The topic of fires on electric buses has been making headlines recently both within the industry and in the wider media. However, the risk of fires within charging infrastructure is now also starting to be considered.
The number of battery-electric vehicles in operation in the UK is rapidly expanding. According to Zemo Partnership, by November 2023, more than 4,500 hybrid and 2,700 fully battery-electric buses were in operation in this country, while zero-emission registrations accounted for more than 60% of the total for new buses in 2023. A further 955 zero-emission buses are on their way via the second round of Zero Emission Bus Regional Areas funding, the allocations for which were announced last month.
As a relatively new technology is quickly rolled out, the risk at depots is something of an unknown — even though experts say it is low.
Elite Vehicle Supplies has worked with Nottingham City Transport (NCT) to produce what it says is pioneering technology to protect charging infrastructure at bus depots. Elite has installed its system on 15 chargers and one low-voltage (LV) panel at NCT’s Trent Bridge depot, and the business believes it is the first example of such in Europe to have this protection.
Elite, which is already a leading supplier of automatic fire-suppression systems for coaches and buses, is now talking to other local authorities and operators, including Transport for London and Transport for Greater Manchester, about similar installations.
Two years of development of the system began with an approach from NCT. Sean O’Sullivan, Head of Engineering at NCT, says: “The introduction of electric buses at Nottingham City Transport marks the start of an exciting era as we support Nottingham’s aspirations to be carbon-neutral by 2028.
“NCT takes its safety responsibilities very seriously and, throughout our electric bus project, we have worked closely with our partners and suppliers to minimise risk, particularly fire.
“With our Yutong buses using lithium iron phosphate batteries, which are less susceptible to thermal runaway events, along with them being fitted with the Yutong Electric Safety System and having fire suppression systems on board, we wanted the same level of protection at our Trent Bridge garage for the charging infrastructure.
“After discussions at the Northern Regional Engineering Committee, NCT is proud to have worked with Elite Vehicle Supplies to develop and install a fire-suppression system in all 15 of its charging units and the LV unit.
“NCT is the first bus operator in Europe to install this groundbreaking system in its garage charging infrastructure, which has been welcomed by our insurers, who asked us to look at ways of mitigating risks on-site.”
With a significant amount of charging of vehicles taking place overnight in unattended depots, the need for a protection against damage to expensive equipment and negative impact on operations is becoming apparent in the industry.
Elite says the system is unique in that it can suppress a thermal incident without damaging any electrical equipment. It has add-on options such as an alarm-sounder, power cut-off to individual chargers and remote alerts.
NCT is the first bus operator in Europe to install this groundbreaking system in its garage charging infrastructure
The Teesside-based business, which says it protects the majority of electric and hybrid vehicles in the UK, also offers a driver fatigue system, but feedback from operators led to this new venture.
“We’ve basically listened to their needs and designed something around the requirements,” says Scott Forman, Elite Managing Director, who has 15 years’ experience in the industry. “It started with the likes of EO Charging and Zenobe coming to us, saying, because they know we protect vehicles, ‘What would you do in depots?’
“The operators are all concerned about fires in the chargers and in the depots. So there’s a huge piece that’s happening across the country where risk assessments are being conducted by all the major bus groups and all the insurance companies. What the market is looking for is a suppression system designed specifically to protect depots, so that, if there is a fire, it doesn’t escalate and take down a depot with all the vehicles in it or even escalate to neighbouring housing estates or buildings.”
The system uses pressurised tubing using simple pneumatics with minimal moving parts rather than complicated electronics. It uses use Novec 1230 as a “clean, nonconductive” suppressing agent.
Sean says: “In conjunction with NCT, we have got something that the market’s never seen before. It’s a fire-suppression system that is protecting the chargers, protecting the infrastructure. It’s a really unique system. And if there was a fire, the system doesn’t just go off. It shuts down the chargers and sounds an alarm.”
The risk of a fire on charging infrastructure remains low but overloading, old wiring and poor maintenance are among around a dozen potential causes.
It’s a fire-suppression system that is protecting the chargers, protecting the infrastructure. It’s a really unique system. And if there was a fire, the system doesn’t just go off. It shuts down the chargers and sounds an alarm
“The chances of a fire in a charger are quite low,” says Sean. “But, over time, with things wearing and obviously regular maintenance, that may tamper with things in the chargers. And, obviously, there are electrical outlets and things like that. So, we think because everything’s new, nothing’s happened yet. But over time, we think there might be some cases where there might be events.”
Sean adds: “The problem is, it’s such new tech, and that’s why there’s so many concerns. And the insurance companies are really coming down hard on the operators to say you need to get something in place here.”
Although the cost of zero-emission buses and infrastructure presents challenges, particularly for smaller operators, Sean believes the system is a worthwhile investment.
Elite says it has been told by smaller operators that the system would cut down on their insurance premiums.
Sean says: “I think, for a couple of thousand pounds a system, it does make sense for them to have it because they only need to lose a few vehicles and it’s can be a million pound. I think that the premiums coming down will pay for the equipment.”
