With the technology breakthroughs in solar PV, electrification of transport, batteries and other green technologies, there is little doubt that the longer-term future of energy will be green and clean.  However, stating that the future of energy also will be lean is less recognized.  On the contrary, many people have focused on an expected growth of demand for materials, with lithium for batteries and copper for electrification being two examples.  However, a holistic analysis of the future energy system shows that the global flow of materials will be drastically reduced in a future electrified society. I will share some evidence for this development.