The report, published by Eurelectric and consultancy AFRY, estimates that deploying 1GW of LDES could reduce annual variable system operating costs by €150–250mn. The potential savings rise as larger volumes of wind and solar power are connected to electricity networks.

LDES refers to technologies capable of storing electricity for eight hours or more. These include pumped hydro storage, flow batteries, compressed air energy storage and liquid air energy storage. The analysis focuses on emerging storage technologies rather than pumped hydro, which is already widely deployed across Europe.

According to the report, LDES market overview – what is the outlook for innovative LDES in Europe?, higher levels of wind and solar generation are creating more periods of surplus electricity production alongside periods when renewable output falls short of demand. LDES can help address both challenges by storing electricity when supply is abundant and releasing it when it is needed.

Researchers found that storage can reduce renewables curtailment, ease network congestion and lower balancing costs. It can also reduce reliance on flexible fossil fuel generation during periods of lower renewable output.

Kristian Ruby, Secretary General of Eurelectric, said the emergence of a stronger commercial case for long-duration storage reflected the growing need for flexibility across Europe’s electricity system. ‘Europe’s energy transition needs technologies that can cover the increasing need for flexibility in the power system. It is encouraging that a business case is beginning to emerge for innovative long-duration energy storage with substantial system benefits: less curtailment, lower operating costs, reduced congestion and greater security of supply,’ he commented.

The analysis found that LDES addressed different challenges in different markets. In some countries, revenue opportunities are driven primarily by energy trading, allowing operators to store electricity when prices are low and release it when prices rise. Elsewhere, the main value comes from helping system operators manage congestion and maintain grid stability.

The findings come as policymakers seek ways to integrate growing volumes of renewable generation while maintaining reliability and controlling system costs.

In the UK, the energy regulator Ofgem is assessing projects under its cap-and-floor support scheme for LDES, which aims to balance the power system. Last year, Ofgem confirmed that 77 projects had progressed to the final assessment stage of the scheme, covering technologies including flow batteries, lithium-ion batteries, compressed air energy storage and pumped hydro.

Investment in large-scale storage projects is also gathering pace. In September 2025, Fidra Energy reached financial close on the 1.4GW Thorpe Marsh battery energy storage project in South Yorkshire, which is expected to begin operating in mid-2027. More recently, in May this year Invinity Energy Systems completed the delivery of 20.7MWh of vanadium flow batteries (VFB) to the Copwood VFB Energy Hub at a site in Uckfield in East Sussex, which is set to become Europe’s largest VFB installation when it enters service later this year. The project pairs 90 VFBs, made in Scotland, with a 3MW solar array.