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RandomlyMethodical t1_is2pe6b wrote

> A novel vertical-stack design also allowed SABERS researchers to create a solid-state battery capable of powering objects at a capacity of 500 watt-hours per kilogram

That's pretty impressive. For comparison, Tesla's Model 3 battery (believed to be the most energy dense battery on the market) is estimated to be around 272-296 Wh/kg

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EccentricFan t1_is32jz9 wrote

It'd be fun to see a chart tracking the progress of Wh/kg over time, to visually see how much we're improving year to year.

Though come to think of it, that would be measured as Wh/kg per year, and if we simplified that, would it mean that battery progress of this type can be measured in W/kg?

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da5id2701 t1_is3lcpm wrote

Suppose you had a magical 1kg battery which constantly upgrades its capacity to match the state of the art battery tech. The W/kg figure would be the amount of power you have to continuously pump into that battery to keep it fully charged (ignoring self-discharge). I approve of this unit.

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safetytrick t1_is3r59l wrote

Everything can be simplified if you are willing to ignore the complexities 😭😩

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bl0rq t1_is3y16g wrote

For further comparision: jet fuel is about 12,000 Wh/kg.

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MegaHashes t1_is52tat wrote

I think this is a little bit misleading. While Jet fuel is incredibly energy dense, jet engine designs convert only 30-50% of the energy stored in jet fuel into mechanical effort.

I’m not certain what the power efficiency of an equivalent electric based propulsion device would be, but I believe the losses within electromagnetic motor designs are much lower.

That doesn’t exactly close the gap between energy densities, but it does narrow it a lot.

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pantsonhead t1_is5v651 wrote

You are forgetting that a dead battery weighs as much as a full one, whereas burned fuel doesn’t weigh anything. Any gains in power efficiency in the context of an airplane is likely to be offset by carrying extra battery weight all the time.

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hucktard t1_is6cfu7 wrote

You just have to launch the spent batteries out of the back of the airplane.

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MegaHashes t1_is9zkrl wrote

We need r/TheyDidTheMath on the case to prove that.

Commercial airliners never fly on empty, and you can’t gain more jet fuel by covering planes with solar panels they way you can with electricity.

The technology isn’t there yet, and I’m not suggesting it is. My suggestion was only that the energy density numbers don’t tell the full story because of inherent losses when using that energy source.

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BioClone t1_iskfo6y wrote

well the environmental hit, and ways to reverse it also needs to appear on the maths by the same reason.

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pantsonhead t1_islavry wrote

I guess the point is, some green energy source other than batteries is probably the solution for airplanes i.e. hydrogen/biofuels.

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beatthestupidout t1_is4v1i0 wrote

It is, but it requires pumps, heavier engines, etc. to run, and only convert their energy into motive power with around a 30% efficiency compared to the >90% of an electric motor. The batteries are catching up in real terms faster than a simple comparison of densities would suggest.

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bl0rq t1_is67xjc wrote

Modern jet engines are closer to 50%. And yes fuel pumps and whatnot have mass too. But so do the supporting things for the electric version. A electric motor about equal to a 787 engine output weighs at least as much. And both it and the battery would need cooling.

> The batteries are catching up in real terms faster than a simple comparison of densities would suggest

They are not. They are dense enough for many things (commuter cars) but not airplanes.

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iNstein t1_is3op8t wrote

I think they are referring to the power draw rather than the energy density. So it is possible they have a battery with a power density of 250wh/kg but are able to pull 500 watts from a 1kg battery for half an hour.

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