This discussion paper examines the emerging energy landscape from a physically grounded perspective. It argues that industrial societies are now operating two non-green energy systems in parallel: a long-established, low-material-intensity system based on fossil fuels, hydropower and nuclear energy, and a rapidly expanding, high-material-intensity mineral-based system built on solar panels, wind turbines, batteries and mineral-intensive grids, commonly presented as “green” or “renewable”. The fossil system concentrates its waste in the atmosphere as greenhouse gases, while the mineral-based system concentrates its waste in the geosphere through tailings, waste rock, chemical pollution and long-lived contamination. The paper proposes Sufficiency as the goal and Repeatability Across Generations as the main means, introducing Time Step 3 – Repeatability Across Generations as a new way to evaluate whether energy systems, infrastructures and industrial pathways can still be operated 100–500 years from now without exhausting resources, breaching planetary boundaries or damaging ecosystems beyond recovery. It highlights the material intensity and geopolitical asymmetries of the mineral-based system, the central role of biodiversity and living ecosystems, and the need for a smaller, more robust energy system with lower throughput and longer lifetimes. Framed in this way, sustainability shifts from distant targets, willingness-to-pay debates and political bargaining to a legal and institutional boundary condition: only systems that can credibly be maintained for 100–500 years within ecological limits should qualify as “sustainable”. Time Step 3 is developed as a governance approach that can be embedded in laws, standards, permitting rules and corporate obligations – including company law – and, while the paper focuses on energy and related infrastructures, the underlying concept can in principle be extended to a wide range of goods, services and industrial activities.
Ivar Backlund (2026) studied this question.