5 ms·

I'm wondering if the charge generated by a rain drop could be from its static charge, rather than kinetic energy conversion? Clearly storm systems can accumula

by geph2021 3y ago

I'm wondering if the charge generated by a rain drop could be from its static charge, rather than kinetic energy conversion? Clearly storm systems can accumulate a large charge differential with the ground (i.e. lightning), but I don't know if that's the principle behind rain drop charge harvesting. Cursory googling[1] tells me electrostatic charge may be the source? 1 - https://onlinelibrary.wiley.com/doi/abs/10.1002/smll.202301568 https://onlinelibrary.wiley.com/doi/abs/10.1002/smll.2023015...

angry_moose 3y ago
I'm getting well outside of my depth here, but some starting points: Rain drops have been calculated to charge up to about 1/50 of an esu (electrostatic charge unit): https://agupubs.onlinelibrary.wiley.com/doi/10.1029/TE040i001p00079 https://agupubs.onlinelibrary.wiley.com/doi/10.1029/TE040i00... Their paper is reporting 70V, so Joule/drop is on the order of 3.7E-11 J https://www.wolframalpha.com/input?i=%282.65E%E2%88%9211%29%2F50+coulomb+*+70+Volt https://www.wolframalpha.com/input?i=%282.65E%E2%88%9211%29%... (many, many orders of magnitude below the kinetic energy per drop) It's important to note most of the research they've published is not using real rain, but laboratory generated droplets that is intended to push the harvester to the maximum.
MadcapJake 3y ago
Yes, the TENG that they refer to in the paper is TriboElectric NanoGenerators https://en.m.wikipedia.org/wiki/Triboelectric_effect https://en.m.wikipedia.org/wiki/Triboelectric_effect
jrockway 3y ago
I feel like if we want static charges there must be some sort of potential difference between the top of a large building and the bottom during a thunderstorm. Probably not, though. While we're at it, can we extract any energy from lightning? Not sure if the blocker is being able to store energy delivered over a short period of time, or if it's the unlikeliness of a purpose-built structure being hit by lightning. Probably both.
- chmod775 3y ago
  > While we're at it, can we extract any energy from lightning? Wikipedia has you covered. https://en.wikipedia.org/wiki/Harvesting_lightning_energy https://en.wikipedia.org/wiki/Harvesting_lightning_energy
  - jrockway 3y ago
    Ah, excellent!
  - z3t4 3y ago
    If we could harvest and store the anti-electrons they would be very efficient at generating heat.

angry_moose 3y ago

I'm getting well outside of my depth here, but some starting points: Rain drops have been calculated to charge up to about 1/50 of an esu (electrostatic charge unit): https://agupubs.onlinelibrary.wiley.com/doi/10.1029/TE040i001p00079 https://agupubs.onlinelibrary.wiley.com/doi/10.1029/TE040i00... Their paper is reporting 70V, so Joule/drop is on the order of 3.7E-11 J https://www.wolframalpha.com/input?i=%282.65E%E2%88%9211%29%2F50+coulomb+*+70+Volt https://www.wolframalpha.com/input?i=%282.65E%E2%88%9211%29%... (many, many orders of magnitude below the kinetic energy per drop) It's important to note most of the research they've published is not using real rain, but laboratory generated droplets that is intended to push the harvester to the maximum.

MadcapJake 3y ago

Yes, the TENG that they refer to in the paper is TriboElectric NanoGenerators https://en.m.wikipedia.org/wiki/Triboelectric_effect https://en.m.wikipedia.org/wiki/Triboelectric_effect

jrockway 3y ago

I feel like if we want static charges there must be some sort of potential difference between the top of a large building and the bottom during a thunderstorm. Probably not, though. While we're at it, can we extract any energy from lightning? Not sure if the blocker is being able to store energy delivered over a short period of time, or if it's the unlikeliness of a purpose-built structure being hit by lightning. Probably both.

chmod775 3y ago
> While we're at it, can we extract any energy from lightning? Wikipedia has you covered. https://en.wikipedia.org/wiki/Harvesting_lightning_energy https://en.wikipedia.org/wiki/Harvesting_lightning_energy
- jrockway 3y ago
  Ah, excellent!
- z3t4 3y ago
  If we could harvest and store the anti-electrons they would be very efficient at generating heat.