When, in the 1990s, the first visionaries and idealists began installing exorbitantly expensive and inefficient solar panels on their roofs, the scientific community and the energy industry were overwhelmingly in agreement that photovoltaics could never become a technology capable of making a significant contribution to the electricity supply of industrialised nations. In contrast, major government funding initiatives in the 1970s, the 1990s, and again today have proclaimed the advent of a hydrogen economy - a vision that has yet to become a reality. Similarly, despite decades of funding programs worth billions, nuclear fusion has remained nothing more than a vision. 

Visions for the energy sector have been shaping public discourse long before the energy transition. Which visions are realistic? What factors determine the economic and technical feasibility of new technologies? And what roles do society, investors, and policymakers play in this context? 

Drawing on historical examples, the lecture examines the fate of many progressive ideas, discusses the challenging conditions for innovation in the energy sector, and attempts to contextualize current visions for the future of our energy supply.