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How much power can we expect from rainfall?

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Re: How much power can we expect from rainfall?

#51

Post by jdietrich »

londons_explore wrote: post #42

This raises a question in my mind... Current hydroelectric systems rely on building a dam, say 50m high, and generating electricity from a large mass of water falling that 50m. Might another approach be to build a tower as high as possible, say 500m, and catch rain up there. You might catch less rain, but you'd have a lot more height. Obviously the challenge with this is getting a large catchment area very high up. I…

Dams are very efficient to construct, because you take advantage of natural valleys - erosion has done most of the heavy construction work for you. The catchment area isn't just the surface area of the reservoir, but huge areas of surrounding land. Major hydroelectric reservoirs are unimaginably vast.

https://en.wikipedia.org/wiki/List_of_reservoirs_by_volume

Re: How much power can we expect from rainfall?

#52

Post by saagarjha »

thereisnospork wrote: post #38
nstart wrote: post #18

I absolutely love the gist of the article: interpreting quantitative research is something most of us are fundamentally illiterate on. That's definitely how I feel about it at least. Others might feel differently. That said, how does one actual build skills in this area. It feels like the author is able to do this here because it's a research paper in an area they have knowledge in. How does one build up a general ab…

Fermi questions[0] (oft maligned when asked in interviews) are a good practice for this sort of thinking. Anything that is either out of range on scale, or that ducks the question, is worthy of further evaluation and at least some mild skepticism. Theranos promising hundreds of blood tests out of a thimble of blood would be the former. The article referring to Volts of electricity is like a car salesman replying to '…

> Fermi questions[0] (oft maligned when asked in interviews)

I really don’t get when people bemoan these. Do they not get that it’s supposed to be an estimation, and it’s not actually a quiz of whether you’ve memorized a seemingly useless bit of trivia? Do they not see how it can be a useful skill to have, especially in an engineering field where you frequently deal with many orders of magnitude? (If acquiring this lock takes 100 ns, am I doing this often enough for this to cause a user-perceivable delay longer than doing it single-threaded?)

Re: How much power can we expect from rainfall?

#53

Post by saagarjha »

Animats wrote: post #25

Remember the "pavement that generated electricity"? [1] Raised £2.6m by crowdfunding. Turns what they really power is "exciting brand activation". By this they mean something you step on which interrogates your cell phone and ships the identity data off for marketing purposes. [1] https://pavegen.com/

But you can click on the demo on their website and generate 3 Ws (wouldn’t it be nice if there was a convenient unit for this?) of energy fit each triangle you interact with!

Re: How much power can we expect from rainfall?

#54

Post by ainiriand »

londons_explore wrote: post #42

This raises a question in my mind... Current hydroelectric systems rely on building a dam, say 50m high, and generating electricity from a large mass of water falling that 50m. Might another approach be to build a tower as high as possible, say 500m, and catch rain up there. You might catch less rain, but you'd have a lot more height. Obviously the challenge with this is getting a large catchment area very high up. I…

I think that even if it is a good concept, this reservoir would never fill.

Re: How much power can we expect from rainfall?

#55

Post by MaxBarraclough »

londons_explore wrote: post #42

This raises a question in my mind... Current hydroelectric systems rely on building a dam, say 50m high, and generating electricity from a large mass of water falling that 50m. Might another approach be to build a tower as high as possible, say 500m, and catch rain up there. You might catch less rain, but you'd have a lot more height. Obviously the challenge with this is getting a large catchment area very high up. I…

Interesting idea. As jdietrich says, I presume the reason we don't see this is simply the question of scale and cost. If you want to catch kilotons of water, a reservoir is far cheaper than an enormous raised platform.

On the flipside, there's the question of how far down you can get the water to drop, before feeding it to your generator. This is something already taken advantage of - https://en.wikipedia.org/wiki/K%C3%B6lnbrein_Dam#Reisseck-Kr...

Re: How much power can we expect from rainfall?

#56

Post by TamDenholm »

porlw wrote: post #26

There is an interesting series of videos on Youtube about harvesting energy from gutter flow: https://www.youtube.com/watch?v=S6oNxckjEiE

ive been enjoying this video series, i especially liked the video where he built his own alternator from scratch, i found it extremely educational.

Re: How much power can we expect from rainfall?

#57

Post by saberdancer »

londons_explore wrote: post #42

This raises a question in my mind... Current hydroelectric systems rely on building a dam, say 50m high, and generating electricity from a large mass of water falling that 50m. Might another approach be to build a tower as high as possible, say 500m, and catch rain up there. You might catch less rain, but you'd have a lot more height. Obviously the challenge with this is getting a large catchment area very high up. I…

Some dams use this with their generators being situation in the valley below. I see little point to do this unless you are restricted by some other factor, for example if you are a flat country with no access to natural reservoirs or vertical drops.

Re: How much power can we expect from rainfall?

#58

Post by throwaway_pdp09 »

londons_explore wrote: post #42

This raises a question in my mind... Current hydroelectric systems rely on building a dam, say 50m high, and generating electricity from a large mass of water falling that 50m. Might another approach be to build a tower as high as possible, say 500m, and catch rain up there. You might catch less rain, but you'd have a lot more height. Obviously the challenge with this is getting a large catchment area very high up. I…

Catching much rain very high up sounds stupid but at the same time that's something that needs considering. Stupid suggestions can be made un-stupid in my occasional experience. Could you elaborate please? Genuinely interested.

Re: How much power can we expect from rainfall?

#59

Post by throwaway_pdp09 »

steerablesafe wrote: post #44
londons_explore wrote: post #42

This raises a question in my mind... Current hydroelectric systems rely on building a dam, say 50m high, and generating electricity from a large mass of water falling that 50m. Might another approach be to build a tower as high as possible, say 500m, and catch rain up there. You might catch less rain, but you'd have a lot more height. Obviously the challenge with this is getting a large catchment area very high up. I…

One can argue that these dams are already catching rainfall indirectly, from a very large area with very high efficiency.

I suspect theoretical energy generation efficiency is in disproportion to the difference in potentials (IIRC the hotter something is, the more efficiently you can extract energy from it - not more energy, but more in proportion - but IANAexpert).

So while dams may catch rain efficiently, if they were 10x higher perhaps the extra potential energy usable is more than 10x

Re: How much power can we expect from rainfall?

#60

Post by DanBC »

bryanrasmussen wrote: post #50
aaronblohowiak wrote: post #35

Earlier quoted context omitted.

You put a big tank with an overflow outlet. No impediment to downflow, smooth bursts and etc

Do 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.

Here's a nice video.

https://www.youtube.com/watch?v=S6oNxckjEiE

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