Are London’s new hydrogen-powered buses the future of green transport?

Are London’s new hydrogen-powered buses the future of green transport?

Last week, Sadiq Khan went to Perivale for the launch of 20 hydrogen-powered double decker buses for London, the first of their kind to enter service in England. The moment had been a long time coming: the Mayor unveiled “the world’s first double-decker hydrogen bus” during an International Zero Emission Bus Conference at City Hall in November 2016 and announced in May 2019 that Transport for London had ordered 20 of them. There have since been setbacks: manufacturers Wrightbus went into administration and then came the Covid crisis. But with the vehicles at last delivered, Khan had two stories to tell about them.

As part of his campaign to show that London is essential to “levelling up” the country, the Mayor was able to highlight how investment in the buses is supporting jobs across the UK. They are produced by the (now rescued)  Wrightbus in Ballymena, the gas cylinders they require are supplied by Luxfer in Nottingham and the hydrogen fuel by Air Liquide’s plant in Runcorn, using waste hydrogen from an industrial plant.

The vehicles, which will be operated by Metroline on route 7 between East Acton and Oxford Circus, are “a great demonstration of how tackling air pollution and the climate crisis and boosting economic growth is about regions working together, investing in the very latest technology,” Khan said.

For metropolitan audiences, the unveiling was accompanied by a more familiar message about green transport: “I’ve worked hard to ensure TfL’s entire core bus fleet across London now meets ULEZ [Ultra Low Emission Zone] standards and this includes 500 electric buses. Our new investment in hydrogen buses will move us even closer to our ambition of making all London buses zero-emission by 2030”.

The hallmark feature of hydrogen buses is that they emit only water through their exhaust pipes. They join a London bus fleet of just over 9,000 which, as well as just over 500 electric battery-powered vehicles also includes nearly 4,000 diesel-electric hybrids (1,000 of which are New Routemasters, introduced by Boris Johnson). TfL announced in January that “the main bus network” or “core fleet” as a whole now meets Euro VI emissions standards or better, making it fully ULEZ-compliant.

Hydrogen-powered buses are not new to the capital: single-deckers plied route RV1 between Covent Garden and Tower Gateway via the South Bank from 2004 until the route was axed in 2019. Of the ten that were then operating, some were redeployed to route 444 until spring 2020. TfL says two of them will soon be operating again, using hydrogen from Perivale.

Mayoral publicity is able to boast that London has “one of the largest fleets in Western Europe” of zero tailpipe emission vehicles, though the capital trails Moscow, which currently has more than 600 electric buses and is due to increase this by more than 1000 by the end of the year. World-leader China has 421,000 electric buses operating in its cities in total, including 16,000 in Shenzhen.

The funding for London’s 20 hydrogen double deckers – which are currently considerably more expensive than other buses – and a state-of-the-art fuelling station for them has come from TfL (£6 million), various European bodies (more than £5 million) and by the UK government’s Office for Zero Emission Vehicles (£1 million).

TfL, which leads a group of UK authorities in the Joint Initiative for Hydrogen Vehicles across Europe project, is calling for central government support to help it achieve a 100 per cent zero exhaust emissions fleet by 2030. Moscow aims to get to the same point by 2032 and Coventry by 2025.

Behind the figures are some lively differences of opinion about TfL’s approach to cleaning up the bus fleet: whether it has moved quickly enough, the comparative strengths of hydrogen and electric battery power, and whether TfL needs to make a choice between the two technologies.

Executive chairman of Wrightbus Jo Bamford, who is also founder and executive chairman of hydrogen producer and distributor Ryze, points to the ability of hydrogen buses to travel further than electric ones without refuelling. He also argues that it makes sense for the UK to embrace hydrogen technology, given that China has cornered the market in the lithium batteries that power electric buses.

He urges Khan to go much further with hydrogen. “London could drive jobs outside London,” he says. “Let’s pick Darlington, Tees Valley or Aberdeen as a centre of expertise.” Aberdeen was the first UK city to launch Wrightbus’s hydrogen double-deckers, Birmingham will get 20 later this year and Bamford has said he hopes to roll out 3,000 across the country by 2024.

Bamford’s enthusiasm for hydrogen is shared by the Conservatives’ London Assembly transport spokesperson Keith Prince. “You get a full day’s work out of it” he says, and argues that “if you think about it, resources to manufacture batteries are finite. There will probably be some kind of shortage”. Metroline Group Engineering Director Ian Foster is another big hydrogen advocate, and Tower Transit’s David Yorke says he “would love to run more of these vehicles”.

But others in the world of green transport question the business case for hydrogen fleets, partly because running hydrogen buses on multiple routes requires a whole new supply chain and distribution network. Businessman and government adviser Michael Liebreich, who was a TfL board member under Mayor Johnson, is a strident critic.

He maintains that more than half the energy used to produce hydrogen is wasted making it a less efficient fuel compared to batteries and argues that the greater travel range of hydrogen vehicles is irrelevant for London, as urban buses don’t need to cover more than 100-150 miles a day. He claims hydrogen has been “used by TfL management as a way of slowing down the shift to electrification. We’ve soft-pedalled”.

Opposition London Assembly Members from different parties say the Mayor has not made fast enough progress on greening the bus fleet overall. Prince says he would “sum up the approach as unambitious,” while Liberal Democrat Caroline Pidgeon has called for “a far more radical vision,” pointing to the speed at which some US school districts are electrifying their fleets.

However, new models of bus have to be paid for and introduced with the agreement of the private companies TfL contracts to operate its routes, usually when those contracts are renewed. And Labour Group transport spokesperson Elly Baker’s concern is that the government’s current approach to funding TfL – which she characterises as “punitive demands for long-term cuts and savings” – will force the Mayor to slow progress towards greening the fleet.




How do they work? A lithium-ion battery (the same kind as used in mobile phones) powers an electric motor. Positively-charged lithium particles pass between a graphite anode and a metal oxide cathode, generating current.

History in London The first electric battery buses began service in 2013. Two were manufactured by Chinese company BYD (Build Your Dreams) and used on routes 507 and 521, operated by Go Ahead. The first double-decker all-electric bus entered service in 2016, operated by Metroline on Route 98

How many are there now? As of 18 May there were 515 all-electric buses, according to the Mayor’s answer to a question by Caroline Pidgeon.

Which routes do they run on? Routes served by electric buses include the 507 and 521 in Central London, the 43 Friern Barnet to London Bridge Station, the 134 North Finchley to Warren Street, the 98 Willesden to Red Lion Square, the 108 Stratford International to Lewisham, the 312 South Croydon to Norwood Junction and the H98 Hounslow to Hayes.

Range Electric buses can run for 160 miles on a single charge. They tend to be charged overnight for 4-8 hours, but new charging options are coming into use.

Emissions Zero at the point of operation. A 2021 Norwegian study, which looked at full life-cycle emissions in terms of bus and battery manufacture and electricity supply for a new fleet of electric and hybrid buses in Trondheim, found that a fully electric fleet could reduce emissions by 52 per cent compared to diesel buses. Electric buses also carry diesel fuel, to heat the bus.



How do they work? A hydrogen fuel cell works like a battery: charged hydrogen particles move across an electrolyte membrane, generating electricity. They then combine with oxygen generating energy and forming water, which, along with hot air, is the only thing the fuel cell emits. Hydrogen can form an explosive mixture in air, which means the repair and servicing of fuel cell buses is done in special workshops meeting stringent standards. Technicians wear anti-static overalls and use spark-free tools.

History in London The first hydrogen bus trials took place on route RV1 in 2002 and three came into service on that route from 2004. The number eventually rose to ten before the route was axed in 2019.

How many are there now? As of this week 20 double deckers, the first in England. Soon to be 22 when older hydrogen single-deckers come back into service.

What routes do they run on? Route 7 from East Acton to Oxford Circus

Range Wrightbus’s double-decker hydrogen bus can be driven 200 miles before a refill, and its single-decker version 215 miles. With a fuel cell bus, because refilling takes only 5-10 minutes, it is possible to offer 24-hour operation.

Emissions Only water vapour in the exhaust. In the current most common industrial process to produce hydrogen, known as steam methane reforming, natural gas is split into hydrogen and carbon dioxide. In the case of “grey hydrogen” CO2 is released into the atmosphere. With “blue hydrogen” it is captured and stored. “Green hydrogen” is produced by splitting water into hydrogen and oxygen by electrolysis, producing no carbon emissions. This is currently a more expensive process. Hydrogen buses also carry batteries, to boost power for fast acceleration and to go up hills, and they carry some use diesel fuel for heating the bus.

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Categories: Analysis


  1. Philip Virgo says:

    “Green” hydrogen is attracting investment across the world and, unlike batteries does not depend on “rare” metals produced by slave labour in third world countries.

  2. Ramon Prasad says:

    I do not agree with the use of hydrogen as a fuel on buses in London or any other city. It constitutes a safety hazard, as would any other flammable gas. I do not remember any consultation process by any London Transport Authority.

    The fact that special safety measures have to be in place for servicing of these engines shows that the safety hazard is present and will always be present. I believe that this is sufficiently serious to warrant the withdrawal of this technology before it is introduced in public spaces.

    I call on Tranport for London to withdraw this technology, before it has been introduced, on safety grounds. I do do believe that it would survive any public consultation process, on safety grounds, given that there are many safe and cheaper fuel supplies readily available.

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