Ofgem has provisionally backed 16 long-duration energy storage projects from SSE PLC (LSE:SSE), Invinity Energy Systems PLC (AIM:IES, OTCQX:IESVF, AQSE:IES) and other private developers, as this week's heatwave underlined the need for technologies that can store renewable power for days or weeks rather than hours.
Low wind speeds and soaring electricity demand forced gas plants to provide more than half of Britain's electricity on peak days, while grid constraints meant some available renewable generation could not be used and additional power had to be imported from abroad.
The energy regulator said the projects had passed an eligibility assessment and would now move into the next phase of the selection process, with stakeholder consultation before final decisions are made.
The portfolio includes four technologies: pumped storage hydro, compressed air energy storage, lithium-ion batteries and vanadium redox flow batteries.
The projects are spread across Scotland and England, with one vanadium redox flow battery project proposed in north Wales.
Long-duration electricity storage refers to systems capable of storing and releasing power for at least eight hours. The technology is seen as increasingly important as Britain adds more wind and solar generation, whose output can fluctuate depending on weather conditions.
Ofgem said the selected portfolio is expected to reduce costs by easing pressure on transmission and distribution networks and limiting the need for expensive grid upgrades or constraint payments, which are incurred when renewable generators are paid to reduce output because the network cannot absorb the electricity.
The regulator will now seek views from industry and other stakeholders on the provisional selections before deciding which projects will receive support under the scheme.
The announcement comes as Britain's power system has come under strain during this week's heatwave.
A combination of soaring electricity demand and very low wind speeds forced gas-fired generation to provide more than half of the country's electricity on peak days, while grid constraints meant some renewable generation was curtailed and additional power was imported through international interconnectors.
It has highlighted the UK's shortage of long-duration energy storage. Lithium-ion batteries have expanded rapidly but typically store only one or two hours of electricity.
The Climate Change Committee has said flexible storage capacity will need to more than triple by 2030 to support a renewables-led power system and reduce reliance on gas during periods of weak wind generation.
Portfolio of 16 projects
The portfolio of 16 projects spans a range of technologies: three pumped hydro projects, one compressed air storage scheme and 12 long-duration battery projects, including 11 lithium-ion facilities and one vanadium flow battery development.
Pumped hydro, compressed air and long-duration batteries are capable of storing electricity for between eight and 32 hours.
The biggest schemes include SSE's 1.4GW Coire Glas pumped hydro project and Gilkes Energy's 1.8GW Earba project in Scotland, while private developers including Field, Statera and Zenobē are behind several of the battery storage projects.
NameTechnologyRegionLoch Kemp StoragePumped hydroN ScotlandCoire GlasPumped hydroN ScotlandTeesCAESCompressed air NE EnglandEarba PSHPumped hydroN ScotlandField NethertonLi-ion BESSN ScotlandField New DeerLi-ion BESSN ScotlandField RigifaLi-ion BESSN ScotlandField FyrishLi-ion BESSN ScotlandField Long StrattonLi-ion BESSE EnglandEast Claydon StorageLi-ion BESSE EnglandOcker Hill BESSLi-ion BESSW MidlandsSundon StorageLi-ion BESSE EnglandDrakelow (Innova)Li-ion BESSW MidlandsFrontier LegacyVFB/ZnN WalesSpringwellLi-ion BESSE MidlandsThornton BESS 2Li-ion BESSE Midlands
SSE's Coire Glas project on the shores of Loch Lochy in the Scottish Highlands between Fort William and Inverness would be Britain's largest electricity storage facility, capable of storing at least 45GWh of energy and generating power continuously for more than 30 hours.
The proposed 1.4GW pumped hydro scheme on its own would effectively double the UK's existing electricity storage capacity if it goes ahead.
Pumped storage hydro has an assumed economic life of 40 years, Ofgem said, compared to 25 years for Li-ion batteries and 30 years for the vanadium flow/zinc battery.
Vanadium flow specialist Invinity Energy Systems hailed the inclusion of Frontier Power's 'Legacy' project on the list, which has a total capacity of 520 MWh and is currently expected to be split approximately equally between VFB and zinc-halide battery technology.
The AIM-listed company said it was a "key validation" of its technology and backed its belief that projects specifying Invinity technology "represent clear alignment with the UK's Industrial Strategy by supporting domestic supply chains, enhancing energy security, and growing a UK-manufacturing base for LDES".
