The aeronautical industry presents an important impact on the environment, with 2% of global emissions being associated with aviation. Decarbonization efforts are thus targeting aerospace technology and looking for ways to generate a cleaner, greener industry. 

Liquid hydrogen stands at the core of this transition. Acknowledged as one of the best alternatives today to reduce the aeronautical industry’s environmental impact, companies are experimenting with incorporating cryo compressed hydrogen as a fuel, just like other industrial sectors have already done, such as liquid hydrogen power for cars.

Learn about cryo compressed hydrogen and liquid hydrogen storage, the two solutions pushing the aeronautical industry towards greener, hydrogen-based alternatives.

The role of cryogenics in the aeronautical industry

Cryogenics (substances preserved at very low or cryogenic temperatures) have long played a crucial role in the aeronautical industry, performing the following roles in aerospace systems:

  • Cooling jet engines and other components, thus avoiding their overheating
  • Cryogenic hardening of metals and certain critical components of aerospace systems. This process strengthens certain materials, preparing them for flying, and maximizing their durability 
  • Rocket fuel storage at cryogenic temperatures 
  • Providing a cleaner, greener alternative to fossil fuels 

The latter is precisely the one that is propelling the use of cryogenics in the aeronautical industry, generating a real, efficient combustible alternative to fossil fuels and thus guiding aerospace systems into a cleaner future.

Related content: Hydrogen stations for cars and their increasing presence in Europe

Liquid hydrogen: the future of the aeronautical industry

The quest for efficient propellant systems for the aeronautical industry is more and more attentive to the use of liquid hydrogen as an alternative to traditional fossil fuel options. 

Aerospace systems based on hydrogen will allow planes to be electric, as hydrogen in its liquid form will be able to generate electricity on site, while also being able to be used as direct fuel.

Current state-of-the-art research in aerospace technology has already developed superconductive aircraft engines powered by liquid hydrogen. By reducing electrical resistance, these engines will maximize their power possibilities and efficiency, propelling future aircrafts just like electric motors in cars do today. Additionally, these engines will also be in need of cryogenic substances, in charge of cooling the system. 

Some of the advantages of using cryo compressed hydrogen include:

  • It’s a light material, ideal for flight transportation 
  • Production processes for hydrogen can be powered by “green” energy sources such as wind power or solar panels
  • It promotes resilience in energy supplies. Hydrogen is often used as a buffer, being converted into electricity and back again, as well as being able to be transformed into other alternative fuels. This means the aeronautical industry would be less dependent on particular energy sources and have access to a bigger diversity of energies. 
  • Hydrogen combustion doesn’t produce CO2 emissions, as it only emits NOx as exhaust and some water vapor. Other secondary emissions (including CO, coot, unburnt hydrocarbon  and volatile organic compounds) are also avoided.
  • Compared to kerosene, hydrogen presents a high energy density, as well as a wide combustion range and flammability limits
  • It’s more stable in terms of potential combustion issues. 

Storing hydrogen in an aircraft

Because hydrogen presents a low density at ambient temperature and pressure, the most convenient way to store it is in this element’s liquid form. 

While it’s true that pressurized tanks could also present a storage solution for hydrogen in its gaseous form, space and safety reasons point towards the use of cryogenic tanks.

Liquid hydrogen storage is obtained by using cryogenic storage solutions that present effective insulation in order to maintain a temperature -252.85°C, hydrogen’s liquefaction temperature.

These solutions are already being employed in the space sector and rising as strong contenders in the aeronautical industry. 

Materials used to store hydrogen in the aeronautical industry

Hydrogen cryogenic tanks need to guarantee temperatures will remain at -253°C. Aluminum stands out as the most convenient material for the following reasons:

  • The best mechanical properties for low temperature storage
  • Perfect chemical compatibility with hydrogen 
  • Proven resistance, including resistance for low temperatures compared to other alternative materials such as steel. In fact, aluminum is part of a minority of materials whose mechanical properties are not degraded by very low temperatures
  • Lightweight. Because of its low density, it generates a lighter vacuum solution than other alternatives, such as cryogenic steel or composite tanks
  • Cost-effective
  • Avoids welding issues when incorporating friction stir welding techniques
  • It’s recyclable, adding to the aeronautical industry’s efforts towards sustainability

Keep reading: Liquid hydrogen storage: learn the basics

Offering sustainability for aerospace technology

Sustainability has become a key topic in the aviation industry, guided by growing citizen’s consciousness about the environment and increasing regulatory limitations pushing for decarbonization. 

As a matter of fact, considering pre-pandemic figures gives an idea of the industry’s responsibility for cutting down CO2 emissions. In 2019, aviation was responsible for around 5% of anthropogenic causes of global warming, according to research by Arvind Gangoli Rao et al.

Within this frame of reference, the aeronautical industry is looking for ways to incorporate greener technologies that minimize its carbon footprint while remaining cost-effective and optimized. 

Different initiatives have been launched in collaboration between the aeronautical industry and regulatory bodies in order to comply with regulations and cut down emissions. 

For instance, the European ACARE Flightpath 2050 program has set a number of sustainability targets. Some of these are reducing CO2 emissions by 75% and reducing emissions of nitrogen oxides and fine particulate matter by 90%. 

The incorporation of liquid oxygen into aerospace technology is thus directly tied to these efforts and provides the most promising alternative fuel option so far.

At Cryospain, we work to remain a key supplier for liquid hydrogen storage and accompany the aeronautical industry’s efforts towards a decarbonized future. Get in touch with us to see how we can help you

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