“One thing is clear: everybody loves storage.” While raising smiles at EURELECTRIC’s workshop on electricity storage last week, this statement does have some truth to it. Experts have noticed a shift in perception over the past few months: storage has suddenly become a topic of much debate. So much so, in fact, that the European Commission is currently preparing an internal strategy paper on storage for Energy Commissioner Günther Oettinger.

But why the sudden interest? After all, the concept of electricity storage is not necessarily new: hydro plants and pumped storage plants have been used to store electricity for decades. By storing water and then releasing it in times of high electricity demand, these traditional storage resources already help to ease imbalances between demand and supply. Beyond providing additional electricity as needed, they also provide a number of services to the electricity system as a whole, helping to manage the power flow and improve the quality of supply.

However, the growth of comparatively small-scale, distributed electricity generation such as wind parks or solar panels is challenging the traditional, “centralised” model of electricity generation. As an ever larger share of generation becomes decentralised, i.e. connected to the mid- or low-voltage distribution grid instead of the high-voltage transmission grid, the electricity system is experiencing a new degree of stress.

Traditional hydro and pumped storage is already helping to integrate more renewable energy. But “decentralised” storage options – like electric cars or batteries – could also be part of the solution. They can enhance the power system’s flexibility by storing electricity when there is a surplus of renewable electricity and releasing it when there is not enough sun or wind to cover demand. Scattered throughout the electricity system rather than at the high-voltage transmission level, decentralised storage solutions could store electricity closer to final consumers, thereby reducing the need for huge investments in upgrading the grid. Moreover, decentralised storage can provide system services much like traditional storage does, with positive effects for market balancing, security of supply and system stability.

Yet decentralised storage raises a host of questions that remain unanswered. What should the market design for storage look like? How should roles and responsibilities be divided among the regulated and competitive segments of the electricity value chain, i.e. distribution and transmission operators on the one hand and electricity generators and suppliers on the other? Which new contracting arrangements are needed between these parties to make decentralised storage possible?

In addition, several participants at the EURELECTRIC workshop were keen to stress that storage as such – be it centralised or decentralised – is not the silver bullet to system flexibility: it is one among many, including flexible back-up, demand side management, smart grids or new interconnections. And despite the growing interest in storage, one basic fact remains: storage technologies are for the most part still in their infancy. Even if a certain technology proves technically viable, it might not be economically viable – or vice versa. Last week’s event was therefore but a starting point for a discussion that will undoubtedly intensify in the months and years to come.