Hydrogen is being explored as a future fuel for aviation due to its potential to significantly reduce greenhouse gas emissions compared to traditional aviation fuels. It offers a pathway toward achieving zero emission flights, which aligns with global efforts to combat climate change.
Hydrogen can be used in aviation as a fuel for propulsion systems, either in fuel cells or combustion engines. In fuel cells, hydrogen reacts with oxygen to produce electricity, powering electric motors that drive the aircraft’s propulsion. In combustion engines, hydrogen is burned with oxygen to produce thrust. Sustainably-sourced ‘green hydrogen’ is also used in the production of Power-to-Liquid (PtL) sustainable aviation fuel (SAF), an alternative to biofuels.
Reduced greenhouse gas emissions: When used in a fuel cell, hydrogen produces only water vapor as a byproduct, resulting in zero carbon emissions. Energy efficiency: Hydrogen fuel cells can be more energy-efficient than traditional combustion engines, leading to lower fuel consumption. Energy security: Hydrogen can be produced from various domestic sources, reducing dependency on imported fossil fuels. Noise reduction: Hydrogen fuel cells produce less noise than traditional aircraft engines, potentially leading to quieter flights.
Infrastructure: The infrastructure for producing, storing, and distributing hydrogen on a large scale is currently limited and needs significant collaboration and investment to support widespread adoption in aviation.
Storage and weight: Hydrogen has a low energy density by volume, requiring larger and heavier storage tanks than traditional fuels. These technologies must be developed with minimal additional weight in order to maximise performance.
Cost: Hydrogen production and distribution costs are currently higher than those of conventional aviation fuels, although advancements in technology and economies of scale could mitigate this over time. Conversely, as hydrogen has 3 x the energy in 1kg of fuel compared to kerosene, a significant amount of the additional cost per kg can be offset by the using a lot less fuel.
Safety: Hydrogen behaves differently to kerosene and therefore standards and regulations must be created or adapted to ensure the fuel can be used and handled to the same levels of rigour and safety as kerosene is today.
Hydrogen can be produced through various methods, including electrolysis, steam methane reforming, biomass gasification, and renewable energy-powered processes. Electrolysis, particularly using renewable electricity, is considered one of the most promising methods for producing “green” hydrogen, which has minimal carbon emissions
Several research and development projects are exploring hydrogen as a fuel for aviation, but no commercial aircraft currently operate solely on hydrogen. However, there are experimental aircraft and prototypes including CAeS’ hydrogen-electric propulsion systems, as well as plans for hydrogen-powered aircraft in the future, demonstrating the industry’s interest in hydrogen as an alternative fuel. Hydrogen is a key technological pathway to decarbonise aviation.
When considering the timeline for the commercial viability of hydrogen-powered aircraft, it’s crucial to account for multiple factors. Cranfield Aerospace Solutions, aiming for hydrogen-electric-powered sub-regional aircraft by 2027, demonstrates progress in smaller-scale aviation. However, the adoption of hydrogen for larger aircraft faces complexities. Technological advancements, particularly in propulsion systems, need refining to meet the demands of larger aircraft safely and efficiently. Furthermore, extensive infrastructure development is necessary for hydrogen production, storage, and refuelling at airports worldwide. The longer timeframe associated with larger aircraft developments allows for crucial lessons to be learned from smaller aircraft that can be brought to market more quickly. These lessons span production, storage, handling, and operational aspects, ensuring a more informed and efficient transition to hydrogen-powered aviation on a larger scale.
