Figure 1 distinguishes various types of actors: (a) funding sources (in green), (b) large industrial entities (red), (c) small and medium-sized enterprises (yellow), (d) research and development actors (universities, research institutions, etc.; blue), and (e) other (networks, associations, etc.; white). The network visualizes actor relations (edges) with publicly funded projects (shown as small gray dots). Here, the node degree (number of connections) of industrial actors (with projects) is represented by the size of their circles to selectively emphasize their relevance. In contrast, other factors (such as the amount of funding) are not stressed in the present visualization. In particular, the representation of R&D actors has been largely simplified here (universities represented only by small blue dots, research institutes grouped by association membership where applicable).
In addition, only actors participating in multiple projects are explicitly shown, while the number of additional entities (only active in that single project) is represented on the marker (numbered circles) for each project where applicable.
We recognize the federal ministry for energy and the economy (BMWi) as the most frequent source of funding for projects related to PEM electrolysis in Germany, while the federal ministry of education and research (BMBF) funded a smaller number of projects of (typically) larger scale as evidenced by the number of related consortial members. On the industrial side, Umicore, FuMa-Tech BWT, Siemens, Greenerity, H-TEC SYSTEMS, and AREVA H2GEN represent frequent participants in funded projects in this topic area and, thus, key players in the field of PEM electrolysis in Germany.
The quality of network analysis critically depends on suitable data processing and the inclusion of complementary data. Since many of the projects (particularly earlier ones) have little to no public presence (project website or similar), there may not be full information on certain projects. It is to be noted that name changes, often driven by mergers and acquisition, may affect the joint recognition of entities, in particular among industrial actors.