‘Is battery-electric retrofit part of zero-emission bus transition?’

Zero emission bus retrofit

The race to zero-emission is occurring nowhere faster than in the UK bus world currently. We have over 750 battery-electric buses in service and we expect over 50 hydrogen fuel cell-electric models to be in operation by the end of the year.

By the start of 2022 we could have close to 1,000 zero-emission buses (ZEBs) in service. The All-Electric Bus Town scheme in Coventry should provide us with 300 more by 2025, and the Department for Transport’s Zero Emission Bus Regional Areas plan will support an estimated 300-400 ZEBs. Scotland, Northern Ireland and Wales are each ramping up their support programmes ahead of COP26 in November.

Zero-emission bus retrofit could form part of transition

All of this is good news. But for an industry that is struggling to return to pre-pandemic levels of passengers, commercial operators are not rushing to buy new buses just yet. For industry to be able to support the rollout of 4,000 ZEBs in England by 2025, the government must send out the message that buses are safe to use, including support for the #BackOnBoard campaign.

Another avenue that many operators are keen to explore is retrofitting older diesel buses to zero-emission. Removing diesel engines from buses that are six to 10 years old and retrofitting a battery-electric or hydrogen fuel cell-electric powertrain is an attractive option for several reasons.

Many benefits of such an approach…

Firstly, it is more cost effective than buying a new bus, so operators could achieve a fully zero-emission fleet sooner. Secondly, it removes older diesel buses rather than seeing them cascaded, which tends to move more polluting vehicles from one place to another. That could mean that less profitable services, which may have the oldest fleets, could see some ZEBs in operation, range and infrastructure permitting.

Other benefits of retrofit include higher utilisation of charging or refuelling infrastructure, improving the cost effectiveness of future proofing depots. There is also a good case for supporting UK PLC through design and fitment jobs, as well as supporting components from a more local supply chain. A crucial benefit will, of course, be the greenhouse gas savings that ZEBs will bring, through either battery-electric or fuel cells using green hydrogen.

…but also several challenges, too

With this potential, however, comes limited experience. So far only a handful of buses have been converted to zero-emission, with varying degrees of success. The major challenge is that you still have an older bus designed originally to support a diesel engine. Ageing components that have nothing to do with the new powertrain can cause problems and limit vehicle availability.

Importantly, these early lessons are being fed into the next generation of retrofit system designs, with future retrofits likely to include significant refurbishment to improve vehicle availability. A refurbishment also has the potential to extend the life of the vehicle to improve the overall total cost of ownership.

The next few years are going to see the greatest investment from governments in new buses in my 32 years. To make sure the bus industry has all the options available, Zemo Partnership’s Bus Working Group will be exploring the potential of zero-emission retrofit and what its role will be in supporting the race to zero.