At any moment in time, the consumption of electricity has to be perfectly matched with the generation of electricity. This balance is necessary in all electricity grids to maintain a stable and safe electricity supply. Energy storage can help deal with fluctuations in demand and generation by allowing excess electricity to be 'saved' for periods of higher electricity demand.
Energy storage can support the EU's plans for the Energy Union by helping to ensure energy security and a well-functioning internal market, and helping to bring more carbon-cutting renewables online. By using more energy storage, the EU can decrease its energy imports, improve the efficiency of the energy system, and keep prices low by better integrating variable renewable energy sources.
Energy storage can contribute to better use of renewable energy in the electricity system since it can store energy produced when the conditions for renewable energy are good but demand may be low. This more variable power generation pattern has significantly increased the need for flexibility in the electricity grid. Storage could help balance electricity supply and demand over several different time periods, from fast storage in seconds or minutes to longer storage over days.
Alternatively, renewable electricity can be converted to heat or to hydrogen. Hydrogen can be combined with CO2 to create synthetic methane, or combined with other elements to produce methanol, ammonia, or other chemicals. These can be used to decarbonise other economic sectors, for example in transport as fuel, in industries as material, and in agriculture for fertilisers.
A variety of technologies exist to store electricity, including batteries, compressed air and chemicals, but by far the most common technology to date is pumped hydro storage. The growing need for flexibility in the energy system would benefit from new storage solutions and innovation. Some emerging storage technologies, including batteries and hydrogen, are gradually becoming competitive.
The EU is addressing these new challenges in the energy system by promoting innovation in key technologies and developing suitable market rules. Technological innovation in storage falls under the Horizon 2020 programme and the Strategic Energy Technology Plan.
The technologies related to the use of electricity to produce gas, mainly hydrogen, are managed through a specific programme office, the Fuel Cells and Hydrogen Joint Undertaking.
The energy market has not kept pace with technological progress. Factors slowing the development of energy storage technologies include administrative barriers, limited access to grids, and excessive fees and charges. To initiate a discussion on these topics and on required market rules, DG ENER held a Roundtable on Energy Storage involving a wide range of stakeholders in May 2015. The Commission is working further to develop a more cost-effective energy system that also includes storage solutions. A proposed definition and principles for energy storage have been drafted to support this work.
In February 2017, alongside the Second State of the Energy Union report, the European Commission published a Staff Working Document titled 'Energy storage – the role of electricity '. This document outlines the role of energy storage in relation to electricity, presents the advantages of different technologies and innovative solutions in different contexts, and discusses further possible policy approaches.