Generating energy from water moving through rain gutters
Image credit: This Old House
Spook LouwNov 17, 2021
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The idea is simple, I'm just not sure if it will be able to generate enough energy to be feasible.
The question is how would we be able to harness energy from rainwater?
There is already some very interesting work being done on Droplet-based Electricity Generators but my idea incorporates more conventional and established methods of harnessing hydroelectricity. Basically, it would involve installing relatively small turbines at the end of downspouts from rain gutters, rain would then flow from the rooftops of buildings into these gutters, exiting through the downspouts and turning the turbines along the way.
In order to generate enough energy, such a system would perhaps only work in large buildings, with multiple turbines along the downspout, allowing the flowing water to generate the maximum electricity. Even then, I'm not sure if it would be feasible, the only way to really know would be to build models using different types of turbines and gear combinations.
While doing research for this idea, I did find a YouTuber who attempted something similar to different degrees of success. If he was able to build such a system himself, though, I feel sure that it could be manufactured in a more efficient way if the designs are perfected.
I think for high buildings this might work pretty well. During heavy rains, the water collected from the rooftops of high-rise buildings would make a powerful stream, especially in the part of the tube which is near the bottom of the building. I'm not sure what's the system for collecting rainwater from skyscrapers, but I don't think they have external rain gutters, those probably run through the interior of the building. Many gutter tubes could be joined into one to make one powerful stream and generate electricity through the system installed in the basement.
Hydro generators using water from natural streams can generate substantial amounts of energy to fully power a household. Water stream in the joined single gutter of a skyscraper would resemble a very powerful natural stream. This would, perhaps, still only be sufficient enough to power a single floor of the skyscraper during heavy rainfall, but it's something. The power generated during heavy rainfalls could be stored in batteries and contribute a small percentage to the total energy use of the skyscraper or just its bottom floor.
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Could power turbines be installed in water and sewage pipes?
jnikolaNov 18, 2021
What if we installed turbines in all water and sewage pipes in the household/building?
They would be more efficient than in the rain gutter since the pressure is higher. On the other side, the turbines would turn on only when there is a flow, and that is during the flushing or opening the faucet. Since we use the water a lot, this could be significant, right?
Of course, they should be installed in a way so that they:
do not disturb the flow - placed in a side chamber, next to the main pipe
do not affect the pressure in pipes - allow normal water flow from the faucet
isolated from the solid particles (especially in the sewage systems) by filters
work in both, hot and cold conditions
accumulate energy in one battery or immediately power something
What do you think?
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Shubhankar Kulkarni3 years ago
In addition to what Spook Louw said, filter-separation of solid particles would require a separate assembly with a separate pipe for the solid particles to move out. If the particles get stuck along the way, they may be needed to flush out using additional water, defeating the purpose of the idea.
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Spook Louw3 years ago
I think this is a great variation as it is becoming apparent that there simply wouldn't be enough water in the rain gutters to generate a useful amount of electricity. I also considered placing these kinds of systems in storm drain beneath sidewalks and I actually found quite a bit of research that has gone into that.
The problem with implementing an idea like this on indoor plumbing is, like you mentioned, that it will only work while water is being used. Apart from the fact that it might encourage wasteful use of water, I still don't think it would be enough.
I wonder if a device could be built that reuses the same water over and over to generate electricity?
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Shubhankar Kulkarni3 years ago
Spook Louw Right. Even I was thinking of reusing the water to make the whole energy generation process more sustainable. However, I think an additional powered mechanism is needed to restore the used water (even if the same water is reused). For example, the used water may need to be pumped to a height so that it flows down generating more energy. So the process has two parts - 1) flow of water and generation of energy, and 2) restoration of water for reuse. The only way this process is beneficial is when the second part is a by-product of another system. For example, theoretically, the steam from your cooking could be used as energy to pump the water up to a height. I could not find any household activity that could be combined with this idea and generate sufficient by-product energy to restore the water to a height to generate electricity.
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The droplet-based electricity generators
jnikolaNov 17, 2021
Although you wanted to stick to the conventional turbines powered with rain flowing through the gutter, I checked the droplet-based electricity generators and I think they are magnificent!
In this video, researchers managed to power 100 LED lights with just a few droplets of water. If we count in the amount of rain that falls each year (in my city approximately 128 380 liters) and the correlating number of 5 um water droplets, I think the potential to generate energy is huge. As they mentioned, this kind of material capable of generating electricity from droplets could be used in solar panel coatings, roof tiles, umbrellas, and even rain gutters. Of course, to be used in rain gutters, gutters should be modified to disperse water into small droplets which then fall to large surfaces of energy-generating material and are taken to the drains without water accumulation on the roof. Considering the size and the weight of the water droplets, these droplet-based electricity generators could be constituted of many levels of material and each droplet would fall on many surfaces. That way droplets could be "recycled". All of the above-mentioned things give me a reason to believe that this could be big!
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Spook Louw3 years ago
I agree, the DBE is very interesting, I don't think it shouldn't be worked on, I just meant that I did not think it would be a solution as to how we can use water from our rain gutters specifically to generate energy.
Still, very exciting.
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Creating a closed circuit of water flow to produce energy
Spook LouwNov 18, 2021
Juran Perhaps you could expand on the feasibility of this approach, but imagine you had two large containers, one empty, one full of water. If the one filled with water was raised allowing water to flow into the empty one, through a turbine or a system of turbines, and the process was reversed when the tank had been emptied, would that not allow us to continually generate energy?
The two containers could both be attached to a winch or a jack, and manually raised or lowered (manually, so that the system itself does not use more energy than it can produce). Would you, theoretically, be able to generate a meaningful amount of energy?
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Shubhankar Kulkarni2 years ago
J. Nikola Spook Louw I am adding this contribution here since it has a closed system. This is a reel of an almost self-sustaining hydroelectric power generator that you can make at home. The generator does not require a constant flow of water. It uses two turbines that push water towards each other and the same water helps keep both turbines in motion.
With respect to the current idea, when you have water pouring through the gutter, the turbines will start rotating and the excess water will be drained out. You could attach multiple sich generators one below the other and the same water could generate electricity multiple times. If the system is bigger than the one shown in the reel, you could "kick-start" the first turbine manually, and when sufficient water enters the system, both turbines will be set in motion.
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jnikola3 years ago
Hehe, what you propose here is sort of a "Perpetuum rain gutter energy generator", right? I must say I am finding it hard to imagine the positions of the containers and the water flow. Manual adjustments of heights would not make it a Perpetuumenergy source but would definitely help. Maybe we can jump in with some solar power here or a creative "switch".
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Spook Louw3 years ago
Juran I'm not much of an illustrator, but this is basically what I had in mind.
Then, when the empty container is full, it would be raised and the now empty container would be lowered, allowing the water to pass through the turbine again, generating more energy.
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Let's calculate the amount of energy we could get from the Youtube solution
jnikolaNov 17, 2021
Introduction
Let's say an average American household spends 10716 kWh annually, 893 kWh per month, 30 kWh per day, 1250 W/hour . If we would like to generate that electricity via solar energy, we would need 25 conventional 250W solar panels working approx. 5 hours a day (see calculations here). It's not a cheap game and we definitely need help and here is where your idea could turn out to be very smart!
The amounts of the rain
Let's put down some numbers. In my city, an average of 917 mm of rain falls every year . If 10 mm means we get 10 liters per every square meter, an average of 917 liters of rain drops on every square meter of my city. For the sake of the calculation, let's say an average 200 m2 house has approx. a 140 m2 of roof . That means the roof can collect 140 m2 x 917 liters = 128 380 liters of rain annually!
The needed power
To generate power of 10716 kWh/year, which an average household spends, we should build a system (in my city!) capable of generating 0.0835 kWh (83.5 Wh) per liter of the rain. That's the amount needed to fully power the household, which is not our primary goal. Let's first see how much can we generate with an existing solutions.
How much can we generate?
I'll use the example of the cool youtube guy you linked in the session description. He dived really deep into solving the issue of rain gutter energy generation.
In the first video, he calculated that he has a flow of 1.87 gallons/min, or around 7 l/min through a single gutter. He calculated it would result in 2 watts of power, if everything is turned to electricity. With power lost along the way and some adjustment to the system (different turbines, siphons and flow controllers), he came from 0.191, up to 0.612 W and ending in 0.819 watts of power in a second. That means that we are generating approximately 50 W/min, or 7 W/liter, right? (correct me if I'm wrong). We are still generating 12 times less power than we need.
How could we enhance the energy generation?
Multiple turbines on different hights. This would probably not work since the highest turbine would generate least energy because of small height difference compared to the roof. The gains would be minimal, especially when we count in the losses due to the water outflow through the prior "leak holes".
Multiple turbines on multiple gutters. Since we calculated the amount of energy per liter, we would not get any extra energy if we installed more gutters with turbines. We would just get it faster. It could be used to instntly charge stronger devices maybe. Instead, with the adjustment of a youtube guy to control the flow of the rain via syphon, we could do a roof redesign and use it as a rain accumulation pond and deliver stable energy even through times with no rain.
Enhance the turbines. I don't have any bold ideas, since the guy did an amazing job in trying to enhance the energy generation from the rain by changing the turbine system, the propellers, etc.
What do you think about my calculations and sustainability of the system?
Do you have more examples on how to enhance the energy generation?
This is such a thorough response, thank you. The guy in the video impressed me with how well he addressed every issue, that said, I don't think he optimized the moving parts yet. The style of the turbine was only briefly considered (He also never attempted to make use of something like a crossflow turbine in the gutters themselves, and I think he should've spent more time on the Turgo), and even the one he eventually chose was not produced as well as it could have been.
The same goes for the gutter system, making the gutters deeper and narrower might also have a significant effect on the amount of power that can be generated.
Another factor that might have a big effect would be the location, looking at the countries with the top thirty highest average rainfalls per year, they receive almost three times as much as the global average, perhaps such a system would be more effective in these areas.
While I agree with your calculations, I think having multiple turbines at different heights could be effective, depending on the size of the building and the height of the turbines.
Still, I just don't think it's enough water to generate any notable energy, perhaps if multiple houses could share a rain gutter system, we could start getting closer to anything worthwhile.
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jnikola3 years ago
Spook Louw I agree with everything you said. Maybe on higher buildings, the rain gutter could be high enough to have multiple turbines. The location definitely plays an important role, the same as in solar systems.
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Convert one source of water into multiple
Shubhankar KulkarniDec 28, 2021
Inspired by this video, a mini hydroelectric 2-turbine system could be installed to generate electricity from the rain gutters. The turbine converts the single flow channel into multiple smaller channels and each of them introduces water in the turbine improving the motion of the turbine by using a lesser amount of water.
Even then, you need a reservoir. If a reservoir is not possible, electricity generation will be intermittent, only when water flows through the system. The turbine system can be connected to a battery and the electricity could be used whenever needed.
Spook Louw Nov 17, 2021
