The transition to renewable energy sources is a main strategy for deep decarbonization. In many countries, the potentials of dispatchable renewables—such as hydro power, geothermal, or bioenergy—are limited. The renewable energy transition is thus often driven by wind power and solar photovoltaics (PVs). Wind and PVs have characteristic features that become increasingly relevant with growing penetration. In particular, their generation patterns are temporally variable, and the spatial distribution of good wind and solar resources does not necessarily coincide with the historical grid layout. Different technological options are available for integrating increasing shares of variable renewable energy sources, often referred to as flexibility options. These include, but are not limited to, various electricity storage technologies.
So what is the role of electricity storage in the renewable energy transition? In this Commentary, I discuss how three different strands of the literature address this question, summarize a few well-established findings, and provide some intuition on how the role of electricity storage changes with increasing shares of renewables and sector coupling. Using residual load duration curves (RLDCs), which are generated with a stylized open-source model, I illustrate that the main driver for electricity storage deployment shifts when the renewable penetration increases toward 100%, from taking up renewable surplus generation to meeting positive residual load. Flexible sector coupling interacts with the former, but hardly with the latter. Based on this, I suggest promising fields for future research and draw a few high-level policy conclusions.