Exploring the useful energy implications of the global energy transition: a net energy perspective

A global energy transition is urgently needed to phase out fossil fuels and mitigate climate change. Significant financial and energy investments will be needed to decarbonise the energy system, which may reduce the amount of energy available to the rest of society, i.e. the net energy available. Simultaneously, the ongoing process of mineral depletion may also reduce the net energy available by increasing the energy requirements of mining activities. Considering that energy is fundamental to the functioning of human societies, understanding the net energy implications of the energy transition is crucial. I argue that the net energy implications of the energy transition should be analysed through the lens of useful energy. Useful energy is the energy valuable for productive and socially beneficial purposes after conversion in an end-use device (e.g. an engine or a light bulb). To conduct such an analysis, I first develop a Multi-Regional Physical Supply Use Table framework to determine the net energy returns of fossil fuels at the useful stage, both at the global and national levels. Then, this newly developed dataset allows me to conduct the first useful stage-based comparison of the net energy returns of fossil fuels and renewable energy systems. Last, I assess the effects of mineral depletion on both the energy consumption of the mining industry, and on the net energy returns of renewable energy technologies. I find that at the useful stage, the net energy returns of renewable energy systems are likely to be higher than those of fossil fuels, and will only be marginally affected by the effects of mineral depletion. Such results suggest that renewable energy systems have the potential to deliver sufficient net useful energy to provide everyone with decent living standards, provided that net energy is allocated to the appropriate end-uses, and fairly distributed.