Real Engineering
4 HN recommenders · recommended in 6 months, 2018–2024
10:24 · 2.3M views · Jul 20, 2018
Real Engineering analyzes whether electric planes are feasible, focusing on battery energy density limits compared with jet fuel. It concludes electric flight works mainly for short ranges.
HN recommends it as a clear explanation of why batteries limit electric aviation.
6 comments from Hacker News
IIRC real-engineering on youtube did a detailed analysis of the current operating limitations with electric planes: this video He also identified a couple of sweet spots where electric flight would make sense factoring in engine efficiency & cost of fuel etc. bottom line is that the picture is more complex than just comparing energy density of jet-fuel & batteries. with batteries becoming much lighter IMO it should open up many more use cases for short haul frequent flights without the need of big central hub airports. which is good. an more importantly give the trajectory of battery energy density it should provide enough justification for heavy investment into research into electric planes so i wouldn't dismiss it out of hand.
Yes, and the physics of it are even worse than you imagine. If you don't mind a voice/video explanation of this, I found this one worked for people I know [0]. In the air, there is a cascading relationship between the requirements for lift, and the weight of the fuel (batteries). Batteries being, by weight, at least between 40 and 100x times less energy dense than Kerosene, the weight of batteries competing with Kerosene multiplies the real amount of energy required to transport aircraft. This relationship doesn't hurt so much on the road, since there is generally not much need for lift, and also since there is a straightforward way of recovering the increase in inertia. [0]: this video
The big win would obviously be electric aircraft, but I doubt we'll see that in my lifetime (barring a massive breakthrough in battery technology). The problem is even the best batteries have a much lower energy density compared with traditional fuels. Also, a battery that weighs 100kg when full weighs pretty much 100kg when empty. Real Engineering did a pretty good video on the topic this video
The Youtuber Real-Engineering (aerospace engineering background) has a good video discussing the viability of electric aircraft. Barring some dramatic revolution in battery energy density, electric aircraft beyond a certain range are simply not-feasible. They are very feasible for short-range routes though. this video
Synthetic liquid methane would probably be more practical because it is so much more energy dense than hydrogen. Audi already has a pilot plant that does this. [LINK] You can also run standard jet engines on biodiesel. [LINK] Both options are far more realistic than electric airliners, which simply aren't possible with any battery technology which will exist in the foreseeable future. this video NASA's interest in electric aircraft is most likely motivated by the possibility of flying them on other planets. [LINK]