Subscribe to Our Newsletter

Contact us:

Cleve Hill – Batteries Included?

By Richard Fleury

Of all the reasons to object to a solar power station at Graveney, the giant battery at its heart is by far the most worrying.


The Battery Energy Storage System or BESS is both the key to storing renewable energy and its dirty secret.


And while the company promoting the Cleve Hill power plant happily exploits the public's positive perception of solar power, concern is growing among public and experts alike about the risks of current BESS technology.


Scientist Dr Bruno Erasin, a biochemical engineer who lives near the site, warns of safety risks from fire and leaking toxic chemicals. His report to the Planning Inspectorate concludes that a battery fire would pose “a foreseeable and significant risk to human health”.


Some doubters accused him of scaremongering, 'showboating', of exaggerating the risks and general NIMBYism. Are they right? Or will those solar panels really conceal an environmental timebomb threatening runaway fires belching clouds of lethal gas?


Either way, here in Faversham we will be the world's guinea pigs for this technology. A battery of this size has never been built before, let alone between three population centres and more than 100,000 people.


Completely untested on this scale, a 350 MWh battery will be almost three times the size of the current record-holder. In 2017 Tesla made global headlines when it built the world's biggest battery at Hornsdale in remote South Australia.


The Graveney battery site will cover more than eight hectares, an area bigger than Faversham's Recreation Ground.


Vast as it will be, it won't hold the record for long. It will soon be dwarfed by BESS installations being planned around the world. Battery storage is the big new thing in energy and will transform the industry in coming years. By 2023, analysts estimate the battery storage market will be worth more than $13 billion.


As we rely more on greener but less predictable solar and wind energy, battery storage helps maintain a steady supply of electricity to the national grid. And as well as stabilising supply, large-scale installations allow energy companies to make huge profits from energy trading.

“Energy is just a financial commodity. It's bought and sold constantly. And what they try and do is generate it and sell it at the time when it has got the highest price. It's like an instant oil trading situation,” says Professor Sir David Melville of the Faversham Society which is strongly opposed to the Graveney power station proposals.


Tesla's Australian megabattery made £0.5 million in one two-day period in 2018 and £16.5 million over the whole year for French renewable energy company Neoen.


The proposed Graveney monster battery will import electricity from the grid too, making millions annually by buying power when it's cheapest and selling it back when demand – and prices – peak.

“And, of course, there is also buying and selling across the channel,” says Sir David Melville. “We have got two major links: one to Belgium and one to France.”

Developers CHSP Ltd say the battery might remain as a storage facility for the wind farm after the proposed solar plant is decommissioned in 30 or 40 years' time. “It sounds like they think it has an even longer term future,” says Sir David.


Energy corporations are, of course, entitled to benefit from the storage goldrush and if a megabattery is what it takes to make a solar power station sufficiently profitable, then some will argue that's a price worth paying.


In Graveney's case, the price tag will also include the loss of an important wildlife habitat, a much-loved leisure amenity and an unexplored archaeological treasure trove. But to some, such as Swale Friends of the Earth who have come out in favour of the Cleve Hill scheme, it's worth paying to help avert an impending global climate crisis.




Proposed new battery array (yellow) , substation (blue) and surrounding bund (green). The areas of solar panels are labelled rather handily alphabetically A to Z.

Existing substation at Cleve Hill, connected to the National Grid.


At present, BESS installations are usually, although not always, arrays of lithium ion (li-ion) batteries. Li-ion is likely to remain the leading battery chemistry until superseded by next-generation technologies such as solid state and Lithium-Sulfur.


Why? It is by far the cheapest. Prices have plummeted 85% since 2010, with li-ion batteries pouring out of new factories in China, the US and Thailand, built to feed growing demand from the electric car market.


But li-ion batteries have a downside: They spontaneously catch fire. For an analysis of the science, see here.


“Fire is a major risk,” says the AIG Energy Industry Group's report Lithium Ion Battery Storage Systems: The risks and how to manage them, “With a number of li-ion battery-related incidents hitting the headlines in recent years, from exploding Samsung smartphones to electric car fires and even a Dreamliner catching fire at Heathrow, along with a Hawaiian BESS facility fire.”


Li-ion batteries are prone to what’s called 'thermal runaway' which is, if anything, even worse than it sounds. A self-destructive cycle in which excessive heat keeps creating more heat. It can be caused by battery defects, mechanical failures or over-voltage, leading to gas build-up, rupture of the battery cell, fire and explosion. Thermal runaway can also spread rapidly from one battery cell to the next. In one recent experiment the temperature went from 220º centigrade to 687º “in a few seconds.”


The phenomenon is well-documented. According to a pioneering study of large-scale li-ion battery fires published in the research journal Applied Thermal Engineering as recently as July this year, “Thermal and fire propagation of multiple Lithium Ion batteries can be triggered easily, and will accelerate continuously. In the later stage of the fire, more and more batteries can be ignited simultaneously”.


For a sobering demonstration of the ferocious speed and force of thermal runaway and just how easily and dramatically reignition occurs, google 'robot simian thermal runaway' and watch the NASA video of a li-ion battery fire.


Not only are they notoriously difficult to put out, li-ion fires can flare up again after being extinguished.


“One of the most concerning features of battery fires is that they can seemingly ignite or reignite days or weeks after they were thought to be extinguished,” says another report by global insurance giant AIG.


In October 2017 a li-ion-powered Tesla crashed into a barrier in Austria, the car kept reigniting, forcing firefighters to battle the flames for hours. The car had to be quarantined for 48 hours.


“Now imagine 20,000 Tesla cars parked two deep on Faversham recreation ground with no way of getting to the middle ones in the event of a fire,” says Sir David Melville, physicist and vice chair of the Faversham Society. “(li-ion) fires are happening all the time. It is creating an unnecessary risk.”


There have been no fires in batteries of this size for one simple reason: There have been no batteries of this size before. “There is zero experience of a battery of this scale. It's unprecedented,” says Sir David.


However, several li-ion BESS installations have caught fire:

  • In 2012, a fire caused £2.5 million worth of damage at a new 1.5 MW battery attached to a solar power plant at Flagstaff, Arizona.

  • In 2016 a BESS caught fire while under construction in Franklin, Wisconsin, costing more than £3 million. And the following year a container-sized li on battery exploded at a power station near Brussels run by the country's main electricity producer, Engie Electrabel The first battery at the Drogenbos plant to be tested for storing wind power, the 1MW installation caught fire within a month releasing a cloud of toxic fumes that forced thousands of people to stay indoors.


The 2016 single battery fire at Drogenbos, Belgium

There are many other examples, big and small and these are detailed in the attached science report.


Who will build the proposed Graveney BESS? Not Tesla, as early newspaper reports speculated. Cleve Hill Solar Park Ltd, the company formed by Hive Energy Limited and the German company Wirsol to carry out the project, is working with Swiss firm, Leclanché, which it describes as 'a world leader in the battery industry'.


But Leclanché has never built a battery installation approaching this scale before. Its largest BESS to date is a li-ion storage facility opened in Cremzow near Berlin, Germany, earlier this year, with a capacity of 34 MWh, less than a one-tenth of that proposed for Graveney.


CHSP Ltd describes the li-ion BESS as “tested technology”. Technically, that’s true but all the testing worldwide shows that these batteries are inherently unstable. The risk of spontaneous combustion and fire comes with the technology. And there is nothing the manufacturers can do about it. The global insurance industry is fully aware – AIG calls it “a key emerging risk” – and, given the potential costs of a disastrous fire it is far from clear whether any insurer will touch the Graveney project.


What would happen in the event of a major fire? How would it be managed? At the time of writing, CHSP Ltd had not contacted with Kent Fire and Rescue Service to discuss how it might handle a fire.


Instead, the Faversham Society made its own inquiries and this was the Kent Fire and Rescue Service's response: “In broad terms and prior to a decision relating to any on-site fire suppression systems, KFRS would extinguish a fire on the site by applying large volumes of water. “Alternatively, if no life risk were present, then a controlled burn strategy may be considered and employed in order to try to minimise the possible environmental pollution that may be caused with fire water run-off.”


A 'controlled burn' basically means allowing the fire to burn itself out.


“The whole of the recreation ground on fire for months? The prospect of letting it burn out is horrendous,” says Prof Sir David Melville.


But dousing with water could have far, far worse consequences. Adding water to burning li-ion batteries releases all kinds of toxic chemicals, among them a colourless gas with a powerful, irritating odour: hydrogen fluoride.


Hydrogen fluoride is among the world's most dangerous chemicals. In its liquid form, it is highly potent acid capable of dissolving concrete and steel. It is used to split rocks, etch glass and is favoured by acid attackers. As a gas, small doses can cause fatal poisoning, respiratory problems, lung damage, skin burns. Long term effects of exposure include chronic lung disease, scarring and blindness. It's a horrible way to die. If you're feeling strong of stomach, google “hydrofluoric acid burns”.


How much HF gas could Graveney's li-ion megabattery fire create? What would be the consequences for Graveney, Seasalter, Faversham and anyone else nearby? How long is a piece of string? Unfortunately, what we are dealing with here is the world's longest piece of string.


In the 1986, the US oil giant Amoco ran tests in the Nevada desert to see what would happen if 3,700 kilos of hydrogen fluoride was released. The results were nightmarish. The gas immediately rolled out across the land in a thick, ground-hugging cloud. In minutes, twice the lethal levels were detected two miles downwind. This video is available on the Faversham Eye web site.


As recently as 2017, a research paper published in respected science journal Nature called Toxic fluoride gas emissions from lithium-ion battery fires (Fredrik Larsson, Petra Andersson, Per Blomqvist & Bengt-Erik Mellander) drew some disturbing conclusions.


Describing the risks as 'severe' the report calculated that a small 1,000 KWh battery storage unit on fire would produce between 20 and 200 kilos of HF gas per minute. Scale that up to Graveney's proposed 350 MWh megabattery and the numbers are off the scale terrifying.

The worst-case scenario – a catastrophic fire spreading through the whole battery enclosure – would immediately release between 140,000 kilos and 1,400,000 kilos, or 140-1400 tonnes of the deadly gas. One barely dare imagine the armageddon that might wreak.


In short, a burning li-on megabattery is not just a firebomb, but also a chemical weapon with destructive potential rivalling a nuclear accident. Like nuclear energy, large-scale Li-on battery storage is completely safe...until it's not.


“It's a bit like nuclear power,” says Sir David Melville. “There has always been this sort of runaway risk with nuclear power. We've had Three Mile Island and Fukushima in Japan. It's that potential kind of risk that is low probability but is absolutely catastrophic and it takes off in the same way. You haven't got radiation emissions but you've got potential toxic gas emissions and the volumes of that could be large.”


In his report, Dr Bruno Erasin warned a fire at Graveney site poses “a foreseeable and significant risk to human health” over the solar plant's 40-year operational life and recommended future large scale BESS installations should be at least ten miles away from homes.


As the crow flies, Faversham, a town of around 20,000, is three miles away from the proposed megabattery, Whitstable's 32,000 residents are five miles away and Canterbury, a city of 55,000, is seven miles away.


CHSP Ltd's response? “Locating battery storage at least 15 km from residential properties is not considered to be practicable in the UK.”


Which begs the question: Then why is this part German-owned company proposing to build the world's biggest battery here in densely-populated South East England?


“If you look at all the big solar power stations, in Australia, America, India, Mexico, China, they are in places with a lot more sun and a lot more space,” says Prof Sir David Melville.


“Something of this size is totally inappropriate almost anywhere in the UK.”

We'll come back to this question.


As if there weren't already enough compelling reasons to doubt the wisdom of the Graveney megabattery, here's another: The proposed location is on a flood plain. And guess what? Li-ion batteries catch fire when submerged in water.


As one of CHSP Ltd's own barristers jocularly observed at a recent Inspectors' hearing, “electricity and water don't mix particularly well”. Which, together with low-lying land, rising sea levels and increasingly unpredictable weather, makes the Graveney marshes an unusual first choice.


Cleve Hill's near neighbours are 65 properties on the coastal section of Faversham Road, Seasalter East of The Sportsman pub. This stretch of road is so vulnerable to flooding that Canterbury City Council planners will not permit new homebuilding and residents were evacuated as recently as December 2013 due to a tidal surge. It is designated a 'Wave Overtopping Hazard Zone' because water crashes over the sea wall every decade or so.


Yet, CHSP Ltd consistently plays down the threat. “They say flood risk is very low but they have taken huge precautions to deal with flood risk,” says Prof Sir David Melville. “Clearly they are not confident.”


Those precautions include building a 5.3 metre high bund or concrete wall around the battery enclosure – a serious civil engineering project – and compulsory purchase of the sea wall and foreshore.


“Interestingly, their plans show lots of individual transformers in among the solar panels around the fields,” says Sir David Melville. “But they've got those on floats. The transformers are on floats!”


Even without an accident, the project would see hazardous material regularly transported through Graveney and past the 100 children at the village primary school.


Sir David explains: “Within ten years they will be into constant replacement of thousands of batteries which are potentially toxic if they've failed because they've burst. You're taking toxic materials past a school all the time.”



A vision of a renewable future - or the potential for toxic escaping gas clouds and uncontrollable and runaway firestorms.


There has to be reason why a low-lying, coastal floodplain near a primary school and between three centres of population is so very attractive to an international energy company. And there is.


It is, of course, money. Building new connections to the national grid is hugely expensive but Cleve Hill presents a low-cost, ready-made hook-up.


Since 2013, electricity generated by wind turbines off the coast – the London Array wind farm – has comes ashore here to be fed into the National Grid.


The original plan for the London Array wind farm was for 1,000MW. 630MW in Phase One and a further 370MW in Phase Two. Phase Two was cancelled in 2014, leaving extra available capacity in the substation. CHSP Ltd can set up its monster battery here for a fraction of the cost of connecting a more suitable site to the grid.


“It is an opportunistic location,” says Prof Sir David Melville. “It's plug and play basically.”

Despite the apparent lack of official disaster planning and consultation, we do have some idea of what a moderate fire and gas leak from Graveney would look like. Thanks to software developed and used by the US Environmental Protection Agency, it's possible to model gas dispersion with reasonable accuracy. Dr Erasin calculated the effects of a 10MWh fire emitting hydrogen fluoride fumes for one hour on the surrounding human population. His figures were presented to CHDP Ltd as part of the official planning inquiry. The company did not refute or question them.


Remember that this is very, very far from a worst case scenario. This is what would happen if less than three percent of the battery installation caught fire. Nevertheless, the consequences are chilling.


A hydrogen fluoride gas concentration of 30 ppm is categorised as Immediately Dangerous to Life or Health by the US National Institute for Occupational Safety and Health. Its lethal 10 minutes HF toxicity value is 170 ppm. The elderly and under-fives would be especially vulnerable.


Depending on its direction, a 23mph wind would carry the toxic cloud to Graveney Primary School and its 100 children within a minute. It's unlikely there would be any survivors. The rest of Graveney's 500 villagers would be next.


After nine minutes it could reach Faversham. By now the concentration of hydrogen fluoride would be 44 parts per million. Inhaled for between 30 and 60 minutes at 50 parts per million, the gas is fatal to humans according to NIOSH.


With the wind blowing in another direction, it could reach Whitstable in 15 minutes, or Canterbury in 20 minutes.


The irony is that Cleve Hill is already redundant. The UK is currently on track to meet renewables targets without it, largely thanks to the recent proliferation of small scale, localised solar and battery installations.


Meanwhile, the li-ion goldrush gallops on apace and Wirsol is already planning its next UK megabattery project. It has already applied, with UK-based Tribus Clean Energy, to build what would be the country's largest solar power station with even more battery capacity than Cleve Hill. If approved, the 500 MWh 'Sunnica Energy Farm' will consist of two sites near Worlington in West Suffolk, and Chippenham in East Cambridgeshire and go operational in 2025.


It's our view that there will be a major BESS disaster – it's a matter of when, not if – and if the Graveney scheme goes ahead it's as likely, if not more likely, to happen here as anywhere else.


The li-on BESS is an interim technology, a flawed stopgap until something safer guarantees equivalent profit margins. Energy companies exist to make profits, of course, but not at the expense of public safety.


In America, where BESS technology is more established and more widely understood, people are well aware of the risks. The same is true of the hazards of HF. In July this year a New York Times editorial asked: This Chemical Kills: Why Aren't Regulators Banning It?


All the warnings are there, we only have to read them. Faversham should be remembered for good reasons, not mentioned in the same breath as Chernobyl, Bhopal, Piper Alpha or Aberfan.





Faversham-based Richard Fleury has been a journalist for 30 years, writing for national newspapers and magazines including BBC Top Gear, Arena, GQ, Wired, the Times and Sunday Times and the Guardian.