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This is an article from the December Bulletin Issue written by Richard Dunbar, Park Lodge International.
Electric Vehicle Charging and Battery Electric Storage Systems (BESS) – how do they fit in the risk assessment regime on a fuel station forecourt?
Battery technology has been around for a long time, but today the lithium-ion battery has taken the technology to new heights of power and duration. However, it does have some drawbacks. We have had these batteries in our phones, laptops, tablets, power tools, televisions etc., for years and now they are driving a new revolution in transport from scooters, bikes and cars through to large goods vehicles and public conveyance vehicles. We are even seeing electric fire engines although the diesel back-up generator often makes an appearance somewhere on the truck. They are also used as storage with solar and wind farms, to provide power during power cuts or to supplement the power grid on charging points when demand outstrips capacity.
We have of course lived with the fossil fuel powered motor vehicles for even longer, in fact as early as 1862 there was a Petroleum Act to ensure the safe keeping of petroleum and its products. Today the fuel station forecourt is probably one of the safest and most regulated areas of the United Kingdom public places and usually only the human interaction with the system produces the risk.
Of course, change happens and many fuel stations are offering electric vehicle charging as a service to its customers and if power supplies are adequate and space available without the need of a battery electric storage system (BESS). For some, including 50 motorway service stations, the National Grid and fuel station forecourts the BESS is the only way of providing power storage.
Existing legislation can be adequate but only if the person assessing the risk in the planning and implementation understands the ‘battery’, whether in a vehicle or a BESS. Do not think for one minute that the spurious facts about electric vehicle fires being rare, while refuelling any electric vehicle or plug in hybrids are far more likely to have a thermal event than fossil fuelled vehicles.
Background:
The lithium-ion battery is a simple battery with no chemical reaction other than the electrons moving from one side to the other on charging and back again on discharge, it is referred to as the ‘rocking chair battery’.
If lithium-ion batteries are abused by overheating, penetration or over charging then there can be serious consequences. The Research Institute of Sweden produced a paper on blunt trauma (collisions) where the battery had, what is described as, ‘thermal runaway’. This event is where the heat in the traction battery rises quickly, and around 10C per minute is a serious problem. It cannot burn until the battery vents and then a toxic mixture of products is released into the atmosphere. According to research the batteries start to become unstable at between 60 and 90C.
These products include Hydrogen (30-50%), Carbon Monoxide, Carbon Dioxide, Hydrogen Fluoride, Hydrogen Cyanide, Hydrogen Chloride, small droplets of organic solvents, ethane, methane, hydrocarbons, sulphur dioxide, Nitrogen Oxide, Sulphur Dioxide, Nitrogen Dioxide and some others that are subject to commercial privacy. Mentioned here is hydrogen fluoride, this is toxic and a 1KWh battery can produce between 500 and 6,000 litres of toxic vapour – a typical car 90Kwh 6000L x 90 = 540,000L of toxic vapour is possible, BESS systems have the same issue.have the same issue.
There can be explosions, and the flames are jet like and extremely hot. A hydrocarbon powered vehicle will often burn with a maximum temperature of 750C, but an electric vehicle can reach 2,200C. These flames, acting like a blowlamp, will spread the fire and are powerful enough to do structural damage to buildings (destroy concrete).
Lithium-ion batteries are impossible to extinguish and fire departments have basically three tactics:
So, you can see the risk assessment is important, and the legislation currently surrounding charging, BESS and vehicles is mixed and hopefully one day the Government might, like petroleum, set standards backed up by enforcement.
Legislation with comments:
There will be various aspects of legislation that will apply to the siting of a BESS unit, the main ones being:
Electricity at Work Regulations
ARC risks present and cannot be underestimated.
Detection, explosion relief and suppression:
Detection of an incident within the BESS is imperative, this should include:
Points to remember
‘Recent history tells us that EVs can and do have problems, the trick is to plan and implement the very best protection and response systems to mitigate the effects of an incident should it occur’.