On the population density limit to variable renewable energy potential

Abstract Renewable energies are expanding rapidly around the globe. In several countries, however, their expansion is being challenged by NIMBY groups and land footprint. In this article, we suggest that indeed a major challenge for renewable energy expansion appears to be tied to land use questions, especially in regions with high population density. Our research finds a strong relationship between population density and renewable energy expansion. The power density of Variable Renewable Energy (VRE) sources, such as wind turbines or photovoltaic panels, is much lower than that of fossil fuels or nuclear power plants, to the extent that land availability seems to be the limiting factor for large scale VRE production. During the last decade, a substantial theoretical effort was dedicated to study the actual power density of VRE, and the available space in order to estimate the limits that land footprint sets on VRE production. On top of the technological, and geographical issues associated with such studies there are somewhat more complicated and less well defined sociological issues related to the willingness of population to live in near proximity to large scale VRE farms. To explore the overall issue of VRE penetration and limitations, the installed VRE capacity data from different countries is examined. It is found that in Germany, with VRE power density of 0.27 W/m2 (2018 data), there is a strong negative correlation between the population density and VRE capacity, dominated by solar power production. We interpret this correlation as an indication that Germany has reached the point where land usage is becoming the limiting factor for installation of new VRE power plants. As Germany is a worldwide leader in VRE production per capita with more than 1 kW/person, we speculate that this sets a universal barrier of 2%-3% on the fractional land area available for VRE production. Crossing this barrier the expansion of the installed VRE capacity is expected to stall. This does not, however, mean that renewable energy expansion will be doomed in countries with high population density. Rather it suggests the need for new approaches — a stronger focus on battery storage technologies, inter-sectoral coupling (renewable energy storage in automobile batteries) and continued investment in efficiency improvements of renewable energy technologies. It may also be a question of how renewable energy develops — enhancing solar on existing built infrastructure (rooftops, siding, and even roads) could help address this issue.