Electric Planes Usher in the Second Great Age of Aviation

Re:Electric Planes Usher in the Second Great Age of Aviation by masklinn on Tuesday July 28, 2015 @09:57AM (#9961468)

> The energy density of batteries sadly lags the energy density of gasoline or kerosene

Nitpick but the energy/mass density is usually called "specific energy" to differentiate it with the more usual energy/volume "energy density".

And while a battery's energy density is pretty bad, they pretty universally have a higher density than petroleum fuels and thus even worse specific energy: the best batteries have 2 orders of magnitude worse specific energy than petroleum fuels (Li-Ion or AgZn store 0.46 MJ/kg, kerosene stores 43 MJ/kg)

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Re:Electric Planes Usher in the Second Great Age of Aviation by sokoloff on Tuesday July 28, 2015 @10:48AM (#9961859)

Thanks for that. Yes, I was concerned with "specific energy" (energy per kg, not per m^3).

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Re:Electric Planes Usher in the Second Great Age of Aviation by andrewla on Tuesday July 28, 2015 @12:04PM (#9962519)

> And while a battery's energy density is pretty bad, they pretty universally have a higher density than petroleum fuels and thus even worse specific energy

Is there a typo in there? Energy density (MJ/L) for batteries is lower than petroleum fuels by the same order of magnitude as the specific energy.

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Re:Electric Planes Usher in the Second Great Age of Aviation by masklinn on Tuesday July 28, 2015 @02:32PM (#9963579)

While batteries have very energy density compared to petroleum fuels, on average it's much better (compared to petroleum fuels) than their specific energy. Their energy density is 15 ~ 40 times lower than petroleum fuels whereas their energy density is 50 ~ >100 times lower.

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