The POSEIDON project aims to facilitate the use of e-methanol as e-fuel in shipping by demonstrating innovative solutions along the value chain steps: 1. two complementary CO2 valorisation routes – biogenic CO2 from a biogas plant and industrial plant from a lime plant will be investigated, 2. A new hybrid TRL7 power-to-e-methanol technology will be built and demonstrated within a test platform allowing to re-create real case studies conditions, 3. The produced e-fuel will be tested in 2- and 4-stroke engines at testing facilities and in a pilot boat in open sea to confirm its applicability. The project will also pave the way for the future implementation of e-methanol value chains in the port areas of Valencia and Thessaloniki. Communities of practice gathering project partners and external local stakeholders interested in the e-fuel transition will be created. These communities will strengthen collaboration, raise awareness of the potentials and benefits of renewable e-fuels, help members share their vision and discuss requirements and challenges. This will be supported by detailed case study assessment: extensive tests will be performed in a Power-to-X test platform and simulations enabling to evaluate environmental, economic and social mid-term to long-term impacts will be carried out. Market studies and business modelling activities will be done to have a clear view of the deployment potential at EU level. To foster market uptake, an EU deployment roadmap and a replication tool allowing external stakeholders to conduct their own pre-feasibility assessment will be developed. A public project guidebook outlining the main key exploitable results and policy recommendations will be published. To achieve all these results, the project will build upon the wide expertise of its 19 partners. The consortium consists of a well-balanced team of industrial partners (8), research partners (5), business support organisations (2), ports (2), an association and a public agency.