Rystad Energy's head of power and gas markets told Montel that 30 GW of battery storage will be needed in the EU by 2030 to maintain the flexibility of the power system and ensure adequate supply.

But by 2050, as coal and gas power plants are phased out, the proportion of more intermittent renewables increases and baseload supply is lost, the amount of energy needed for battery storage is expected to grow exponentially and reach close to 400 GW, added Carlos Torres-Diaz, citing preliminary calculations.

At present, high costs and limited technical capabilities - large batteries can power a power system for no more than four hours - discourage investment in batteries.

"You have to reduce costs and improve technology" to expect to see greater expansion of battery storage, he said.

While the role of energy storage is undoubtedly critical in the energy transition, many uncertainties remain over how green power can be fed and how much storage is needed to help replenish the power system.

Industry experts and lobby groups say the EU needs to set targets and offer incentives that emphasise their key role in the energy transition to encourage increased investment in energy storage and batteries.

Torres-Diaz said: "Setting specific targets for storage capacity, along with some subsidies, would certainly help the industry to develop - as has been done with renewables - to provide greater scope for investment."