Hydrogen Can Propel Aviation Decarbonization

Decarbonization presents a major challenge for aviation. The sector is estimated to account for more than 900 million tons of carbon dioxide emission per year—an increase of 29% compared to 2013. To achieve the net-zero emissions by 2050, stringent actions are required. The Air Transport Action Group in Europe has committed to reduction of 50% of carbon dioxide emissions compared to the 2005 levels. Aviation emits other polluting gases such as nitrogen oxides. These factors present the drivers for a switch from the current fuel fix for aviation to more sustainable alternatives where hydrogen is a prime candidate. Jet propulsion based on hydrogen combustion through fuel-cells can reduce the carbon impact of a flight between 75% and 90%. Certain market barriers need to be addressed before hydrogen can be used as an aviation fuel.

Hydrogen in Aviation Faces Techno-Economic Challenges

Challenges to hydrogen usage for aviation present themselves from a techno-economic perspective and require a collaborative effort to address. The first challenge is that the tanks for storing hydrogen in flight are bulky. Even if stored in liquid hydrogen form, which requires cryogenic cooling, storing hydrogen within the airframe is cumbersome—up to 4-times heavier than kerosene tanks. This weight impacts the range and efficiency of hydrogen-fueled flight.

Another barrier to hydrogen-based aviation are high costs. Compared to airplanes operating on kerosene, hydrogen flights are projected to be 25%-30% more expensive, costing $0.045 cents per available seat-kilometer. Furthermore, longer refueling and maintenance times will reduce the availability of the hydrogen aircraft in comparison to the incumbent fuels.

Lastly, as the demand for liquid hydrogen grows exponentially it will place a strain on the existing refueling infrastructure. At present, demand at most participating airports is expected to be low given that only short-range aircrafts can be converted. To meet this demand, liquid hydrogen can be supplied through a network of liquid fuel trucks. However, with regulatory and technological advancements scalable infrastructure is expected.

Opportunities for Hydrogen in Aviation Are Vast

Despite these challenges, hydrogen propulsion systems using fuel cells present the most energy efficient, climate friendly, and economic option for short-range and medium-range aircrafts. Increased costs of hydrogen-based flights are appeased by environmental benefits that pave a path for satisfying carbon reduction targets. Industry leaders, such as Airbus through its ZEROe program, have made pledges for introducing 100-seat hydrogen powered airlines by 2035.   

However, other stakeholders in the aviation industry perceive this timeline as slow to meet the carbon emissions target set under the Paris Agreement. Universal Hydrogen is one of the early adopters and prime movers for hydrogen usage in aviation. The company seeks to scale the introduction of hydrogen for smaller regional airplanes by 2025. The powertrain for driving the propulsion system will be assembled through partnerships with Plug Power (fuel-cells) and magniX (electric motors). Customers of Universal Hydrogen include regional airlines such as Icelandair, and Air Nostrum.

Hydrogen-Based Refueling Infrastructure for Aviation

 (Source: Universal Hydrogen)

A competitor of Universal Hydrogen is ZeroAvia. The company aims for hydrogen-based commercial flying by 2023. It has successfully demonstrated a 250 kW powerplant in a six-seat aircraft and aims to scale the technology for its 600 kW 19-seater HyFlyer II airplane.

Hydrogen propulsion has significant yet under-tapped potential for decarbonizing aerial transportation. In the coming decade, bold steps are imperative to span the realms of research and technological development, in addition to international certification and standardization of protocols.