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Posted on November 11, 2024 by  & 

Heavy-Weight to Feather-Weight - Sustainable Future Aviation

The plane against the blue sunset sky. The setting sun. Sunset.
Decarbonizing aviation could be the next big step for the sustainable transportation industry, and with the popularity of both national and international travel, there is opportunity emerging for both electric and hydrogen-powered planes. IDTechEx's latest report, "Sustainable Future Aviation 2025-2045: Trends, Technologies, Forecasts", hones in on the potential, benefits, and disadvantages of batteries, hydrogen combustion engines, and fuel-cells, with focus on aircraft weight.
 
Electrifying aircrafts
 
Battery weight is one of the current barriers that companies are trying to overcome, as planes require specific take-off and landing weights that take into consideration the burning of fuel during flight. However, with today's technologies, a battery would need to weigh 10 times as much as a tank of jet fuel for the same amount of usable energy, according to IDTechEx. Once passenger and luggage weight are also taken into consideration, there is little room left to work with.
 
Up to 1000km of range may be the feasible limit for electric planes, but this will likely take a combination of increasing the maximum landing weight of planes, and waiting on more advanced battery technologies to be commercially ready. IDTechEx's report focuses on the logistics of airplane electrification alongside the variables needed to make it happen, with single aisle commercial planes of 200 seats being the most likely candidate for adoption. With 33% of seats sold in the US being on flights less than 1000km, and lots of them being extremely high volume, it makes the most sense to target these shorter distance flights where the most benefits could be seen.
 
 
Beyond battery weight, electric aircraft designers are also likely to run into issues around motor power. Turbofans are the largest type of engine used in commercial planes and are extremely powerful. They are also power dense, more so than the motors typically found in electric vehicles. Leading start-ups have motor technologies with better power densities than jet turbines, but these are typically in the region of 1-5MW, around an order of magnitude less than big turbofan engines. IDTechEx expects the absolute power of these motors to increase over time, but also expects that electric commercial airplanes will need to use many more than the two engines the industry has become accustomed to.
 
The hydrogen hustle
 
At the other end of the spectrum, hydrogen's lightweight reputation could face issues of not being quite heavy enough. Weighing about 10 times less than jet fuel, and not quite matching up in volumetric energy density, it will be difficult to get enough hydrogen onto the plane to achieve long ranges. Realistically, liquid hydrogen will be the best way to get as much energy as possible into the tanks, but this also creates challenges around liquid hydrogen's need to be cryogenically refrigerated.
 
Hydrogen internal combustion engines (H2ICE) can be achieved by adapting already existing jet turbines to run on hydrogen instead of jet fuel, with the engine still amounting to the same weight. However, NOx emissions and water vapour produced during the combustion process makes this approach not quite emission free, and in comparison to using a hydrogen fuel-cell, is not as good for the environment.
 
 
Fuel-cells are notoriously heavy, with IDTechEx estimating that a fuel cell motor propulsion engine for a commercial airliner could weigh in the region of 67 tonnes. This will also create challenges in building a fuel cell plane inside today's maximum landing weights. IDTechEx states that the extra weight required is a small enough amount that it could be worked around, enhancing the feasibility of this approach. The type of hydrogen used is also a factor for consideration. Despite green hydrogen being the most sustainable choice, it is costly to use due to inevitable efficiency losses and is more expensive than battery power, while emissions created from hydrogen produced through grid powered electrolysis would likely be worse for the environment than sticking with jet fuel, so there is really no perfect solution.
 
Funding and future outlooks
 
In September 2023 Europe saw €380 million euros of government funding approved towards the decarbonization of the aviation industry, and over US$350 million of private and government funding invested in the US in 2022, highlighting the increasing interest in this sector.
 
IDTechEx stresses the importance of strategic deployment and the need to target airports and routes that have the space and feasibility to host new infrastructure for both charging and hydrogen refuelling. With battery technologies continuing to develop and use cases on the horizon for future electric commercial planes, work needs to be done to increase maximum landing weights to ensure the planes are fit for adoption. For more information on this emerging technology, visit "Sustainable Future Aviation 2025-2045: Trends, Technologies, Forecasts" for IDTechEx's take on the future of aviation decarbonization.

About IDTechEx

IDTechEx provides trusted independent research on emerging technologies and their markets. Since 1999, we have been helping our clients to understand new technologies, their supply chains, market requirements, opportunities and forecasts. For more information, contact research@IDTechEx.com or visit www.IDTechEx.com.
 

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Posted on: November 11, 2024

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