In his 18th book, Vaclav Smil summarizes a lifetime of energy studies in 'Energy at the Crossroads - Global Perspectives and Uncertainties'. The result is a highly accessible book, yet rich in argument.
A chapter on 'energy linkages' looks at the broader energy context (environment, development, war, quality of life, ...). It lies a foundation for a later definition of a necessary energy consumption for essential quality of life requirements.
'Against forecasting' looks back to a century of attempts and often spectacular failures, sometimes by up to an order of magnitude, concluding that the human mind has difficulty assessing the full impact of new technology.
In fossil fuel futures, Smil dares to refer to the Russian-Ukrainian theory of the abyssal abiotic origin of hydrobarbons, calling it 'intriguing' and commenting that it merits more attention that it has received so far in the West.
Before starting the concluding chapter 'possible futures', Smil argues that nuclear energy is likely to have a role, but this role most probably will be limited. Energy efficiency will help as well, but decades of efficiency improvements have seen efficiency gains evaporate for higher demands of energy services. He dares to ask the question of a minimum energy requirements for a decent quality of life, which he estimates at 50-70 GJ/capita, and leaving it to the reader to construct his own scenario's.
In the future energy system, not a single solution will work by itself, and the 'a priori' exclusion of certain options is counterproductive. The path to carbon-free energy is going to take most of the 21st century. The author calls for action of 'complexifying minimalists' rather than 'simplifying maximalists'. We will need a multitude of approaches, flexibility, tolerance and openness.
Finally a personal observation. Sustainable energy may not be an economic or technical problem. The arsenal of solutions is there. At the end of the day, it may be a moral issue.