The UK Civil Aviation Authority (CAA) has launched a second round of its Hydrogen Challenge program, which aims to foster industry collaboration to boost the adoption of hydrogen propulsion by the air transport sector. Announced on February 3, this round is expected to expand the scope of existing research and development work and operational trials.

According to the CAA, the next stage of the Hydrogen Challenge will cover four areas of work involving companies and academic institutions. These include the following: new aircraft designs combining fuel cell-based hydrogen propulsion systems and remotely-piloted operations; airport infrastructure changes, including fuel storage and delivery provision; new scientific research into hydrogen fuel; and a series of flight trials, safety assessments, and demonstrations to refine operational performance and address regulatory challenges.

The first round of the Hydrogen Challenge was launched in 2024 and already involves more than a dozen organizations. Results from the 2024 work are set to be published soon, and the next round of trials will last three years.

Among the programs already part of the CAA’s Hydrogen Sandbox is Cranfield Aerospace Solutions’ Project Fresson, which is focused on converting aircraft such as the Britten-Norman Islander to use a hydrogen propulsion system. ZeroAvia’s work to convert existing regional airliners is also part of the program, with work covering hydrogen fuel storage, distribution, and refueling processes.

Swift Aircraft is exploring the use of hydrogen fuel for a new generation of training aircraft, and QDot Technology is developing long-range, high-payload uncrewed aircraft for applications including logistics, monitoring, and offshore energy installation support. Several UK airports are involved in the Hydrogen Challenge, including Kirkwall Airport in northern Scotland, where Loganair is evaluating hydrogen-based regional air services, and Exeter Airport in the southwest of England.

Aircraft engine manufacturer Rolls-Royce is developing gas turbines that could run on hydrogen fuel through a partnership with low-cost carrier EasyJet. Other program participants include Oxford University, the HyFive consortium, Stratospheric Platforms, Intelligent Energy, and Ultima Forma.

“These trials keep the UK on course to be a world leader in hydrogen propulsion,” said Tim Johnson, director of communications, strategy, and policy at the CAA. “We are working with some of the most innovative companies and minds to better understand this technology and how it might be introduced safely in the aerospace sector. In doing so, it offers the potential to enable a more sustainable aerospace system and support UK economic growth.”