The UK will need batteries that last four-times longer to balance supply and demand in a system that’s becoming more driven by swings in renewable power generation.

Now, Britain’s grid operator is incentivizing short-duration batteries of about two-hours, that won’t be suitable in future, according to a report by Balance Power Group Ltd. Energy storage of eight-hours will be needed to help supply power to the grid during periods of low wind.

The risk is that the capacity will have to be built twice, replacing shorter duration projects, which will mean even longer queues for grid connections. National Grid Plc and regulator Ofgem should support bigger projects, offering developers quicker connection dates and financial support in exchange, according to the report.

“Two-hour electricity storage systems will likely produce a sub-optimal outcome due to a larger than necessary volume of grid connections being required,” Balance Power said in the report. “This will likely add extra costs and time delays to connect individual electricity storage projects to the grid with the knock-on impact of making electricity more expensive for consumers in the interim.”

The UK wants to build 50 gigawatts offshore wind by 2030 but needs a stable technology as back up for periods when it’s not windy. To achieve the goal of having a carbon-free electricity grid by 2035, storage is needed to take renewable electricity when it’s abundant and discharge it when it is scarce. Reducing demand during still periods will also be a crucial way of balancing the network.

“To lose this momentum due to the significant gridlocks we’re experiencing will have serious, long-term effects on our ability to reach and sustain a net zero grid,” said Phil Thompson, chief executive officer of Balance Power.