As the world searches for new ways to combat climate change, hydrogen has emerged as a potential saviour for many polluting industries, including aviation. The aviation industry accounts for approximately 2.5% of global carbon emissions. These emissions are expected to soar in the coming decades, unless changes are made to aircraft fuelling and operation. Despite the current focus on electrification and batteries as alternative solutions, hydrogen is a strong contender to be the sustainable aviation fuel of the future.
Advantages of hydrogen-powered aviation
Hydrogen and air travel have a complex relationship, with history buffs quick to point out the 1937 Hindenburg airship disaster. The Hindenburg, which contained more than 70,000 tonnes of hydrogen, caught fire and crashed, causing the deaths of 35 people. The Hindenburg was however not fuelled by hydrogen, but merely used the gas to provide buoyancy.
In the past 85 years hydrogen powered aviation technology has progressed and the advantages of using hydrogen as an aviation fuel are now evident.
Hydrogen-powered aircraft emit only water and tests suggest they can be just as fast as regular planes, carrying over a hundred passengers per flight across thousands of kilometres. Hydrogen propulsion would significantly reduce climate impact as it eliminates carbon dioxide (CO2) emissions in flight and can be fully carbon free when green hydrogen (produced using a process called electrolysis) (GH2) is used as a fuel source.
A recent report on the potential of hydrogen-powered aviation, noted the following:
| Aircraft type | Commuter | Regional | Short-range | Medium range | Long range |
| Propulsion power | Fuel cell system | Fuel cell system | Hybrid | H2 turbine | H2 turbine |
| Passengers | 19 | 80 | 165 | 250 | 325 |
| Range (km) | 500 | 1,000 | 2,000 | 7,000 | 10,000 |
| Cruise speed (km/hr) | 500 | 543 | 889 | 1012 | 1050 |
| Energy demand | -10% | -8% | -4% | +22% | +42% |
| CO2 reduction | 100% | 100% | 100% | 100% | 100% |
| Climate impact
reduction1 |
80-90% | 80-90% | 70-80% | 50-60% | 40-50% |
| Additional cost
(CASK)2 |
0-5% | 5-15% | 20-30% | 30-40% | 40-50% |
| Entry into service | < 10 years | 10-15 years | 15 years | 20 years | 20-25 years |
| MTOW3 | +15% | +10% | 14% | +12% | +23% |
- Measured in CO2 equivalent compared to full climate impact of kerosene-powered aviation
- Cost per available seat kilometre
- Maximum take-off weight
The above table demonstrates that as the size of the aircraft increases, its climate impact reduction decreases, and costs increase. Long-range aircraft require new aircraft designs to utilise hydrogen in an economic way. This is because the weight of the hydrogen tanks would increase energy demand, resulting in significantly higher costs per flight. The smaller aircraft (commuter, regional and short-range) will play an important role in developing more energy efficient, climate-friendly and cost-effective larger aircraft as technologies are tried and tested.
Progress
Hydrogen-powered aviation could potentially be realised by running liquid hydrogen through a fuel cell. Storing hydrogen in a liquid state is promising, as it offers high volumetric density compared to hydrogen in its gaseous form. A complication of liquid hydrogen storage is the necessity of cryogenic cooling, that is, cooling below -253 degrees Celsius. Liquid hydrogen storage would require planes to be remodelled as the wings on traditional aircraft cannot support the weight of the heavy insulated tanks required to regulate temperature.
Progress has been made in developing the underlying technology for hydrogen planes. In 2008, Boeing flew the world’s first hydrogen-powered plane, a two-seater glider, propelled by battery power and hydrogen fuel-cell generated energy – proving the technology is viable. In 2016, the first four-seater hydrogen plane powered solely by a hydrogen fuel cell took flight, developed primarily by Germany’s DLR Institute of Engineering Thermodynamics.
In 2022, Delta Air Lines and Airbus announced a partnership to collaborate on industry-leading research to accelerate the development of a hydrogen-powered aircraft. The two aviation behemoths will explore its technical and commercial viability, assess the infrastructure (and cost) required to develop or procure their own GH2 production and implement it at airports, and advocate for a decarbonised future in aviation with key industry stakeholders. Airbus has already embarked on designing liquid hydrogen tanks and is building a “ZEROe” demonstrator to test hydrogen propulsion in one of its A380 jets.
Plane manufacturer, Boeing, has built a cryogenic fuel tank designed for space launches that it said could eventually store liquid hydrogen on commercial aircraft. While innovation is not hard to come by, work still needs to be done to overcome the more significant barriers to take-off.
Barriers to take-off
Shifting to hydrogen as a fuel for aviation is not without its challenges and there are several barriers to overcome before take-off is possible. As a disruptive innovation, it will require extensive research and development, investment by Government and industry, and regulation to ensure safe, cost-effective and climate friendly hydrogen powered aircraft and infrastructure.
Hydrogen storage technologies will need to advance to carry enough liquid hydrogen in planes for longer journeys. A substantial increase in GH2 production is also required to produce sufficient volumes for the aviation industry and to reduce production costs. However, as demand for hydrogen from other transport sectors increases and supply rises in tandem with renewable energy capacity, GH2 costs will likely fall.
Another challenge is the modification of existing airport infrastructure, with distribution, storage and production facilities all needed at scale. This scale-up will bring its own challenges including finding more suitable refuelling technology than refuelling trucks, establishing parallel refuelling infrastructure at airports, and adapting parking stands to accommodate larger aircraft. Synergies with existing gas pipelines could be used to facilitate hydrogen transportation to airports.
To initiate a hydrogen decarbonisation path, bold steps will need to be taken. A sector roadmap to reduce climate impact, increased research and innovation activity and funding, and a long-term policy framework will be necessary to transition to a new propulsion technology. While these obstacles are significant, there are no fundamental technical barriers that would prevent implementation, if planned and addressed in a timely manner.
The sky’s the limit
Hydrogen propulsion has the potential to lessen the climate impact of aviation and contribute to decarbonisation goals. Technological development, a commitment to phase out gas and diesel aircraft, and buy-in from key stakeholders will shape the future of hydrogen-powered aviation. The benefits of hydrogen are obvious, and it offers a promising solution to significantly reducing greenhouse gas emissions.
The Hamilton Locke team advises across the energy project life cycle – from project development, grid connection, financing, and construction, including the buying and selling of development and operating projects. For more information, please contact Matt Baumgurtel.
