Renewable Energy Hamburg is a cluster organisation with approximately 240 members from the renewable energy and hydrogen sector in Hamburg and Northern Germany. We interconnect partners from four different branches: the industry, R&D, politics and civil society. Hence, Renewable Energy Hamburg cooperates with many actors involved in the green energy sector, such as energy producers, manufacturers, service providers and universities. By facilitating regional, national and international networking, by hosting high-quality conferences and by realizing collaborative projects within the European Union, the cluster serves as powerful renewable energies promotor, advocating also the interlinking of energy sectors in the Metropolitan Region of Hamburg and beyond. Hamburg is considered a central hub for the sustainable energy transition in Germany. Not only does Hamburg have a workforce of approximately 25,000 employees working in the green energy sector. In addition, the harbour city benefits from an excellent research environment and is home base for numerous worldwide leading wind energy firms. Consequently, Hamburg represents a competence centre for renewable energy development and the coupling of the electricity, heat and mobility sectors.