A decade down the road towards a zero emission bus fleet

This month marks a big anniversary in the bus world – it's a decade since the first modern day electric buses took to the streets of London, providing zero emission public transport at the tailpipe.

In December 2013, two zero emission buses operated on routes 507 and 521 – short but busy central London commuter services linking Victoria, Waterloo and London Bridge stations. I was part of the team at Go-Ahead London that planned, developed and operated them on behalf of Transport for London.

It was a significant moment for the industry. We'd already made strides towards cleaner buses by introducing hybrid vehicles and by adopting steadily more stringent diesel emission standards. But it was the first time we'd tested pure electric buses on London's streets, charging them overnight to give them sufficient energy to run all day.

In for a penny, in for a pound – two years later, we decided to retool an entire garage, by switching our Waterloo depot from diesel to 100% electricity – the first depot to go all-electric in Britain, prompting a number of environmental awards.

Since then, it's remarkable how much progress has been made in 10 years. At Go-Ahead, we've gone from just 2 zero emission buses to a fleet of 670 nationwide.

One in ten of Go-Ahead's buses across the UK is zero emission, and that number is growing every month. We're taking delivery of 104 zero emission buses in Oxford in the first quarter of 2024, and we've placed orders with manufacturers for another hundred in London.

While London has set the pace, the Department for Transport's ZEBRA funding scheme has helped operators in other UK cities to invest in clean buses. Adoption is so rapid that a real challenge going forward is whether compliant manufacturers from across the globe can keep pace with demand.

The technology itself has improved markedly. Those first two London buses had batteries above the wheel arch , which separated the driver from passengers. It's now standard practice on single deckers to put the battery on the roof – which itself improved energy efficiency by around 30%, and on new models, batteries are being built into chassis frames. Batteries now have the capability to provide full climate control throughout a double decker bus, where it's requested, as well as simply to move the vehicle forward.

Go-Ahead has set up a Zero Emission Centre of Excellence to share learning between our bus companies around the UK. And it's true that we've encountered plenty of obstacles along the way – including difficulty in getting sufficient high voltage energy supply into our bus depots, with the cost and practicality of connection varying wildly according to grid constraints.

As we move forward, we're trying new ideas. Alongside a partnership comprising SSE, Leeds University, UK Power Networks, Transport for London and BYD, we put together the world's first Bus to Grid proof of concept, which showed that large bus batteries could, in appropriate circumstances, push power back into the grid.

In Bexleyheath, London, we've installed an inverted pantograph that allows buses to get a short 'top up' of electricity to keep them out on the road for longer. And with space in town centre bus depots at a premium, we are looking at different charging infrastructure – including overhead charging and chargers that pop into the ground to compliment current designs.

As to energy sources, the future will predominantly be electric for buses, albeit with pockets of vehicles using hydrogen powered fuel cell technology to constantly replenish batteries for long-distance and highly intensive routes. We are testing hydrogen at Go-Ahead's Metrobus operation around Gatwick Airport, where buses run around the clock and often cover 300 miles a day.

There is a long way to go, and there will be many technological, manufacturing and financial puzzles to solve in decarbonising all 35,000 public buses in Britain. What is encouraging, overall, is that having started down the road, momentum is gathering and we're picking up pace.

We're hosting a 10th birthday party for our electric buses this week at a Go-Ahead London depot in Camberwell, at which local schoolchildren have drawn pictures of what they think the 'green bus of the future' might look like. Zero emission buses are a unifying idea, and it is gratifying to see the degree to which they've caught the public's imagination.

It's been an exciting decade but there is far more to do – working together as an industry, with public sector partners, we can move forward collectively towards a net zero future.