CLEAN AVIATION: Embracing Clean Aviation - hydrogen-powered aircraft technologies shaping a sustainable future

By Sebastien Dubois, Head of Programme Development and Communications, Clean Aviation Joint Undertaking (pictured)
Autumn 2023

Green hydrogen shows real potential to power aviation. On what areas does Clean Aviation focus its efforts?

Sebastien Dubois, Head of Programme Development and Communications, Clean Aviation Joint UndertakingHydrogen presents several major advantages in achieving the goal of climate-neutral aviation. It allows for the complete elimination of CO2 emissions during flight and throughout its entire life cycle when produced using a carbon-free process. However, it is not without its challenges, and we cannot bet solely on one horse or only on one solution for sustainable aviation.

Our €4.1 billion programme, cofunded by the European Union, explores innovative hybrid-electric concepts, ultra-efficient aircraft architectures, and disruptive hydrogen-powered technologies for the next generation of aircraft. Our innovative technologies will help reduce net emissions of greenhouse gases for commercial air travel by no less than 30% for short-medium and for regional range compared to the best aircraft models available today. Our programme's PHASE 1, running until 2025, focuses on the identification of high-potential technologies and disruptive aircraft concepts. PHASE 2 will integrate and demonstrate by 2028 – 2030 their potential impact to reduce greenhouse gases and support the launch of disruptive new products entering into service by 2035.

Concerning hydrogen propulsion to power future aircraft, we focus our efforts on hydrogen-direct burn and fuel cell-based propulsion. The first means replacing kerosene by hydrogen, and the second covers the potential of mixing both oxygen through the air and hydrogen to produce electricity. Beyond such propulsion concepts, we are also looking at hydrogen storage on board aircraft. We need to look at the aircraft architecture, define the storage device but also make sure to be able to keep the liquified hydrogen at the very low temperature of – 253 degrees Celsius. Other challenges to be addressed in synergy with Clean Hydrogen are how to re-fuel, how to integrate it all into airport infrastructure and of course ensure that everything is safe both on the ground and during flight. That is why the European Union Aviation Safety Agency (EASA) participates in our projects to comply with certification requirements.

Overall, I am proud to say that Europe is one of the world leaders in pursuit of sustainability goals. Our work supports the European Green Deal and will benefit from ReFuelEU Aviation. This European initiative aims at accelerating the scale up and production of sustainable aviation fuel, also comprising hydrogen. Moreover, our research into disruptive technologies matches our ambitions as a founding member of the Alliance for Zero-Emission Aviation (AZEA).

What are some key examples of Clean Aviation projects related to hydrogen?

Our programme's first PHASE is organised around two calls for proposals. Call 1, with a budget of €1700 million composed of EU funding (€654 million) and private members contribution, brought together a wide array of public and private partners, research centres and academia from all across Europe to work on 20 daring projects. Six of them are dedicated hydrogen-powered aircraft projects, representing 24% of the total effort of the call 1.

The CAVENDISH and HYDEA projects, led by Rolls Royce and Avio Aero respectively, cover the maturation of hydrogen direct-burn concepts. The Honeywell-led NEWBORN project looks at the next generation of high-power fuel cells. Aciturri leads the H2ELIOS project, which looks at the necessary technologies required to store hydrogen on board. The last two projects, FLHYing Tank and HYPOTrade, led by Pipistrel, are investigating all aspects related to hydrogen storage on board and the potential of fuel cells for use and testing on smaller aircraft during flight.

Our second call for proposals, with €152 million in EU funding (€380 million of budget), complements our first call projects in preparing all the necessary elements for ground and flight test activities. Three topics are specifically dedicated to hydrogen powered aircraft.

They will investigate topics such as engine and aircraft fuel distribution systems, as well as a multi-megawatt fuel cell propulsion system. I am eager to see the results of these projects, which will help pave the way for the entry into service of new highly efficient aircraft by 2035.

How important is collaboration to reach shared climate-neutrality objectives?

Clean Aviation will not succeed on its own. The required investment in reducing aviation's footprint is substantial, hence we bring key players in the aviation field together.

It is important to collaborate at European, national and regional levels. Last year, we signed a Memorandum of Understanding with EASA and another one earlier this year with the Clean Hydrogen Partnership to strengthen cooperation with key players on research and innovation. We are also liaising with national authorities in France and Germany, with more to come, to streamline efforts.

At regional level, we have recently signed Memoranda of Cooperation with the Campania region in Italy and the Occitanie region in France to accelerate the maturation and demonstration of low-emission aircraft technologies. As often said by Axel Krein, Clean Aviation Executive Director: "we need to fly in formation".

We simply cannot fail to meet our climate neutrality objectives by 2050 and have a future where clean air transport is the norm.

AREA ZERO – Alliance for Renewable Energy in Agriculture and Zero Fossil Energy

The Alliance is a collaboration of six EU-funded projects working together on solutions to overcome current challenges still facing agricultural and livestock farming sectors.

Our main objectives are to enhance the collaboration toward improvement of energy efficiency in the European agriculture; maximize the impact and improve the quality and the relevance of the outputs generated by each of the projects conforming the alliance; and contribute to the 2050 climate goals of the European Union.

AREA ZERO is an alliance bringing together four projects funded by the European Union under Horizon 2020 Research and Innovation Programme, which aim to work together for implementing technologies, techniques or strategies toward lower harmful emission, cleaner energy and improved energy efficiency in the agricultural sector.


AgroFossilFree – Strategies and technologies to achieve a European Fossil-energy-free agriculture

To feed a growing world population, the global food system needs to reduce its dependence on fossil fuels. A shift to an 'energy smart' model will safeguard the agri-food system, which is currently impacted by the high and fluctuating prices of fossil fuels and the risk that fossil fuels may not be available in the future. The project evaluates the current status in EU agriculture regarding energy use and assess existing needs, allowing farmers to optimize agricultural production through more efficient energy use and reduced GHG emissions, resulting in economic, agronomic and environmental benefits. AgroFossilFree brings together key stakeholders to evaluate and promote currently available fossil energyfree technologies and strategies (FEFTS) in EU agriculture. The goal is to close the gap between the available FEFTS, either commercial or from applicable research results, and everyday EU agricultural practices. The results assist in the creation of policy recommendations and the promotion of viable strategies and technologies.

The project has also created a Decision Support Tool, based on Artificial Intelligence, to provide an initial ranking of the technology categories best suited for each user that visits the tool. The tool mimics the consultation process of a series of experts as if they were evaluating and ranking the input data provided by the end user in order to propose the most interesting interventions for each farm. The Decision Support Tool allows to improve the visitor's experience by guiding them to the most suitable FEFTS for their day-to-day farming use.


This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 101000496.

RES4LIVE – Energy Smart Livestock Farming towards Zero Fossil Fuel Consumption

The farming industry inherently relies too heavily on unsustainable fossil fuels. The EU livestock sector is a significant contributor to climatic change, a driver of landuse change, is dependent on fossil energy sources, and a significant emitter of greenhouse gas (GHG) emissions. However, there is no need to maintain this harmful and non-sustainable strategy. It is currently feasible to achieve sustainable farming that is efficient, cost effective and low maintenance. In recent years, EU policy has focused on improving environmental sustainability and animal welfare of livestock production to achieve the goals set out in the European Green Deal. This signifies a transformation of the industrial sector in the near future.

In the RES4LIVE project, farmers in Belgium, Italy, Germany, and Greece are teaming up to illustrate the potential for livestock farms to reduce their fossil fuel dependence and implement renewable energy solutions. At the same time, it should be ensured that the applied sustainable energy practices do not come at the expense of animal welfare and comfort.

Sustainable farming in action: RES4LIVE incorporates a variety of renewable energy installations into four different pilot farm projects: a poultry farm in Greece, pig farms in Belgium and Italy, and a dairy farm in Germany. The selected technologies include PVT systems, PV panels, modular heat pumps, biogas upgrading to biomethane, biomethane-fuelled tractors, smart energy control systems and electrically powered on-farm machinery.


This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101000785.

HyPErFarm – Hydrogen and photovoltaic electrification on farm

Reinventing agriculture is essential to aim for a climateresilient future. While traditionally known for food production, the agricultural sector can concurrently function as an energy source, without causing any harm to its primary role. With photovoltaic (PV) technology now as competitive as wind power, the sector is poised to dramatically revolutionize renewable energy generation. Yet, the current model of sprawling PV-parks demands vast land areas, inadvertently displacing land once used for farming. The solution? Enter agrivoltaic systems, a dual land-use innovation that seamlessly integrates crop production with power generation.

HyPErFarm brings together diverse stakeholders with a singular mission: to optimize and validate agrivoltaic business models in 3 different pilot sites (Belgium, Denmark and Germany). This innovative approach incorporates cutting-edge PV technologies, such as PV H2-production and bifacial PV-panels, into radically new crop production systems. Through stakeholder innovation workshops, public perception analysis, and farmer adoption studies, HyPErFarm aims to test the marketability of its products and gauge citizen-consumer acceptance. Moreover, the consortium is exploring new methods of harnessing and distributing the on-farm energy produced through heat pumps, e-robots, hydrogen production, storage and use, and e-driven pyrolysis of biomass side-streams. The latter not only captures carbon but also enhances soil quality.

HyPErFarm's potential impact is profound. By elevating agrivoltaic systems to TRL7-8 and crafting appealing business models, the project enables farmers to participate in this transformative innovation. The overall vision? A low fossil-carbon, climate-resilient future for EU farming that can also power local communities with clean energy and hydrogen.


This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101000828.

TheGreefa – Thermochemical fluids in Greenhouse Farming

TheGreefa focuses on improving energy and resource efficiency in the greenhouse sector. The main challenge for the sector currently is high energy consumption for heating in Central Europe and water quality improvement in the South Mediterranean and storage of goods. The project aims to recover heat and water from the air and to create optimal climate conditions in the greenhouse. To minimise heat losses through ventilation, a technology for humidity control, heating and cooling in one system is being developed. This system utilises the absorption process using thermochemical fluid (TCF) to recover heat from the air and provide storage for the greenhouse’s needs for heating, cooling, humidity control and water recovery. In another application, the absorption process produces dry air, that can be used for low temperature dying of herbs and fruits without losing their qualities, such as smell or taste.

Another TheGreefa solution is the regeneration of TCF, allowing it to absorb humidity again. This can be achieved by using low temperature renewable energy or residual heat. The regenerated TCF can then be transported and stored for extended periods without energy losses. The developed technologies are tested in two demonstrators – in Switzerland for heating and in Tunisia for cooling, water recovery and desalination. The implementation of the technologies in the greenhouse sector will result in reduced energy and water consumption, cost savings for the greenhouse owners and enhance the use of renewable energies.


This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101000801.