• Alongside electricity and biofuels, hydrogen is one of the few options for decarbonising transport.
• Fuel cell vehicles (FCEVs) and hydrogen internal combustion engines (H2-ICEs), are particularly suited for heavy-duty transport, long-haul trucking, and industrial vehicles.
• However, hydrogen-powered transport solutions face significant challenges, including high costs and limited infrastructure development.

Currently, the transportation sector relies heavily on fossil fuels, including petrol, diesel, jet fuels, and bunker fuels, accounting for nearly a quarter of global CO₂ emissions. Despite this significant environmental impact, fuel demand in transportation continues to grow. While hydrogen, alongside electric vehicles and biofuels, offers a pathway to a more sustainable future, its use will likely be limited to specialized applications.

At present, the hydrogen technologies for road transport – both in light-duty vehicles like passenger cars and vans, and in heavy-duty vehicles such as trucks, buses, and coaches - are fuel cells and hydrogen internal combustion engines.

Fuel cell electric vehicles (FCEVs) incorporate a fuel cell that generates electricity on-board using hydrogen and oxygen from air as its feedstock. The chemical reaction between hydrogen and oxygen is an efficient and clean process that generates electricity, with water as the only waste by-product. Each fuel cell uses a catalyst, usually containing platinum, for chemical stability and improved performance. Notable FCEV models include the Toyota Mirai, Hyundai Nexo, and Honda Clarity.

Hydrogen internal combustion engines (H2ICEs) involve the combustion of hydrogen in an internal combustion engine (ICE). They present an opportunity to adapt or retrofit existing conventional ICEs and leverage their well-established supply chains. However, their application in road transport is expected to be limited to long haulage, heavy-duty goods vehicles. Toyota showcased an experimental H2ICE vehicle in December 2021 whilst China’s SINOTRUK and Weichai launched the first heavy-duty H₂-ICE vehicle in June 2022.

Refuelling

Hydrogen-powered vehicles can be refilled at hydrogen refuelling stations (HRS) in the same manner as petrol and diesel vehicles. HRS are designed to store gas above the ground in open areas to ensure that any leaks or fires can be managed safely. The hydrogen nozzle is designed to be an exact fit with the fuel tank opening and it automatically dispenses the gas once it is locked into place with an airtight seal. Additionally, fuelling stations should be equipped with safety controls, including infra-red sensors for hydrogen leak detection, and mandatory safety distances between buildings, fuel pumps, and pipework.

The current number of hydrogen refuelling stations worldwide remains relatively low, at approximately 1,000, with over 50% concentrated in East Asian countries.

Certain regions have implemented regulations aimed at significantly increasing the number of HRSs. For example, the EU’s Alternative Fuels Infrastructure Regulation (AFIR) requires that by 2030, EU member states must ensure HRS are placed every 200 km along the core Trans-European Transport Network (TEN-T) and that each urban node has at least one station available. Also, the U.S. Department of Energy aims to support the development of HRS through various programs and policies.

Vehicle emissions

While FCEVs produce zero tailpipe emissions, H2ICEs emit nitrogen oxides and small amounts of CO₂ due to lubricating oil burned within the engine. However, the “well-to-wheel” greenhouse gas emission footprints associated with H2ICEs and other low-carbon transport alternatives depend on the source of the fuel. For instance, vehicles powered by green or blue hydrogen will have a lower carbon footprint than those powered by grey hydrogen.

Light-duty vehicles (passenger cars and vans)

Hydrogen cars are only just starting to become commercially available, with Honda, Hyundai, and Toyota each releasing models using hydrogen fuel cells. As of 2023, hydrogen cars  remain relatively scarce with only around 80,000 on the road worldwide, mainly in South Korea, US, China, and Japan. Additionally, they tend to be more expensive than similar sized battery electric, petrol, or diesel cars. The current lack of refuelling infrastructure further hampers their uptake. There is broad consensus that EVs are likely to dominate light-duty transport.

Heavy-duty vehicles (trucks, buses, and coaches)

According to the International Energy Agency (IEA), although trucks and buses represent fewer than 8% of vehicles (excluding two- and three-wheelers), they are responsible for more than 35% of direct CO₂ emissions from road transport. As a fuel, hydrogen is well suited for powering heavy-duty vehicles, particularly long-haulage trucks, as it offers a comparable range of 500-750 miles and a refuelling time of 15 mins. By 2023, the global fleet of hydrogen trucks exceeded 8,000 vehicles, with 95% of them in China. The deployment of hydrogen buses is progressing with the goal of reducing air pollution in congested urban areas, although their adoption has been uneven. These buses offer a longer range than their battery electric equivalents and can be refuelled quickly at depots. As of 2023, around 7,000 hydrogen buses were in operation worldwide, mainly in China. In the UK, hydrogen fuel cell buses are being used in Aberdeen and London in demonstration projects.

Forklifts and other material handling equipment

Among all hydrogen vehicles, forklifts are the most prevalent, with over 60,000 fuel cell-powered forklifts in operation in the US alone in 2022. For a given range, the fuel cell system - comprising a hydrogen tank, fuel cell, and often a small battery storage unit - typically takes up less space than electric battery equivalents, and only take a few minutes to refuel. The hydrogen company Plug Power currently dominates the fuel cell market in this space.

Hydrogen may also be used for powering heavy industrial, construction, quarrying, mining, and agricultural vehicles such as diggers, dumper trucks, and tractors. These vehicles often need to operate for 8 to 12 hours between refuelling, and where the weight from low-energy density of batteries may be excessive. Another drawback to batteries in these applications is that these machines are often used in remote areas with limited or zero electricity grid connectivity. However, large mining companies, such as Fortescue, are increasingly turning to electric vehicles even in the heaviest-duty of use cases.

Trains

Trains are typically powered by diesel or electricity, fed through overhead lines or a third rail. Electricity could also be generated on-board using hydrogen fuel cells. The world’s first hydrogen train, the Coradia iLint™, was launched by Alstom in Germany, marking a significant step toward sustainable rail transport. Since then, hydrogen-powered trains have seen trial runs in various countries, e.g. the FCH2Rail in Spain, HydroFlex in the UK or ZEMU in the United States, demonstrating their potential for reducing emissions. However, several planned projects were abandoned due to challenges such as cost and the need for specialized infrastructure, highlighting the complexities of implementing hydrogen technology on a larger scale.

Aviation

Using hydrogen as a fuel for passenger aeroplanes is challenging. Due to its relatively low energy density compared to kerosene-type jet fuels, it would be difficult for a plane to carry enough fuel for long-haul flights, although potentially feasible for short-haul flights. There is growing research in the short-haul flights area, with the world’s first hydrogen fuel cell powered flight of a commercial-grade aircraft completed by ZeroAvia in September 2020. Additionally, H2FLY has developed an electric aircraft powered by liquid hydrogen, and the first four piloted flights have taken place, including one that lasted for over three hours.

The UK government, in partnership with industry stakeholders, has established the Jet Zero Council to drive efforts towards accelerating decarbonisation, with the goal to deliver zero emission transatlantic flights within a generation. Similarly, the Hydrogen in Aviation Alliance (HIA) was formed in the UK in September 2023 by key players in the aviation and renewable energy sectors to explore hydrogen’s potential, especially for short-haul fights. Airbus has announced its ambition to develop and launch a zero-emission hydrogen propulsion large commercial aircraft by 2035.

Shipping

The shipping industry accounts for 3% of global greenhouse gas emissions and is considered one of the most challenging sectors to decarbonise. Cargo ships are invariably powered by heavy fuel oil, or bunker oil, which is cheap but highly polluting. Hydrogen could be used to make ammonia as an alternative fuel, that, whilst having a greater energy density, is also highly toxic. It also is a potential feedstock to manufacture low carbon methanol. On a smaller scale, there are several pilot projects exploring hydrogen-powered ferries, including the HyDIME feasibility study conducted onboard a commercial ferry operating between Shapinsay and Kirkwall in Orkney, which aims to investigate how hydrogen technologies could be safely integrated in the marine industry .

In addition to hydrogen, liquefied natural gas (LNG) is being explored as a cleaner and more immediately viable alternative to conventional marine fuels.

Space vehicles

Hydrogen was first used for space exploration by NASA in the 1960s and has remained an important part of space travel ever since. NASA and the European Space Agency use hydrogen as a propellant in rocket fuel as it is very light and burns at a high temperature. Hydrogen fuel cells are also used as a power source for spacecraft and space vehicles once they are in orbit. On the Space Shuttle, three fuel cells were used to power all the electronics in the craft with water as their by-product.