The Hazards of Battery Energy Storage Systems Supporting Renewable Energy Sources

There is general agreement that to reduce the rate of global warming the world must as quickly as possible move away from being dependent on hydro-carbon produced energy. The alternatives also have disadvantages but they need to be developed and brought on stream as quickly as possible. Atomic power and tidal energy involve massive projects requiring massive funds and take many years longer than the parliamentary election cycle to complete. Hydrogen and other new technologies are at an early stage of development and lack any infrastructure for their distribution. So what is currently available?

Solar and wind power are currently the two front runners. Wind turbines are an old technology that has been modernised but photo-voltaic solar power is a rapidly developing new technology dependant on access to large quantities of silver which is already in short supply.

Their biggest disadvantage is that both sources of energy are intermittent. Solar obviously does not work at night and is less efficient during cloudy conditions and far less efficient when the sun is low in the sky. New solar panels are about 22% efficient at converting solar energy into electricity but over a typical 12 month period in the UK this drops to about 11%. Also, during the recent high summer temperatures of around 29°C, efficiency dropped by around 22% as the panels overheated. During these two hot days, total solar generation in the UK dropped by 24%. Another major disadvantage of solar energy is in winter when the sun is low in the sky, energy generation drops dramatically at a time when it is needed the most. Wind turbines are a lot more efficient and over a 5 year period wind turbines are on average 40% efficient at converting wind into electricity. Under favourable conditions they can reach a maximum of almost 60%, before they have to be shut down due to dangerously high wind speeds.

In the short term, atomic energy and hydro-carbon based energy will be essential until a more robust energy supply system can be developed. Achieving this is highly dependent on a significant investment in the National Grid system to meet the country’s current and future needs. One approach favoured by the international finance houses funding such schemes is to build large Battery Electricity Storage Systems, BESS. These are not your old lead/acid batteries but a relatively new technology based around lithium-ion compounds. This technology is dependent on access to large quantities of lithium, nickel, manganese and cobalt, the latter having serious environmental and health issues associated with its mining. China dominates the production of Lithium-ion batteries and in 2021 produced some 79 percent of all lithium-ion batteries manufactured. The idea is to store electrical energy from solar and wind installations for release back into the National Grid system when wind turbines and solar panels are not generating. They can also be used to download electricity from the National Grid when electricity is cheap and sell it back to the Grid when prices are high. The BESS proposed for the Grays Lane Site is rated at 40MWh which if fully charged can supply 40 Mega Watts for ONLY I HOUR

 Most of us have never seen a BESS but there is one being constructed at the far end of the Halesworth Business Centre, just off the Norwich Road on the way out of Halesworth to Bungay. An aerial view of this site shows the sort of large industrial complex that will make up part of the solar factory proposed for the Grays Lane site. These are large 40 foot containers which together with the inverters and control installations will ruin this quiet section of Suffolk countryside. Link to photos.

These containers house thousands of individual lithium-ion cells, miles of cabling and millions of connections, any one of which could fail. Unfortunately, all types of Lithium-ion batteries have a known weakness of thermal overload which when it occurs leads to a catastrophic “loss of control” of the battery. When a loss of control occurs, the BESS goes into what is termed a “thermal-runaway” which poses a very serious hazard to people, animals and the environment. There have been more than a few “loss of control” incidents around the world which have resulted in “thermal- runaways” which have all been very serious, resulting in explosions, wide scale toxic pollution and in some instances deaths.

What happens during a thermal-runaway? When a battery fails, the battery cell temperature rises incredibly fast (milliseconds). The energy stored in that battery is suddenly released. This chain reaction creates extremely high temperatures around 752°F / 400°C. A lithium-ion conflagration does not require oxygen because it is a thermo-chemical reaction against which normal fire suppression measures are ineffective. The only way to control it is by using vast quantities of water to bring the temperature down so that the reaction ceases. Alternatively, it can be left it burn itself out.

The massive quantities of water to cool just one container undergoing a thermal-runaway will result in the serious pollution of the neighbouring environment, ditches and waterways. However, if left to burn out the highly toxic gases produced will be spread over a very wide area. A thermal-runaway is not common but when one occurs, it is a very dangerous toxic situation, especially for the Firemen attending the inferno. Fire Officers have to decide whether to attempt to bring the thermal-runaway under control or let it burn out and not expose their firemen to serious risks.

A thermal-runaway in Liverpool, in just one container, took 58 hours to bring completely under control by using vast amounts of water.

Germany has banned electric vehicles from underground car parks following a major incident that “took out” a multi-story building. Transport for London has banned all

e-scooters from its transport network as have many rail companies, including Greater Anglia. Also, Road Transport Regulations define lithium-ion batteries as “Dangerous Goods” which are prohibited from being transported by air except for small electronic devices such as mobile phones and laptops. Drivers transporting larger lithium-ion batteries have to undergo specific training before being permitted to transport these “Dangerous Devices”

In summary, a thermal-runaway is largely uncontrollable and is often left to burn itself out. As a consequence, highly toxic gases are produced, principally hydrogen fluoride but also hydrogen cyanide and phosphoryl fluoride. Hydrogen fluoride is very toxic and can be lethal by inhalation, ingestion and skin contact. Explosions are caused by the build up of highly flammable gases, hydrogen, methane, ethylene and carbon monoxide and large flames up to 50 feet high are fed by flammable liquids coming from the cabinets. The hydrogen fluoride gas reacts with water and the moisture in the air to form hydrofluoric acid which pollutes the environment. Hydrofluoric acid is very nasty stuff being capable of dissolving concrete.

Due to the risk of a loss of control with a BESS, many developers are deliberately not publicising the capacity of their BESS making it impossible to assess its hazard level. They are using alternative names such as “Energy Balancing Infrastructure” to avoid the negative image of lithium-ion battery electricity storage systems which is developing as the dangerous hazards of a BESS become more widely understood.

Currently, the solar factory sites are unmanned and are monitored from afar, often by organisations in other countries. The Liverpool BESS site was monitored by a company based in Denmark which relied on electronic communication with sensors on the site. This organisation raised the alarm about half an hour after a local resident had raised it with the Liverpool Fire and Rescue Services. The resident had been alerted by the sounds of the explosion.  It is proposed that the solar factory, either side of Grays Lane, will be monitored by a company in The Netherlands. How quickly will the Dutch monitors react and how quickly will the volunteer firemen manning the Halesworth Fire Station be able to get to Grays Lane if there is a “loss of control”? It takes a thermal-runaway up to about 11minutes to become an inferno.

The Lithium-ion battery technology is new and developing rapidly and in time it may well be safe but currently the risk of a catastrophic failure is always present. Unfortunately, legislation is lagging far behind this technology and as a result its development is largely uncontrolled. The countries Fire and Rescue Services are not statutory Consultees in the planning process and they are still developing a procedure as how to tackle a thermal runaway.

This risk and the consequences of a thermal runaway are known by those scientists active in the field. However, solar factory developers studiously avoid discussing this topic because large scale ground mounted PV-solar and BESS installations continue to make eye-watering profits for investors. The pricing is linked to the cost of wholesale gas and as a consequence the UK General Public are most unlikely to see any reduction in their electricity bills in the foreseeable future.

Currently, Lithium-ion BESS should not be approved by the District Council’s Planning Committees until the serious hazards of a loss of control and the resulting thermal-runaway have been removed. The risks to residents, Fire-fighters and the environment are just too great and in the case of the environment will be very damaging and long lasting. How will a District Councillor on a Planning Committee or a Planning Officer be able to justify a decision to approve a planning application which includes a BESS when the dangers of a thermal-runaway are so well known?

The Deputy Fire Safety Commissioner of the London Fire Brigade, Charlie Pugsley spoke at the Energy Storage Summit 2021 at which reports on fire safety issues at BESS were discussed. He commented that the London Fire Brigade had spent the past few years “reflecting on what was foreseeable” since the tragic Grenfell Tower fire at a high-rise housing unit in 2017, which was exacerbated by the building’s flammable cladding. He said:

“If we know some things could fail catastrophically or it could have those effects,” he said, “it’s going to be a difficult day if one of us is standing there in court saying we knew about it but we didn’t do anything.”