Population-Density Bounds for 100% Domestic Renewable Energy Generation

The long-running discussion on the global theoretical and practical potential of renewable energy is strongly affected by the size and connectivity of power networks. Small regional and national networks driven predominantly by intermittent and variable energy sources will require significantly more back-up power than continental networks containing a variety of weather zones. Thus, large networks will require less back-up but this comes with the drawback that some nations or regions rely on import from others. For example, in Europe in 2022, energy dependence on gas imports from Russia led to energy shortages and escalating prices. In this work, we estimate the limits of primary energy supply based on renewables, mainly solar photovoltaic (PV) sources and wind, in this setting. Taking as a starting point an average of 14 European countries, we find the mean energy consumption per unit time in what we argue is sufficient and necessary power per capita to maintain a sustainable life. The required energy generation is then translated into an area of energy production that, together with estimated area requirements for biological diversity, food, and infrastructure, constitutes a given fraction of the land area. When compared with typical human population densities, we find that before reaching one person per hectare, the area requirements exceed what is available. The results support the part of the scientific community that claims that a 100% renewable global power supply is unrealistic, especially as the world population steadily grows toward $10\times {10}^9$ people.