expected in the future, as these technologies are for the most part too expensive to be competitive with the use of natural gas at the present time. Moreover, this development is based on the availability of local potential in terms of mobilized biomass resources. Thus, the development trajectories are different, region by region, depending on the local context, both in terms of the available resource and the incentives and political programs put in place to promote the deployment of green gas.