In-Flight Hydrogen Production Could Result in "Greener" Aircraft

A team of aerospace engineers at the Technion-Israel Institute of Technology have created and patented a process that can be applied onboard aircraft while in flight to generate hydrogen from water (including waste water on the plane) and aluminum particles, safely and economically.

After the hydrogen is collected, it can be converted into electrical energy for inflight use. This innovation could open doors for less-polluting, more-electric aircraft that substitute pneumatic and hydraulic systems usually powered by the main engine.

The revolutionary work was published in the International Journal of Hydrogen Energy.

Hydrogen produced onboard the aircraft during flight can be channeled to a fuel cell for electrical energy generation. This technology offers a good solution to several challenges, such as hydrogen storage, without the problems associated with storing hydrogen in a liquid or gas state.

Dr. Shani Elitzur, Technion Faculty of Aerospace Engineering

While the application of hydrogen fuels has been a probable greener energy solution for a specific period, storing hydrogen has always been an issue. The engineers overcame the hydrogen storage problem by using non-polluting Proton Exchange Membrane (PEM) fuel cells and a process of aluminum activation patented by the paper’s co-authors, Prof. Alon Gany and Dr. Valery Rosenband.

Dr. Elitzur’s research looked at the reaction between the activated aluminum powder and water (from different types) to generate hydrogen. The technology’s foundation is in the chemical reaction between aluminum powder and water to generate hydrogen. Either waste water or fresh water, already onboard the aircraft, can be used for activation, which means the aircraft need not carry any extra water.

The spontaneous and continuous reaction between powdered aluminum and water is facilitated by a special thermo-chemical process of aluminum activation the researchers created. The protective properties of the hydroxide or oxide film covering the aluminum particle surface are altered by a small fraction of lithium-based activator diffused into aluminum bulk, allowing water at room temperature to react naturally with the aluminum.

The process does produce heat, which the researchers say can be used for many tasks, including de-icing operations, heating food and water in the galley, or heating aircraft fuel before starting the engines.

According to the team, their technology would offer:

• Quieter operations on board an aircraft
• More efficient electric power generation
• Significant reductions in CO₂ emissions
• Compact storage; no need for hydrogen storage tanks onboard aircraft
• Thermal efficiency (fuel cell produced heat can be used for de-icing, heating jet fuel)
• A reduction in wiring (many fuel cells can be placed near their point of use)
• Decreased flammable vapors in fuel tanks (Inert gas generation)

The possibility of using available, onboard wastewater boosts both the efficiency and safety of the system. Also, the PEM fuel cells exhibit high efficiency in electric energy generation.

Dr. Valery Rosenband, Technion Faculty of Aerospace Engineering

Aircraft manufacturers, including Airbus and Boeing, have already examined using onboard fuel cells. Boeing has tried them out in smaller aircraft, hoping to use them on its 787-8, the current advanced electric airplane. According to the Technion researchers, fuel cells can even aid in saving energy in airline and airport ground support operations when they are used for systems such as runway light towers and de-icing.

Efficient hydrogen production and storage represents the future for efficient and safe aircraft inflight energy needs.

Professor Alon Gany, Technion Faculty of Aerospace Engineering

Source: http://www.ats.org