Electrical energy storage refers to a process of converting electrical energy to another form of energy which can be more easily stored, and then converted back to electrical energy again at a later time when it is required. It is possible to store energy in a variety of ways including electromagnetic, electrochemical, chemical, mechanical and thermal mechanisms. Although today, bulk energy storage is dominated by pumped hydro, which accounts for ~99% of global energy storage, it is expected that the vast majority of future storage technology deployment will be in other mechanisms.
The ever increasing penetrations of storage, particularly electrical, on the grid is partly motivated by the desire to increase the penetration of renewable energy sources on the grid. The inherent intermittent nature of renewable sources and the requirement to establish a stable electrical grid system requires new ways to manage these variable inputs to produce a stable output and efficient energy storage would greatly facilitate the mass integration of renewable electricity generation globally, and potentially improve existing grid infrastructures and permit the development of entirely new power architectures, markets, and business models.
Storage challenges exist across four major time scales:
e.g. maintaining the stability of the grid. Real time storage likely requires high power and millisecond response times with storage up to several minutes.
e.g. time-shifting energy within the day, typically shifting peak energy production several hours to late afternoon during peak demand. Intraday storage likely requires reasonably high power and second response times with storage up to 4 hours.
e.g. challenges in interday balancing due to fluctuations in weather patterns. Interday storage likely to require reasonably high power again and quick response times but with storage durations possibly in excess of 24 hours.
e.g. balancing variations in energy demand over the year. Particularly challenging in countries like the UK with significant peak demands during the winter months. Seasonal storage will require moderate power capabilities but massive quantitative of energy are most likely required.
In general, the current generations of storage technologies often struggle to deliver the necessary performance or an acceptable cost to make storage viable. When considering the role of storage in integrating renewables the challenge is to evaluate how the current storage technologies might evolve to meet the demands of performance (e.g. lifetime, efficiency and operational flexibility) and cost, as well as what disruptive new technologies might be possible in the future. This stream of the programme will consider the future potential and likely technical developments in the storage space towards each of the above challenges.