this post was submitted on 29 Jun 2025
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I think it is more specifically electric planes as large as commercial airline passenger planes are impossible. It has a lot to do with battery mass to energy content ratio. Kerosine is about 46.4 MJ (megajoules) per kilogram. Lithium-air batteries, for example, only have about 6.12 MJ/kg.
So, that means you need 7 times as much battery (in mass) to have the same energy content of kerosine fuel. Naively, we can maybe say that means electric planes only have 1/6 of the range of an equivalent kerosine plane.[^]
Interestingly, lithium-air batteries theoretically have the largest possible energy density for any battery at 40.1 MJ/kg.
^ The calculations are really basic and probably only slightly reflect reality (since there are many other important factors. For example, Hydrogen has a lot more energy per kilogram than kerosine, but because it is much less dense, it has much less energy per m^3 than kerosine. This has made hydrogen gas very impractical for either internal-combustion engines, or planes), but I think it gives an idea of what the problem is.
There are a lot of other factors. For example, electric motors with propellers are far more efficient than turbofans
A propeller driven airplane will also be substantially slower than a turbofan one, allowing for unswept wings and better aerodynamic efficiency
In reality, battery powered passenger planes aren’t impossible but they will definitely have a shorter range and slower speed. They are realistically only suited for regional routes.
Perfect is the enemy of good. There are so many people at least here in Europe that fly easy-jet/ryanair 1h to 2h flights, these could all still work with propeller planes. But frankly I'm just wondering why I can't get subsidized trains that would be actually affordable. Right now it remains cheaper to drive all alone in my car than get an Eurostar ticket unless I planned it months in advance (spoilers: I can't plan months in advance most of the time with my work).
Agreed. A plane that can do 200ish knots for a few hours could hit a nice sweet spot for a lot of routes