Fire chiefs have voiced concerns over the threat presented by the growing number of large-scale eco batteries being installed across Norfolk to store electricity from wind and solar farms.
The lithium-ion devices - which are an important part of the renewable energy revolution - can be extremely difficult to extinguish if they catch fire.
Several of the items, which can be the size of shipping containers, are being installed over several acres of land at locations across the county to store energy from offshore wind turbines and rural solar farms.
Norfolk Fire and Rescue Service has said it now considers the devices an "emerging risk" on its community risk management plan - the document it uses to assess dangers facing the county.
It is working with the National Fire Chiefs Council to establish procedures for dealing with any blazes, and liaising with local authority planning departments about ways to mitigate the threat.
At a recent meeting, Ceri Sumner, the chief fire officer, said the issue was "keeping her awake at night".
The batteries are also used in smaller sizes in electric cars and in homes, but it is the industrial-scale ones which are causing the most concern.
Ms Sumner said: "In relation to lithium-ion battery storage, this is an emerging area at the moment.
"There is still data and information coming out, both in terms of the risks associated with these types of batteries and the best approaches for dealing with them, should something go wrong.
"They don't go wrong very often, but when they do... they can be quite problematic."
Experts say the risk of fires is low, but when the batteries fail or overheat, they release flammable toxic gases that can spark fast-spreading fires that are extremely difficult to extinguish.
Large-scale installations in Norfolk tend to be in rural areas, away from housing.
Earlier this year, the safety implications were raised when South Norfolk councillors approved plans for a battery facility on a 35-acre site at Swardeston.
The site will be connected to the Hornsea Three North Sea offshore wind farm run by energy company Ørsted.
Swardeston Parish Council said it had "grave concerns" about the use of lithium-ion batteries at the site. But a representative from Ørsted told the planning meeting: "It is not in anyone’s interest, least of all the applicants, for there to be an incident at this site."
READ MORE: Surge in e-bike and e-scooter battery fires prompts warning to consumers
At a recent meeting of Norfolk County Council's scrutiny committee, where the wider issue was discussed, Conservative councillor Mark Kiddle-Morris highlighted two other major battery projects in the pipeline for the region: a 200-acre solar farm near Great Dunham, which would have battery storage, and Green Park, near Necton, which will store power from the Vattenfall and Boreas wind farms, off the coast.
Ms Sumner said the fire service was aware of both schemes and had been involved in the planning processes.
She said the service was also having to consider how people might use the batteries in their own homes. Some properties use them to store energy generated by solar panels.
"It's absolutely an active area that we will be keeping a very close watch on and proactively developing our approach towards," she added.
But Jamie Osborn, Green county councillor, said: "When you look at the threats of causing extreme weather due to climate change, that is a much bigger threat than solar farms or lithium batteries."
READ MORE: Wind farm battery in Swardeston south Norfolk approved
CAR RISK
Conservative county councillor Brian Long welcomed the inclusion of lithium-ion batteries as an "emerging risk".
He cited an incident on TV show Top Gear which showed how long electric vehices can burn for.
Mr Long said: "I'm pleased to see the potential threat from them and how they burn is being taken into consideration.
"We've all seen the videos of the guys on Top Gear when they crashed a rather expensive electric vehicle and how long that burned for.
"Obviously, a battery storage unit is many, many more times batteries than the average family car, so I wondered what extra provision is being considered for those types of facilities?"
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