Geo-energies, such as geothermal energy, CO2 storage and underground energy storage, have a great potential to contribute to meet the Paris Agreement targets on climate change. Yet, their deployment has been hindered by a lack of a full understanding of the processes that are induced in the subsurface by large-scale fluid injection/extraction. The various processes involved (e.g., fluid flow, geomechanical, geochemical and thermal effects) imply complex interactions that cannot be predicted without considering the dominant coupled processes, which is rarely done. As a result, some early geo-energy projects have occasionally developed unpredicted consequences, such as felt and damaging induced earthquakes, gas leakage and aquifer contamination, dampening public perception on geo-energies. SMILE aims at overcoming these challenges in developing geo-energy solutions by training a new generation of young researchers that will become experts in understanding and predicting coupled processes. Thus, they will be capable of proposing innovative solutions for the successful deployment of subsurface low-carbon energy sources while protecting groundwater and related ecosystems. To achieve this ambitious goal, the early-stage researchers will be exposed to an interdisciplinary training on experimental, mathematical and numerical modelling of coupled processes, upscaling techniques and ground deformation monitoring using field data from highly instrumented pilot tests and industrial sites. The training in SMILE has been designed by both academic and industrial partners to train competitive researchers with both technical-scientific and transferable skills to enhance their employability in academia, industry and public sector. The outputs of the project will be largely disseminated. Outreach to society will be achieved through a conspicuous series of initiatives. SMILE will make a significant contribution to the societal challenges of securing clean and low-carbon energy sources.