Aircraft and battery size
For all the talk about electric aviation, the industry is yet to figure out how to overcome a fairly hard problem – let’s call it the 40:1 problem
Batteries – even the best of them – have energy densities of only about 300 Wh per Kg. The energy density of aviation fuel is about 12000 Wh/Kg, about 40 times that of batteries.
A 200 ton (empty weight) Boeing 747 today carries around 120 tons of fuel for a long distance flight (though it has a capacity of about 200 tons). I have not been able to get precise estimates for fuel to useful energy efficiencies but I reckon it should be in the 30-35% range as we are talking gas turbines for large aircraft. Electric motors are far more efficient, about 85%. If I consider all the above, if that long haul Boeing were to run fully on batteries at 300 Wh/Kg, it needs to carry about 2000 tons of batteries.
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Is it possible for battery energy densities to increase significantly?
I’m not the expert here, but I have not seen any company envision higher than 600 Wh/Kg – that would still mean 1000 tons of batteries – no fly!
It appears that battery propelled aircraft are destined for smal aircraft, short haul routes for the foreseeable future.
See my LinkedIn post on this topic
