Megabatteries: low tech, high risk
Alongside the proliferation of ever-larger solar farms comes the network of megabatteries, designed to ‘smooth out’ the supply from an inherently intermittent energy source such as sunshine and wind.
Large compounds of shipping containers, each holding hundreds of thousands of lithium-ion battery cells, are being placed alongside solar farms, but also as stand-alone units close to National Grid connection points (‘nodes’). Like the solar farms, they are now a thriving market-driven investment bubble, looking for big returns before the music stops.
Oxford Professors Peter Edwards and Peter Dobson, writing in Fire Technology in November 2024, said: ‘There are growing and entirely reasonable public concerns about the widespread installation of large grid-scale Battery Energy Storage Systems (BESS) based on lithium-ion batteries in both urban and rural areas in the UK with little knowledge applied about the explosion, fire and pollution risks associated with them.’
Some key facts about li-ion batteries
- Rapid Growth of Battery Storage Projects
Lithium-ion Battery Energy Storage Systems (BESS) are hailed as a major contributor to the UK’s clean-energy strategy. In 2024 the operational capacity rose to over 7GW, while projects in the ‘pipeline’ totalled around 85GW, a 70% increase in a year.
- Fire Risks from Thermal Runaway
The principal risk from BESS is ‘thermal runaway’, where chemical reactions within a li-ion cell lead to a chain effect within a whole container. According to the Fire Technology report ‘Lithium-ion batteries by their very nature are intrinsically fire-prone and are notoriously difficult to distinguish. In terms of their large-scale in BESS, the more lithium, the larger the fire and explosion risks’.
- Explosive Chemical Composition
The batteries contain a chemical oxidiser and a fuel in a sealed container. According to Profs Edward and Dobson ‘this situation… is rarely found in normal, everyday circumstances – the most obvious exceptions are explosives and rocket propellants’.
- Challenges in Extinguishing Battery Fires
Extinguishing a Lithium-ion fire requires starving it of oxygen, which is hard to do: so current advice is to let it burn out while cooling nearby units to prevent them joining in. This leads to very substantial water-runoff which may be contaminated.
- Explosion & Contamination Hazards
The chemistry of Li-ion batteries in a fire offers a high potential for vapour cloud explosion, which may greatly increase the risk to surrounding areas. Though all BESS are fitted with fire suppression systems, there is currently no definitive national guidance on notification of fires to emergency services or on how fire services should deal with them. The usual procedure is to evacuate residents, keep the area cooled with water and let the fire burn itself out.
- Real-World Incidents in the UK
Although Lithium-ion battery technology is constantly evolving, thermal runaway has been noted in every country using BESS. The EPRI BESS Failure Incident database records two incidents in England in 2025. In February, a fire in one unit of a BESS under construction half a mile outside Tilbury took 24 hours to extinguish; and in March two containers were affected by a 7-hour fire at a solar farm near Cirencester, a quarter of a mile from the village of Preston and less than a mile from the town.
Though BESS installations are much smaller than solar farms, they pose a substantial risk to nearby communities. We oppose them on that basis, wherever they are proposed, because they are a direct result of the wrong technologies being used for the wrong purpose in the wrong places.