July 24, 2020, ©. Leeham News: What a difference three months make!
When I wrapped the 20 piece Corner series about e in ePlane not standing for electric, on the first of May, I was virtually alone in saying hydrogen is the best long term alternative to our airliners’ jet fuel.
Today it’s all about hydrogen, especially if you ask industry and authorities in Europe. What happened?
What happened? How can a World-wide conviction the next non-jet fuel airliner is electric turn to hydrogen in just three months? The actual turn has taken a bit longer but it happened fast. Let’s go through why.
It was all in our ePlane Corner series. There we concluded:
Why didn’t the aeronautical community realize that batteries are not an option for airliners?
Other developments gave hope and the early movers didn’t have the experience to see the challenges the airliner application presented.
What happened over the last decade was the electric and hybrid car went from a curiosity to the mainstream. The classic car makers were cornered by Tesla (100% battery) and Toyota (battery-based hybrids). Entrepreneurs wanting to be the new Elon Musk predicted the same change would happen for aircraft. After all, aircraft are driven by combustion engines, as are cars.
Those who set about cornering the aircraft industry and create the aircraft industry’s Tesla or SpaceX didn’t do their homework before presenting their Powerpoint projects. Promises of new battery-driven airliners taking over from the Boeing 737 MAX and Airbus A320 before 2030 and being 30% more efficient occupied the industry magazine pages over the last years.
Gradually, experienced airplane designer teams from the OEMs made the sums (as did I) and the impossibility of achieving anything usable with present battery technology became clear. Then investigations into progress in battery technology showed it would be a struggle, even for a short-range airliner. There’s a huge difference between the performance of a research lab battery and what can be certified as an airliner propulsion battery system.
The focus then turned to hybrids. While it was possible to make it work, the same seasoned people saw it would not bring any real gains as long as batteries were the complementary energy store to jet fuel. A very little gain for substantial technical complexity and risk.
The key realization over the last year was the battery as an energy store for airliners didn’t cut it. Not today, not tomorrow, and probably not in the foreseeable future.
The alternative energy store that was continuously looked at was Hydrogen, H2. It was the fuel the world’s first jet engine used (H. von Ohain’s He-S-2 engine in 1937) and it was the fuel used in the Russian Tu-155 hydrogen research airliner in 1988, Figure 1.
It has some very attractive features like three times higher energy density than jet fuel (batteries have 70 times worse) but also challenges like four times worse volume density and a non-existent production ecosystem for air transport.
In the next Corners, we dig deeper into the challenges for H2 and the possible solutions to handle them.
PS. For anyone that wants to revisit the ePlane articles, go to our search box, top right, and enter “ePlane”. The series is then listed with all the parts. DS.