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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?

#41

Post by rini17 »

Zenst wrote: post #4

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…

Concentration of rainfall into artificial lakes to generate power was already done centuries ago:

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.

Re: How much power can we expect from rainfall?

#42

Post by londons_explore »

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 guess you'd need some kind of aerodynamic design like a kite to allow a massive square meter-age to stay aloft during storms.

Re: How much power can we expect from rainfall?

#43

Post by wiredfool »

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…

This is roughly High School level physics (basic, not AP or any honors or anything).

In this particular case, there's the knowledge of the first basic law of thermodynamics (You can't win, the limiting case on energy conversion) and Kinematics, typically taught as the first half/third of physics. (Broadly: Mechanics/Kinematics, E/M, Optics and Waves)

Re: How much power can we expect from rainfall?

#44

Post by steerablesafe »

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.

Re: How much power can we expect from rainfall?

#45

Post by wiredfool »

acidburnNSA wrote: post #5
hirundo wrote: post #2

"Shockingly, and inexcusably in my opinion, the researchers only state the instantaneous power (50 W/m2) of their device..." That's not entirely fair. If Nature demanded that articles be written defensively, anticipating possible misinterpretations from non specialists, they would be very different articles with lower bandwidth for the target audience, who already know the difference between average and instantaneous…

I think it is pretty misleading if they just gave the peak device power density. As in the car analogy given in TFA, if you were to burn all 270 Calories of a single Snickers bar in a thousandth of a second, your device would have a peak power of about 1 gigawatt, comparable to a large nuclear power plant. Yet if your publication said you had made a 1 GW device instead of saying that your device could power a single…

Yeah, Dietary Calories are actually Kilocalories in engineering terms, so it's a pretty energy dense material.

Re: How much power can we expect from rainfall?

#46

Post by sbdmmg »

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…

Street-Fighting Mathematics [1]

[1] https://ocw.mit.edu/courses/mathematics/18-098-street-fighti...

Re: How much power can we expect from rainfall?

#47

Post by saagarjha »

aetherspawn wrote: post #21
acidburnNSA wrote: post #5

Earlier quoted context omitted.

I think it is pretty misleading if they just gave the peak device power density. As in the car analogy given in TFA, if you were to burn all 270 Calories of a single Snickers bar in a thousandth of a second, your device would have a peak power of about 1 gigawatt, comparable to a large nuclear power plant. Yet if your publication said you had made a 1 GW device instead of saying that your device could power a single…

I would be interested to see a food chart that described how long various things can power a home in minutes. Can a salad power a home longer than a snickers bar? Or what about a potato.

While I don’t have numbers, your questions are easy to answer: foods with more calories in them can power your home longer. A typical 700 calorie meal can, if used 100% efficiently, can power a 10 W LED lamp for about three days.

Re: How much power can we expect from rainfall?

#48

Post by saagarjha »

wiredfool wrote: post #43
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…

This is roughly High School level physics (basic, not AP or any honors or anything). In this particular case, there's the knowledge of the first basic law of thermodynamics (You can't win, the limiting case on energy conversion) and Kinematics, typically taught as the first half/third of physics. (Broadly: Mechanics/Kinematics, E/M, Optics and Waves)

In most physics courses, you’ll hit conservation of energy even before it’s presented in thermodynamics packaging. This kind of calculation should be less than a week’s worth of casual effort for someone who is familiar with algebra.

Re: How much power can we expect from rainfall?

#50

Post by bryanrasmussen »

aaronblohowiak wrote: post #35
bryanrasmussen wrote: post #29

Earlier quoted context omitted.

>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 ro…

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.
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