In the most recent posts last year, I looked in some detail at what the energy costs of energy supply imply for global-scale transition from fossil fuels to (mostly) renewable energy (RE) sources. The modelling presented there highlighted the importance of taking a dynamic view of transition – rather than just looking at the start and end states. If we’re serious about identifying feasible transition pathways, this type of approach has an important role to play. It’s reassuring to see that more significant effort is starting to be made in this area.

One reason this has been slow to gain traction is the idea that renewable energy sources are so abundant as to be without practical limits. It’s a popular and compelling story, but unfortunately, also one that obscures as much as it reveals. Here, I’ll explain why, and set out the detailed case for why we are much better served by thinking in terms of the practically realisable potential for renewable energy, rather than the raw physical flows. At the heart of this is a basic insight, expressed in a simple aphorism: ‘each joule of energy is not equal’. Continue reading →