Energy Storage in Global and Transcontinental Energy Scenarios: A Critical Review

There are a fast growing number of global energy scenarios based on high shares of renewable energy (RE). However, many of them lack comprehensive analyses of energy storage systems. A review of global scenarios reveals that energy storage systems are assessed mainly qualitatively; quantitative assessments of global energy storage demand are scarce. The possible future roles of energy storage systems are plentiful: they can be used in short-term control (e.g. in power grid frequency control), as a medium-term balance mechanism (to shift daily production to meet demand), as long-term storage (seasonal shift), or to substitute grid extensions. Typically, only power storage is considered, if energy storage is assessed at all. Scenario-makers do not always assess the dynamics and synergies of energy storage systems in the power, heat and mobility sectors. To date, publications of the dynamics between continent-wide renewable energy production, transmission grids and energy storage capacities are not numerous. The existing body of research indicates that transmission lines connecting individual countries are regarded as a key component in enabling RE-based, low-cost energy systems. However, various issues could restrain the implementation of proposed grid connections. These barriers could be overcome by partially substituting energy grid reinforcements with energy storage solutions. Furthermore, less storage related curtailment of renewable energy could lead to improved energy system efficiency and cost. Therefore, energy scenarios that capture quantitatively different configurations of international energy exchange and its influence on regional storage systems are needed. High spatial and temporal resolution energy system models are needed to assess scenarios for high share of renewable energy supply and demand for energy storage.