Inspiration for building something hit me when the following things happened:
I learned that small amounts of electricity can be harvested from a single drop of rainwater, both from the kinetic energy and shorting two electrodes. I don’t know the how, but I’ve seen something like 200mV from a small trickle of water from a faucet.
I moved to a place that where it rains a lot and bought a house with which I could do some experiments. This house is also on a slope.
I got a 3d printer.
I figured that I could create a small, maybe 1cm x 1cm device that could harvest 200mV when a drop of water hits it. 200mV isn’t much, but if I had 100 of them hooked together in a 10cm x 10cm square, that could be somewhere between 1-100x that voltage (though, more likely lower than that unless it’s a downpour).
Then I got thinking, well it’s water, so after the kinetic energy and whatnot has been harvested it could go into a large bucket at the top of the slope. That large bucket could then be connected to a tube that’s connected to this mini 12v dc hydro generator I bought off amazon. Of course then I could use the energy generated/harvested during the day to pump water back up to the bucket at night… (ok, would have to be a large bucket and I realize this is still small amounts of electricity)…
I guess the reason we don’t see commercial systems like this has to do with energy density. After printing and prototyping and hours of trial and error, I may arrive at a device that can harvest/generate 0-15v depending on the weather. I imagine if I were to buy some TI energy harvesting devices and put them all together, I would be able to get enough energy to charge my phone in a day, but it may set me back the price of a house and may take up the size of a room to do so.
I guess my realisitic-use case would be to take something like what I just described and use it to power some outside LEDs. Then, everytime it rains, the LEDs would twinkle, and that would kind of be neat to see. Especially if these devices were installed in something like a raingutter system with individual LEDs, sort of lighting up roughly wherever rain drops were hit. No energy stored, just used as it’s harvested. It sounds like if it did work, it would be a big undertaking and would require quite a lot of time and money to build.