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On the road to hydrogen-powered transportation

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Hydrogen’s role in the race to decarbonize transport is accelerating

Key points:

  • Hydrogen still isn’t used much in transport
  • CPCS sees hydrogen’s rise in transport decarbonization
  • Green hydrogen part of the solution to cut the global transport sector’s GHG

Green hydrogen for cleaner transportation

Green hydrogen is used more and more to decarbonize parts of the transportation sector that are difficult to electrify, including long-haul, heavy-duty trucking, shipping, and aviation.

CPCS is seeing this in its climate change advisory, having examined the case for hydrogen trains in the UK, and low-carbon marine fuels in Canada, for example.

Governments, industries and transportation organizations around the world want to accelerate their clean energy transitions. However, they struggle to have a 360-degree, practical pathway to successfully integrate clean hydrogen into their infrastructure and transportation systems.

Also, wanting green hydrogen is easier said than done.

The hard truth is that most of the hydrogen produced today is almost entirely from fossil fuels using carbon-intensive methods. In other words, producing hydrogen emits large amounts of greenhouse gas emissions (GHG).

China is the largest consumer of hydrogen for refining, followed by the US and the Middle East. Ammonia and methanol production account for most of the industrial use of hydrogen.

Globally, the transportation industry accounts for more than 20 per cent of GHG emissions and one-quarter of final energy demand, according to a report by the International Energy Agency. Oil products provide 90 per cent of transportation energy needs. 

Electrification of transportation is an answer to cut greenhouse gas emissions and hydrogen is a practical option, but counting on electrification alone isn’t enough.

Why green hydrogen use isn’t widespread

Many reasons explain why hydrogen isn’t much accessible yet.

To produce green hydrogen, it requires large amount of electricity from renewable energy.

Also, we would need about 3,600 terawatt hours a year of dedicated renewable energy – more than the entire annual electricity production of the European Union – to replace all the current fossil-fuel based hydrogen production with decarbonized production.

Producing hydrogen with renewable energy is also expensive.

Grey hydrogen produced from natural gas costs US$0.50 to US$1.70 per kg of hydrogen while green hydrogen costs between US$3 and US$8, according to the International Energy Agency (IEA). Even with carbon capture, utilization and storage (CCUS) mechanisms that adds about US$0.50 per kg to the former, using renewables as part of water electrolysis remains more than twice as expensive.

This gap might narrow if the price of carbon increases significantly over the next few decades, leading to an increase in the cost of using fossil fuels, in addition to technological improvements that could lower the cost of renewables and electrolysers.

Fuel cells, most developed technology for transport

Hydrogen could contribute significantly more to the global transport sector’s clean energy transition. The annual hydrogen demand in transport is less than 20,000 tons, not even 0.02% of the total hydrogen demand.

Two hydrogen-based technologies are used in transportation:

  • hydrogen-fuelled engines, very similar to diesel- or gasoline-fuelled vehicles
  • fuel cells, which turns hydrogen back into electricity, thus reversing the electrolysis process. Fuel cells are by far the most developed technology and are often coupled with batteries in vehicles for practical purposes.

While 11 million electric vehicles were on the world’s roads in 2020, says the IEA, there were only 40,000 fuel cell electric vehicles. Of those, 74 per cent were passenger light-duty vehicles.

Fuel cell buses only represent 16 per cent of fuel cell vehicles stock and nearly 95 per cent of them are in China, which also leads the way in adopting fuel cell trucks with more than 3,000 in service in 2020.

Hydrogen fuel cell trucks basically use the same electric drivetrain as battery trucks, but because of their on-board hydrogen storage, they have a much longer range, need fewer stops on long routes and can be fuelled much faster. Furthermore, hydrogen storage takes up less space than batteries, thus gaining cargo capacity. 

Rail has a less harmful impact on the environment than many other transport modes. Nonetheless, the railway industry is exploring alternative fuels to help reduce its environmental impact. Some companies have adopted battery-powered engines as a cleaner alternative to diesel while others are turning to hydrogen fuel cell trains. 

Compared to electric trains, fuel cell trains have a longer range. They can provide a smoother transition and interoperability by operating the same routes and stations served by diesel trains today​.

Quick Fact: In September 2022, the Alstom Coradia iLint, the world’s first hydrogen train, travelled 1,175 kilometres in Germany without refuelling its hydrogen tank.

Fuel cell passenger trains are beginning to be seen in Europe. In September 2022, the Alstom Coradia iLint, the world’s first hydrogen train, travelled 1,175 kilometers in Germany without refuelling its hydrogen tank.

The French multinational’s hydrogen trains run on southern German routes. But they are not as green as they might appear because their fuel is grey hydrogen imported from foreign oil and gas sectors.

Hydrogen’s widespread use in rail is restricted by its volume. Hydrogen storage requires considerable space, three to four times the size of a diesel fuel tank, taking over some of the passenger space.

For aviation, the first hydrogen planes are emerging, but the technology will be in competition with biofuels – a more mature sector that doesn’t require new systems to be designed or to consider a new collection of safety measures (hydrogen has a wide range of flammable concentrations in air, and lower ignition energy than gasoline or natural gas, which means it can ignite more easily).

For shipping, prototypes of hydrogen fuel cell vessels have been demonstrated for short-range travel. But more attention has been focused on ammonia-fuelled maritime engines – ammonia produced with green hydrogen. ​Methanol, which also requires hydrogen to be synthetized, is a more mature fuel than hydrogen and ammonia for the maritime sector.

Transition to clean transportation infrastructure systems

In the race to decarbonize transport, hydrogen’s role is increasing and experts at CPCS are examining its feasibility in transportation projects.

As more governments and companies aim to move towards their green hydrogen future, experts are needed to evaluate the market and its potential. CPCS

In short, for green hydrogen to significantly contribute to clean energy transitions, industries need to replace their current hydrogen supply by greener, less carbonized ones. In addition, green hydrogen is starting to compete with electrification to decarbonize some transport sectors.

Quick fact: The transportation industry accounts for more than 20 percent of greenhouse gas emissions and one-quarter of final energy demand, according to the IEA



Hydrogen basics

Hydrogen is the most abundant atom in the universe.

In plain language, the term hydrogen almost always refers to dihydrogen (H2), a molecule made up of two atoms of hydrogen. The dihydrogen molecule is very rare in nature and must be physically produced before it can be consumed.

According to the International Energy Agency (IEA), 90 million tons of hydrogen were produced in 2020. Some 72 million tons (about 80 per cent) came from specialized hydrogen production units, and 20 per cent was hydrogen produced as a by-product in facilities intended for other purposes. Of that 80 per cent, about 60 per cent came from natural gas processes and 20 per cent from coal. 

Hydrogen rainbow explained

There are other, cleaner ways to produce hydrogen and, even though hydrogen is invisible, colours have been used as a communications tool to tell them apart.

Quick Fact: Hydrogen produced with natural gas (methane) is called “grey” hydrogen.  Steam methane reformation is the dominant method to produce hydrogen from methane and this technology requires significant amounts of energy to bring the methane to 700 degrees Celsius.


“Black” hydrogen produced through coal gasification, is mostly used in China, the world’s largest hydrogen producer. Carbon emissions basically double for the same amount of hydrogen produced.

To reduce associated CO2 emissions, new hydrogen production technologies have been developed, notably “green” and “blue” hydrogen.

“Blue” hydrogen consists in adding carbon capture, utilization and storage (CCUS) to grey and black hydrogen production processes. The carbon is either used use as a resource to create products or services, or it is permanently stored deep underground in geological formations. But it’s impossible to eliminate 100 percent of CO2 emissions generated in this process, therefore 1 to 4 kg of CO2 emissions per kg of hydrogen remain

“Green” hydrogen from renewable energy

Hydrogen can also be produced through water electrolysis – a process that splits water into hydrogen and oxygen using electricity. The reaction takes place in a unit called an electrolyzer. If the electricity comes from renewable energy, then the produced hydrogen is referred to as “green” hydrogen and emissions are reduced to 0.5 to 1 kg of CO2 per kg of hydrogen.

Other colours were added to describe production with other electricity sources including “pink” hydrogen using nuclear electricity, “yellow” hydrogen, which achieves electrolysis solely through solar power. Finally other decarbonized technologies are emerging such as “turquoise” hydrogen produced by a new technology that splits natural gas or biomethane directly into hydrogen and solid carbon.

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