‘Flow batteries’ could provide frequency response in the UK for the first time ever, as a modestly sized solar-plus-storage system has been pre-qualified into National Grid’s dynamic firm frequency response (dFFR) market.

Last week energy storage technology provider and system integrator RedT - which prefers the description ‘flow machines’ for its vanadium redox flow, long duration devices - and aggregator / energy data and technology specialist Open Energi achieved pre-qualification status for a 300kWh flow machine installed at an industrial site in Dorset, southern England. The device is coupled with a solar installation with a peak generation capacity of 250kW.

The machine has been integrated with Open Energi’s Dynamic Demand platform, and Open will be tasked with optimising the asset’s performance and revenue generation.

RedT said that flow machine technology was well suited to providing grid services due to their ability to withstand large numbers of daily cycles. Flow machine technology doesn’t degrade like other battery storage technologies, such as lithium-ion.

Scott McGregor, chief executive at RedT, said that there was common misperception that flow machines are incapable of providing fast frequency response services, with the technology more commonly associated with long-duration energy storage.

“This achievement demonstrates the ability of non-degrading, heavy-cycling energy storage technologies such as flow machines to provide much needed flexibility to the network. This is a key opportunity for investors, energy managers and business owners to deploy 25-year energy storage infrastructure, at their sites – an essential piece of the puzzle our country must solve in order to achieve net-zero by 2050,” he said.

The pre-qualification capped off a productive week for redT, which also celebrated agreeing outline terms on a merger with fellow vanadium redox flow battery outfit Avalon.

In comments made to Energy-Storage.news around the merger announcement, McGregor went on to say that "lithium and flow are complementary technologies, doing different things."

"Lithium is a very cheap power technology which is good for certain applications but the future of energy storage will be heavy cycling energy storage. So, heavy duty, infrastructure energy storage: which is what flow is."

Speaking just before the pre-qualification was publicised, McGregor said that the wider market for flow and other long duration energy storage technologies will open up as "flow gets out and proves itself as a solution. You can open up many more energy storage applications that require much harder working assets that lithium can’t do."

"I actually say lithium and flow are complementary technologies, doing different things," McGregor said, with the company's technology recently deployed in a lithium-flow grid-scale hybrid project at Monash University, Australia.