The decarbonization of the aviation industry It is considered a particularly difficult challenge among climate change countermeasures. This is because large amounts of energy are required to fly an aircraft, and the energy density required per unit of weight is extremely high. According to the International Energy Agency (IEA), energy-related carbon emissions in the aviation industry have increased faster than other forms of transportation in recent decades.
Under these circumstances, researchers in the United States are exploring the development and operation of new fuels using liquid hydrogenwith the aim of making the aviation industry carbon neutral. Hydrogen fuel has a higher energy density per weight than conventional jet fuel and does not emit greenhouse gases, which are believed to be the cause of global warming. Another advantage of hydrogen is that it can be produced with almost no carbon emissions.
“There is a long way to go before a hydrogen-powered aircraft becomes a reality, but proceeding with the design of the system and the analysis of the energy infrastructure necessary for its practical use will help determine priorities for actual development” explains Darik Malapragada, one of the researchers at the Massachusetts Institute of Technology (MIT).
Malapragada and his colleagues published an article on performance metrics of hydrogen fuel systems required for regional aviation of less than 1,000 nautical miles and the impact on energy infrastructure of increased demand for hydrogen due to the proliferation of new fuels. Improving the performance of fuel cells and hydrogen tanks could bring us much closer to practical use of hydrogen fuel in regional aviation.
Stable supply of liquid hydrogen is the key
The weight increase caused by the installation of fuel cells and hydrogen fuel tanks in existing aircraft will have to be compensated by reducing the weight of the aircraft and adjusting the payload (the amount of payload, such as passengers and cargo). However, payload reduction has a significant impact on airline operations. This is because more flights are needed to transport the same number of passengers and the same amount of cargo.
According to the research team, if the fuel cell system can achieve a power per unit weight of 2 kW/kg and a fuel tank weight efficiency of 50% (the value obtained by dividing the fuel weight by the weight total including the tank), existing regional. If so, it can be operated with almost no reduction in payload. Additionally, a complete transition to hydrogen fuel could reduce aviation industry carbon emissions by up to 90%.
However, even more important than operating hydrogen-fueled aircraft is developing the energy infrastructure to produce hydrogen profitably. To supply liquid hydrogen to aircraft, production facilities, storage facilities and transportation infrastructure need to be established around the world. The researchers point out that Hamburg, in Germany, and Barcelona, in Spain, already have the necessary infrastructure to produce hydrogen, so it would be a good idea to start testing hydrogen fuel in these regions.
Efficient, low-carbon hydrogen production methods include natural gas steam reforming (a method of producing hydrogen using steam from hydrocarbons or coal) and CCS (carbon dioxide capture and underground storage). A promising candidate is a method that combines technologies. Another option is to electrolyze water into hydrogen and oxygen using electricity from nuclear or renewable sources.
Since electricity prices vary greatly by region, it may be more economical to produce hydrogen in a facility that can operate at low cost and then transport it. In any case, if the levelized cost of liquid hydrogen (total cost per unit of production) can be kept low at 3.5 euros (approximately $3.70) per 1 kg, the competitiveness of the hydrogen fuel market throughout the world is likely to be established. Europe, concludes the research team.
The commercialization of hydrogen fuel depends on technological innovation and successful cost reduction. As fuel cell production increases and fuel tanks become lighter, decarbonization in regional aviation will become even more realistic. Infrastructure developed to use liquid hydrogen in the aviation industry can also accelerate the achievement of carbon neutrality in other industries, such as land and maritime transportation.
(Edited by Daisuke Takimoto)
Article originally published in WIRED Japan. Adapted by Mauricio Serfatty Godoy.
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