The transition to low carbon flying - Status, challenges and prospects of drop-in liquid fuels, hydrogen and electrification in aviation

Aviation fuel demand is expected to continue to grow over the next decades and continue to rely heavily on kerosene fuel for use in jet engines. While efficiency and operational improvements are possible ways to reduce greenhouse gas (GHG) emissions, decarbonisation will need to heavily rely on low carbon kerosene drop-in alternatives. Currently, alternative fuels make up a very small share of fuel used in aviation, but their commercialisation is making good progress. Renewable drop-in kerosene is an attractive decarbonisation option for aviation because it does not require modification of the aircraft airframe and engine and refuelling infrastructure. Today it is commercially produced in low volumes for use in commercial flights from a limited number of airports. Its production cost is currently significantly higher than the fossil kerosene price, representing the main challenge to its uptake, which will depend on strong policy support. While hydrogen is a very appealing fuel that can be derived from a range of renewable sources and produced from fossil sources with carbon capture and storage, its use in medium and long-haul aircraft requires a radical redesign of the engine and airframe, as well as the fuel supply chain, including on-the-ground storage and refuelling, leaving it a prospect for the longer term. Hybrid and full electric aviation are gaining traction with several projects and prototypes being developed to demonstrate the technology and trial new aircraft concepts, involving research organisations, small companies, as well as major aircraft manufacturers. Small full-electric planes (up to 10-seaters) are likely to see commercial deployment in the near term. But, the technical requirements of medium and long-haul aircraft (weight, seat capacity, speed and range requirements) cannot be met with current battery technology. Without a breakthrough in battery chemistry, electric propulsion is unlikely to be used in commercial aviation beyond the smaller short-haul flights. However, as technological progress is made, hybrid electric solutions could emerge for larger aircraft, furthering hybrid powertrain and airframe integration and contributing to the reduction of fossil kerosene use in aviation. E4tech has been asked to contribute a review of the status, challenges and prospects of alternative fuels and electrification in aviation for the Johnson Matthey Technology Review. A copy of the paper is available here.

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