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PragmaticSquirrel t1_irxhgsj wrote

Reply to comment by astroNerf in NASA invents ‘incredible’ battery for electric planes by HaikuKnives

Any idea what the energy density is compared to kerosene (jet fuel)?

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GaryQueenofScots t1_irxp4mn wrote

Nasa claims 500 Watt-hours/kilogram in their solid state battery, or in other words 1.8 MJ/kg. Kerosene is rated at about 42 MJ/kg (and gasoline is about 44 MJ/kg) so there's a factor of 20 between them. Thats actually not as bad as it sounds, considering that electric motors are much more efficient at energy conversion than combustion engines that would be used to drive a prop.

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shoulderknees t1_irxqw4r wrote

One other important element is that you get rid of your kerosene as you use it, reducing your mass and thus your propulsion need. But your battery is still there at the end of the flight.

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PragmaticSquirrel t1_iry0tq4 wrote

Thanks, that's really interesting - it looks like electric motors are about 2X as efficient as gas? So this tech would mean that the overall non-waste energy density is about 10X?

That does seem like it's starting to get in the same ballpark, even if it is still somewhat distant.

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EimaiOTed t1_irzvgnb wrote

What would be a good way to normalize this? Newton * second / gram of fuel considering a typical jet turbine and an electric one?

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