Hydrogen can be combusted in modified gas turbine engines or used to power fuel cells that generate electricity to power electric motors. When burned or used in a fuel cell, hydrogen only produces water vapor with no carbon emissions. This makes it an attractive option to lower the environmental impact of air transportation.
Challenges with Storing and Transporting Hydrogen
One major challenge holding back widespread adoption of Hydrogen Aircraft is finding efficient ways to store hydrogen on board planes. Hydrogen is bulky and difficult to contain compared to liquid fuels like jet fuel. It needs to be stored at cryogenic temperatures close to minus 250 degrees Celsius to remain in liquid form, which requires heavy insulation. Alternatively, it can be stored under high pressures up to 700 bars in compressed gas tanks. Both options take up more volume compared to jet fuel tanks. Aircraft designers are working on lightweight carbon composite pressure vessels and cryogenic tanks to maximize hydrogen payload capacity.
Another challenge is building infrastructure for transporting and distributing liquid hydrogen to airports. Jet fuel is relatively easier to transport by tankers, pipelines and store in large underground tanks at airports. For hydrogen, cryogenic tankers, specialized pipelines and on-site liquefaction facilities need to be developed. International standards and regulations also need to be formulated to ensure public safety in the production, transportation and handling of liquid hydrogen as an aviation fuel.
Developing Hydrogen Aircraft Engines
For aircraft powered by hydrogen combustion, engine manufacturers like Rolls-Royce and GE Aviation are modifying gas turbine engines to burn hydrogen instead of jet fuel. Hydrogen has a higher flame temperature and lower ignition energy than kerosene-type jet fuel. This requires re-engineering engine components made of heat-resistant alloys and cooling technologies. Fuel injection and control systems also need adapting for hydrogen's properties. Hydrogen-fueled engines are expected to have 15-30% better fuel efficiency than current jet engines.
A new class of aircraft powered by hydrogen fuel cells is also under development. In fuel cell planes, the hydrogen is catalytically reacted with oxygen in fuel cells to generate electricity. This electricity then powers electric turbofan or propeller engines. Companies like ZeroAvia, Hydrogenics and HES Energy Systems are actively testing fuel cell powertrains and drivetrains for cargo, passenger and unmanned aerial vehicles. The major fuel cell manufacturers like Ballard Power Systems and plug power are also collaborating to further this technology.
First Hydrogen Aircraft Projects
Some of the early projects demonstrating hydrogen-powered air transportation include:
- Airbus Zephyr - In 2008, Airbus flew this solar-powered unmanned aircraft for over 2 weeks continuously using fuel cells and no fossil fuels.
- HES-30 Oberon - In 2021, this 30-seat commuter aircraft successfully conducted its maiden flight using liquid hydrogen and fuel cell propulsion. Developed by HES Energy Systems.
- ZeroAvia HyFlyer - In 2021, this 6-passenger aircraft flew for over an hour using 600kW fuel cells. Aimed to be the world's first zero-emission commercial aircraft by 2024.
- H2Fly - A project led by European aerospace firms to develop and test a turboprop aircraft using liquid hydrogen by 2023.
- Pyranaut ICARUS - This project aims to develop a hydrogen cryogenic fuel system for mid-size regional aircraft by 2025. Led by Cranfield Aerospace Solutions.
While these are technology demonstrators and prototypes, they provide proof of concept for hydrogen propulsion in planes. The next step would involve certifying these technologies and designs for commercial aviation use.
Commercial Prospects and Adoption Challenges
Major aircraft manufacturers expect demand to grow for hydrogen-powered regional turboprop and small mainline jet aircraft in the coming decades as emissions regulations tighten. A few analysts project over 10% of new regional airplane deliveries could be hydrogen powered by 2050. Airbus, Boeing, Embraer, De Havilland and others have revealed concepts for up to 100-seat hydrogen hybrid-electric regional aircraft.
However, critical challenges remain around cost competitiveness, production scaling, fuel handling infrastructure, safety certification and pilot training/transition. Hydrogen fuel is still around 3 times more expensive than conventional jet fuel. Investments are needed to drive down costs through mass manufacturing of cryogenic tanks, fuel cells and related systems. International collaboration will also be required to set performance and safety standards for hydrogen as an aviation fuel.
While there is enthusiasm for the environmental benefits, widespread commercial adoption of hydrogen aircraft may take until the 2030s and beyond. Most experts expect conventional jet fuel or advanced biofuels to remain dominant for narrowbody and widebody aircraft in the near-term. But hydrogen could realistically capture over a tenth of the regional aircraft market in the next 10-15 years if scaling challenges are addressed. That could still have a meaningful impact on lowering the aviation sector's carbon emissions.
hydrogen has great potential as a clean alternative fuel to reduce carbon emissions from the aviation industry over the long run. Significant technology development efforts are already underway to demonstrate hydrogen propulsion systems for different aircraft types. However, transitioning from prototypes to commercial service still faces infrastructure, cost and regulatory barriers. Resolving challenges around hydrogen storage, distribution networks, fuel cell miniaturization and bringing down fuel costs will be critical to accelerate the adoption of this promising clean aviation technology. With sufficient investments and international cooperation, hydrogen could start supplementing conventional jet fuel on regional and shorter routes from the late 2020s and make deeper inroads into aviation decarbonization by mid-century.
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Alice Mutum is a seasoned senior content editor at Coherent Market Insights, leveraging extensive expertise gained from her previous role as a content writer. With seven years in content development, Alice masterfully employs SEO best practices and cutting-edge digital marketing strategies to craft high-ranking, impactful content. As an editor, she meticulously ensures flawless grammar and punctuation, precise data accuracy, and perfect alignment with audience needs in every research report. Alice's dedication to excellence and her strategic approach to content make her an invaluable asset in the world of market insights.
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