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I looked at this area a few decades ago and two approaches stood out as potential, though not stand out. 1) Roofs already collect a large surface area and funn
by Zenst 7y ago
I looked at this area a few decades ago and two approaches stood out as potential, though not stand out.
1) Roofs already collect a large surface area and funnel into a single point via roof guttering - so tapping the flow from the gutter run off would enable a viable volume of water turn a motor in the drain pipe as it descended and generate power.
2) Piezo electric generating from the roof, though was looking at a form of artificial grass format that would capture the wind as well as the rain hitting it, generating the vibrations to the base which would be a piezo element.
The first idea, maybe has some traction, though the volume of water (yearly rainfall) with roof surface area and the napkin maths didn't show a huge gain and bit of a limited market due to rainfall you would need to generate anything noticeable.
Second idea, kinda got mooted as roofs solar panels did better with the real-estate, and whilst for non south facing or some area's it may well been useful. Then the area's were solar is not as good due to latitude, well, then you have snow. So I kinda self-killed that avenue off as well.
Figured that tapping the drainage flow of water from a whole area combined would work better and for that need a organised drainage system all connected and yes you do get those. Though they are also the sewage system and with that, the cleanish flow of rainwater would be less common once you factor in the rest of the mix.
But I'm all for micro based generation, like a wall of small wind turbines instead of one large one and more aesthetic and palatable to add to existing buildings and area's.
- chrischen 7y agoWouldn't the water back up and then you'd have to somehow contain a ton of water on your roof?
- hannasanarion 7y ago>Figured that tapping the drainage flow of water from a whole area combined would work better and for that need a organised drainage system all connected and yes you do get those. If I'm not mistaken, the technical term for these broad-area drainage systems is "river"
- SlowRobotAhead 7y agoI think you’re on to something there. What if we made on very large, and collected lots of water at a central point and could control how much of it we use for electricity? It’s a damn good idea.
- csours 7y agoIt will never work! The collection structures will fail left and right, the surrounding soil will be saturated and cause mudslides, you'll have to evict a bunch of people and buy their land, and besides, what about the downstream farmers? They don't give a dam!
- neltnerb 7y agoHow will salmon get back up into the gutters to spawn?
- PopeDotNinja 7y agoJust unleash a horde of 1st level characters to go XP grinding on the salmon, and the salmon will simply respawn after a few minutes.
- chabes 7y agoSalmon tubes!
- pintxo 7y agoCannons: https://youtu.be/l9qA8c-E_oA https://youtu.be/l9qA8c-E_oA
- pintxo 7y agoYou mean like a 250m high wave? https://en.wikipedia.org/wiki/Vajont_Dam#Landslide_and_wave https://en.wikipedia.org/wiki/Vajont_Dam#Landslide_and_wave
- Zenst 7y ago
- neurocline 7y agoA roof is about 200 m^2 (more or less), so at 10 mw/m^2, you could generate a whopping 2 watts. While it's raining. California gets 563 millimeters of rain a year, so you might end up generating an entire 100 watts. For the year.
- NobodyNada 7y agoA watt is a unit of power, not energy —- it represents the rate at which energy is produced (joules per second), not the total amount of energy produced. I’m not sure how you came up with the number 100, but the units for that number should be energy (such as joules or watt-hours).
- neurocline 7y agoMeant to type watt-hours for that last sentence. Thanks for catching it.
- adrianN 7y agoThe first question one should ask is whether one can reasonably expect to make back the energy embodied in the generator. For example, strapping a generator to a stationary bicycle is unlikely to reach this point. Small scale wind turbines have a similar problem [1]. I really doubt that generators in individual houses drain pipes would be viable. [1] http://theoildrum.com/node/6954 http://theoildrum.com/node/6954
- lxmorj 7y agoMost of the potential energy of rain is wasted as it falls through the sky. What you really want is a huge funnel held up by enormous hydrogen balloons that catches the rain directly from the cloud, and miles-long hose coming out of the bottom. Then you'll get some real bang for your buck!
- braythwayt 7y agoOr you could just pile a lot of rock on top of rock, as much as five miles high if you like. Make a wall of this stuff hundreds or even thousands of miles long. Warm clouds full of evaporated water would hit it, be forced up into colder air, and release the water. It would then run down the rockpile and freeze, but the ice would flow down to warmer air closer to the surface, where it would melt amd you could harness the energy of the aggregated raindrops as they flow back to the sea. If “building the wall” is politically unfeasible due to liberal tears, you could find some drifting continent and get it to smash into another continent. Wait a while, and the continents smashing together will make the wall for you. No need for balloons, just be patient.
- bryanrasmussen 7y ago>Roofs already collect a large surface area and funnel into a single point via roof guttering - so tapping the flow from the gutter run off would enable a viable volume of water turn a motor in the drain pipe as it descended and generate power. the purpose of a gutter is to direct the water to areas where it can seep into the ground without damaging the house (while carrying away leaves and other things that would rot and damage the roof), at least where I live, a motor in the drain pipe would slow down the gutters in its function, which you don't want to slow down in some of the rain you get in Denmark, and finally would leave it open to more easily blocking the drain. Of course one could put a guard up on the gutter to keep large things from coming down but as I understand it gutter guards aren't really a good idea https://www.cleanproguttercleaning.com/are-gutter-guards-worth-it/ https://www.cleanproguttercleaning.com/are-gutter-guards-wor... (from a company trying to sell gutter cleaning services so maybe should be taken with grain of salt but the arguments sound pretty reasonable) and at any rate I believe would still have to let things through that would be problematic for the motor to have through. So essentially having a motor in the gutter for generating energy would mean the gutter could no longer be able to perform its function as a gutter and a new way to handle that would need to be devised.
- edaemon 7y agoCouldn't you just make the drainpipe longer to ensure the water is carried far enough from the house?
- aaronblohowiak 7y agoYou put a big tank with an overflow outlet. No impediment to downflow, smooth bursts and etc
- bryanrasmussen 7y agoDo you have a link to the thinking behind it/how it would work, would this be good for a house as opposed to a bigger building? I'd like to see if there is a solution that would match my house, although I don't think there would be.
- starpilot 7y ago> But I'm all for micro based generation, like a wall of small wind turbines instead of one large one and more aesthetic and palatable to add to existing buildings and area's. The problem with these is terrible efficiency as you scale down, due to fluid dynamics and the added redundancy from having multiple small units rather than one large one. This is why generators are huge.
- starpilot 7y agoYou could build this grand gutter power generator and have power that costs 100x more $/kWh than your grid hookup.
- EGreg 7y agoHas anyone seen piezoelectric shoes that have wires running up your pant legs to charge stuff? Could be good for the outdoors and off the grid lifestyle. Probably charges way faster than solar.
- pjc50 7y agoThe efficiency of wind turbines and their area for capturing wind goes up with size, so a single large one is better than lots of small ones. Which is why domestic ones have not become popular except off grid.
- mikro2nd 7y agoNot to mention that small wind turbines are quite noisy.
- rini17 7y agoConcentration of rainfall into artificial lakes to generate power was already done centuries ago: https://www.banskastiavnica.travel/en/what-to-see/stiavnicke-tajchy/ https://www.banskastiavnica.travel/en/what-to-see/stiavnicke... The mine drainage system was later gradually replaced with steam engines, however there is a ~megawatt hydropower electrical plant still functional.
- CraigJPerry 7y agoRoof line guttering is only about 8 metres high on residential property. 8 meters doesn’t seem like much potential energy for something that weighs 1kg per litre “processed”, that energy source isn’t going to run anything interesting at all
- pintxo 7y agoFunny no one has cited Randals What-If yet: https://what-if.xkcd.com/23/ https://what-if.xkcd.com/23/ (third question on the list) Back of the envelop calculations would have break even after about 100 years...