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Comment by deegles | Hacker News Reader

The paper says a cubic meter of the material could generate more than a kilowatt (per hour?)... sounds promising if it actually gets commercialized.

I assume it would only work well in places where there are significant humidity swings, I didn't read the paper very carefully though.

https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202300...

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> more than a kilowatt (per hour?)

Not sure what you mean, Watt already has a unit of time in it.

Nope.

Watts are a rate of one joule per second.

If you want to talk about a quantity of energy rather than a rate of energy production/consumption, the units would be either kilowatt hours or joules (1 kWh = 3,600,000 joules).

Yup, kilowatt hours are a cursed unit that simply reduces to joules (a nice and easy to remember 3.6 million of them).

Yeah I have to work that out every time

The paper just says "an estimated energy density of >1 kW/m^2"

That's quite an amount, about 3-5x the amount of energy generated by solar cells of the same surface area. It would mean the device would generate $2000-$4000 on a yearly basis.

Didn’t it say cubic meter, not square?

"Energy density" is a misnomer, it should be power density, since the kW is a unit of power (rate of energy generation), not energy.

The good info is apparently in table S2 of "supporting materials", where they compare energy harvesting devices. That's not part of what you can read for free.

Some kind of energy harvesting device that could generate a few milliwatts in ambient indoor conditions would be very useful. We have lots of things with AA batteries in them that use very little power but need a new battery every year or so. That's the potential here. This isn't going to replace oil.

I got a copy, it says "~0.0001-0.05" W/m^2 for their material, which they put at the same order of magnitude as "Hydrovoltaic" harvesters, and several orders below something like wind or solar. But they do list theirs as the only 3D scalable, "continuous and ubiquitous" harvester.

Presupposing completely optimal 50mW/m^2, could you origami that surface? Because then you could probably have something pretty useful.

A kilowatt is unit of power. Joule is the unit for energy. A Watt is 1 Joule per second.

A another common unit for energy is kWh (kilowatt.hour)

A kilowatt generator can produce one kWh/h (by definition)

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