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by jmward01 755 days ago
Electric has many advantages that make a direct comparison of jet-a vs battery a little hard. First, what is the overall weight of the fuel storage/support systems plus the mass associated with getting that fuel to the engines? What about the weight of the engines and all their support systems? How about how efficiently that energy can be turned into work? How efficiently can you place the engines? What about the efficiency that you can maintain in all flight regimes? What about the volume it takes to store it? How about the cost to refuel? What about the environmental advantages (not just air pollution but noise) Finally, what about the simplicity and safety of the design?

Conventional aircraft are barely improving in any of these areas while electric is rapidly improving in all of these areas. It may take a while for batteries to get the same energy density, but there is a good chance they won't need to even come all that close before the other advantages push electric ahead.
2 comments
lupusreal 755 days ago
That's a lot of handwaving but the reality works out to jet fuel being orders of magnitude more efficient than batteries on the basis of how much of either you can get into an airplane and how far they will take you. One key factor is a load of jet fuel gets much lighter as you burn it, but batteries don't get lighter as you drain them.
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jmward01 755 days ago
One thing I have been thinking about for electric is how it may allow completely different flight possibilities that could leap ahead of what we have now. For example, extremely high altitude flight is a huge challenge for current aircraft on a number of fronts, but a big one is how do you design an engine that can produce power at extreme altitudes. The higher you go the more heat limited you are in a gas turbine engine. Electric doesn't have that issue so it may be able to push aircraft a lot higher which would enable faster/further travel for far less energy use. The energy density comparison is predicated on using that energy in exactly the same way with the same efficiencies. If long distance flight becomes 100x more efficient then the density difference isn't a problem.
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maxerickson 755 days ago
Batteries will never get anywhere close to the energy density of liquid hydrocarbons.

We are already using the best potential chemistries and are a good long ways into optimizing the physical structure.

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