Recent research suggests that the effects of climate change are already tangible, making the requirement for net zero more pressing than ever. Part of the solution for net zero will be geo-energy technologies in the North Sea, including offshore wind, blue and green hydrogen, and carbon capture and storage. These new technologies will interact with each other in the potentially-sensitive subsurface, seabed and water column. The project will assess the environmental sustainability of these technologies combined, for selected test areas of the UK offshore, and will develop solutions to make sure that the technology and infrastructure of the offshore energy transition, works well, is efficient, and does not harm the environment. Work package 1 focuses on the security and viability of industrial scale subsurface offshore hydrogen storage and carbon dioxide storage and investigates how the two might interact, and how best to make decisions about when to use storage space for hydrogen, and when for carbon dioxide. Work package 2 focuses on the characteristics of the sea bed and water column above the storage sites in the geology, and the effects of gas or fluid release from geological storage on the environment, and the environmental interactions of other offshore energy infrastructure like windfarms and cables. Work package 3 will focus on the social implications of an offshore energy transition, evaluating the risks and benefits of different technological scenarios to ecosystem services (the natural benefits that we get from the ocean, like fisheries), and it will look for net benefits where combinations of technologies provide extra environmental or efficiency improvements. Work package 4 will work with other WPs to ensure a fully integrated project, bringing together outputs from each work package into a usable form to support the decisions that stakeholders like the Oil and Gas Authority, Crown Estate, National Grid, and operators like Equinor, might make in the future.