A wind farm developer is hoping to build a massive battery plant south of Norwich to ensure there is enough energy when the wind stops blowing.

But the plans, at the three-hectare site between Swardeston and the A47, have sparked concerns about fire safety from experts and local councils.

Hundreds of lithium-ion batteries will be placed in containers around two buildings up to 15 metres high. It will mean that energy generated by Ørsted’s new offshore wind farm, called Hornsea Three, can be stored and then fed into the National Grid on calmer days when the turbines aren’t turning enough.

Ørsted was given the go-ahead last year to build the 230 turbines 120km off the Norfolk coast. The Danish company said the wind farm would produce enough electricity to meet the daily needs of two million homes.

Cables on the seafloor will carry the power to the coast at Weybourne. There it will be transmitted via a huge cable trench, around 35-miles long to Swardeston and connect to the National Grid.

The arrival of huge wind farms off the coast has led to opposition about the amount of infrastructure which needs to be built onshore. Each wind farm has to connect to the National Grid by digging massive cable trenches through the countryside and building new substations.

However, a new front of opposition is now opening with Ørsted’s plans to build battery storage facilities, called Energy Balancing Infrastructure (EBI).

An Ørsted spokesman said battery storage was a “key component of a smarter, more flexible energy system”.

Documents lodged with South Norfolk Council by the power company state the EBI uses “proven technology that does not present elevated risk of accidents”.

But there has been a spate of fires at battery storage plants around the world, including at a much smaller Ørsted-operated site in Liverpool last September. Residents had to close their windows because of the smoke and it took several hours to put out.

The Korean Times reported there were fires at more than 20 battery storage facilities from 2017 to 2019 in South Korea.

At a plant in Arizona in 2019 the failure of one battery caused a large fire which spread across the site. Then in August this year there was a fire at a Tesla battery plant in Australia.

The following month, the world’s biggest battery facility in California was temporarily shut down because of overheating.

Chairman of Swardeston Parish Council Derek Barber wrote: “Ørsted's report implies that their proposed energy storage system is perfectly safe and will have no adverse effects on the environment or the surrounding populace. This is simply not true.

“Much work needs to be done to establish a safe approach to implementing this technology.”

He said it should not go ahead without "further in-depth investigation and strenuous regulation".

A report by Professor Allison Wade, a physicist at the University of Oxford, was also included in objections on South Norfolk Council’s website.

He wrote: “The health and safety authorities do not yet seem aware of the dangers (of these plants).”

He said battery storage plants should be built away from population centres, but Ørsted’s facility is just two miles south of the city and close to homes in Swardeston.

“Until batteries are made safer you have a big, big problem,” Professor Wade added.

He also called for the plants to be regulated by the Health and Safety Executive (HSE). The HSE did not respond to requests for comment.

However, an Ørsted spokesman said “careful consideration” would be given to the design, operation and maintenance of the project.

They added: “We will work closely with our chosen suppliers to develop robust safety plans in consultation with the local planning authority, as well as actively engage with the local fire and rescue service as the project progresses.”

Why now?

The Planning Inspectorate granted Ørsted permission in December last year for the wind farm and onshore infrastructure, but there was no mention in that application of the battery storage plant, something which has angered the parish councils.

Instead, Ørsted is applying separately to South Norfolk Council for permission for it.

The company said the plant would fit into the site which it had already been given permission for by the Planning Inspectorate.

Asked why the plant was not included in the original application they said: “Since receiving development consent for Hornsea Three, the optimisation of our designs has presented an additional opportunity to site the Energy Balancing Infrastructure (EBI) without the need to use any additional land.”

An application is expected next year.