Generating electricity using household water pressure

C

curt wuollet

The problem, again, is not that it can't be done or won't work. It's that the power that can be generated this way is insignificant in terms of the needs of a modern household or even paying for the equipment, or the water bill for that matter. If it would, nothing would stop people from just running their dynamo from the meter to the drain and making money:^) One ten cent kWh is a lot of power.

Regards
cww
 
Dear Readers,

I am going to generate electricity through ground water and i want the calculation material. how 4cf water discharge of water extracting turbine generate electricity. head of Tube well id 30' and which electricity generating turbine is good for generation.
i am very advance thankful to all reader how give me correct information.

Eng. Jahanzab
 
I would like to recharge small batteries from the water flow for our household usage. Any micro turbines out there?
 

REPLY...

Type in...water powered electricity/rainfall. Top of the page FOR MICRO TURBINE;PLASTIC SPOONS.
 
Dear Friend,

you are right, its costly to generate from water from municipality. But how about using free water flow, the one from sewer or drainage flowing in city. its free and waste, do you think we can use the flow for generating electricity. the flow is not strong enough but I think its present throughout year and endless, I think we can use this resource just like solar or wind, that's useful from waste.

Please advice me on same.

Thanks and regards
 
We have a commercial building with four restaurant, offices etc and probably thirty toilets. The water service is a 2", and I know that the water tower is at least sixty feet above us and one mile away. Pretty impressive head. Seems like we should be able to harness some benefit from a small turbine. (knowing full well it will only generate power when water is being used).
 
C
This keeps coming up and it's worth answering. Not because generating power in this way is practical, but because it shows that people don't understand just how much energy we are using. With that amount of water usage, it's unlikely you would generate enough power to keep the coffee warm, on average. And with the cost of equipment, it would be very expensive power. That's why, even with all the very smart people who want to solve the problem, whether to save the planet, or to make millions, we still have the problem. The amount of energy we use is almost beyond human comprehension with our current lifestyle. That's why all the success stories you see about self sufficiency involve very drastic reductions in energy use, to the point that small scale green generation can provide enough. I've pondered this a lot lately, as just staying alive in Minnesota takes a vast amount of energy the way we are doing it. 9 cords of wood or 9 tons of corn or a couple _thousand_ gallons of propane or oil just to keep from freezing to death. I wish there was a simple answer, but I've got to go and pick trees for cutting when the weather cools. The key statement is probably "The way we are doing it" The whole breakdown is when you suggest to people that they change that. They are not interested.

Regards
cww
 
B
Conservation of energy - 1 m^3 of water falling through a pressure drop of 1 Pa will give 1 J of energy.

In more convenient units - 1 litre through 1 kPa = 1 J

You have 60 feet = approx 2 bar pressure drop = 200 kPa

1 litre through 200 kPa = 200 J

At a flow rate of 1 litre/second, the total power available from your water tower is 200 W.

Neglecting losses.

The water supply people use energy to put the water into the tower - it is highly unlikely that there is going to be a lot of unnecessary extra energy added so you can get it for "free". Now, if you had a water collection point at the top of a hill and had to throttle it to make use of it at a reasonable pressure at the bottom, that's a different story.

Bruce.
 
I believe that most of that energy represented in that head is lost as friction in the delivery pipes. One way of looking at this is if you turned the flow on full and directed it straight up, how high would it go? In most cases, not very high. You're thinking of how much excess energy you could extract from the water. The water utility looks at that as wasted energy (and extra expense). There really isn't that much excess to extract. If there were, the water utility would be installing turbines in their own water mains.

It would take a very substantial flow of water to produce a significant amount of energy. What you should be looking at is how to consume *less* energy by eliminating waste. The savings there can be substantial. That is a much more fruitful avenue than trying to generate trivial amounts of electricity.
 
N

Norman Elliott

A simple way to find out your water flow is to make a temporary dam in the stream with a V notch in it. Measure a known distance, say 1 yard, back upstream from it. Drop a piece of wood (or something else which floats) in at this point. Time how long it takes to cover the 1 yard. Measure how high up the V notch the water is from the bottom of the V and how wide it is at that point. The flow of water is worked out from these measurements.
 
L

Laurin Dykstra

Robert,

We may assume too much. In a mobile home park, water is generally included in the rent. (I am a manager of one) That being said, if a resident left their water on continually, then we could take your number multiplied by 24. 3.29 = 78.96 then multiply it by 3 faucets =$ 236.88/ year. I am a manager, I have the park pressure set at 48psi, and there is way more gph than needed. I have a feeling the 3.29/month is quite low.
 
P

philip scafordi

I would like to know, if a house used the water that went down its drains in a year, to turn a generator...how much electricity would it produce? enough to power the house?? thanks for your time..
 
It is suggested that you refer to wikipedia.org or use your favorite Internet search engine to learn the concept of head and its relationship to power generation.

Once that water exits the faucet, it has essentially zero head, unless you have a large storage area that is located hundreds or thousands of feet about the water wheel connected to the generator.

And if you were to use the pressure of the water entering the building to drive water wheel or small hydro turbine connected to a generator, you would again have essentially zero head, which would make for an interesting shower experience.

As the eloquent and esteemed contributor Phil Corso said in the first reply to this post, there isn't much to be had in this household water pressure idea. Either on the incoming side or the outgoing side.
 
hi there

i have been obsessed to get energy from mains water for ages. had a breakthrough lately :) instead of using the flow i used just the pressure in the system with a relief valve. this works on the principle of a 2 stroke engine. i managed to get a small bike generator running 24/7 without water wastage. the only physics law i am breaking is that = i get free energy yes but it is coming from the mains pump run by the water suppliers:) so it only free energy for me. well i have many gadgets at home eg connected to the tv cable and telephone line. in all i get 5 amps 12 24/ 7 free. enough to run a pc, tv and a refrigerator in winter. see ya
 
R
ray,

You cannot extract energy from water pressure unless you let that water flow. You can use a relief valve to reduce the flow, and that will reduce the maximum energy that you could extract. If you reduce the flow to zero, then the energy you get from it is zero.

If you extract energy from water that you would use anyway, then you are reducing the effective pressure available at the point of use. Your showers would not have as much zing! Your washing machine would take longer to fill. If you can put up with all that inconvenience, then you are welcome to the little bit of energy you would be generating. And if everybody could put up with that inconvenience, then the municipal water suppliers would reduce the pressure at the source and save money for them. There is no free lunch.
 
Hello there,

I live in Brazil, and in here every house and building has it's own "water tower"(common houses have 1 m³ water towers on top of the construction, buildings i don't know :[ )

Most residential buildings have about 15 floors, going from 5 to 10 apartments per floor.

I am a economist (student), not so familiar with physics (and i know it's lame to ask for you to do the math), but could it work?

A common house would generate 60w, right? A building (with a water tower on top) have a greater water column, and more potential energy. If one home would save 3.x dollars per year, a 15 floor, times 5 apartments (75 homes) would save about 215 dollars, and could pay for the system in one year. With some batteries, it could generate power for the elevators, perhaps? Or emergency lights, power up the gate, hallways, i don't know.

Today i live in Copan (it's a 32 floor building, with 1160 apartments, one of the biggest residential complex in the world) and the pressure wastes my wash machine hose every month, so i start to think about using building pressure to generate electricity.

Sorry for my bad english.
 
R
No, Fabio, it will not work. If you read back through the other postings in this thread you will see that whenever the math is done, it shows that it does not work well enough to be cost-effective. Not even close. You are making up numbers (60w? 3 dollars per year). This is just wishful thinking. It is also wishful thinking to say that a system that extracts this energy would cost only $215 and not have on-going maintenance costs.

Here is some math for you. A 32-floor building like you live in, if it is all supplied by one feed of water, would have a difference of about 114 PSI between the top floor and the bottom floor. So if they are getting 30 PSI on the top floor, it would be about 144 PSI on the bottom floor. No wonder your washing machine hoses are failing. Modern construction takes special measures to equalize the pressure on difference floors. Perhaps your building does not have those provisions.

Remember, you can only extract energy from that pressure if you let the water flow. Static water pressure cannot deliver energy. And if you let the water flow even when you are not using it, then you will have to pay more for the water. (Or someone will have to pay.) If you don't have to pay extra for using the water, and if everyone in the building started flowing water to extract energy, then the building management would notice that their water bill is going up. Since you are an economics student, you know what that means. You will no longer get free water. The management will install meters and everyone will have to pay for their extra water usage.

No, if you do the math as an economist, you will see that extracting energy from household water is a losing proposition.
 
I know it's an old quote, but it's yours (i cut some parts so it won't be huge):

"Posted by Robert Scott on 1 September, 2008 - 11:19 am

Relying once again on Phil Corso's analysis posted earlier, a typical 10 gpm flow would generate 90 watts while it is flowing. It is generating zero watts when water is not flowing. And since you are hypothesizing this generator as something that only runs when you would be using water anyway, we must consider how much of a typical day is spent drawing water at the rate of 10 gpm.

Let's leave farming and golf course watering out of the discussion and focus only on residential homes. They consume water when you draw a bath, do the laundry, or wash dishes. I think it would be generous to say that 10 gpm flows for about 1 hour per day. 90 watts one hour per day is 32.85 kw-hr over a one year period. At $0.10 per kw-hr, that produces $3.29 worth of electricity per year. Whatever water turbine/generator you install to capture this power is certainly going to cost you more than $200. With this kind of investment, and getting $3.29 back per year, you will recoup your $200 investment in 61 years. I doubt that any $200 turbine/generator is going to last 61 years without maintenance. So you will never break even, so it was a step backward.

Robert Scott
Real-Time Specialties"

The point is activating the generator by regular use (i imagine that not having a constant flow would waste a lot of potential, but anyway...), and it could specially work on skycrapers. Commercial building usually don't have wash machines and showers, but still have a lot of toilet flushing (6 l/f in here, we don't have those with pump for water saving like US).

It's a thing to add to those barely viable "green buildings", where it would be a medium term profit (1 to 5 years refund is a great investment).

My building was build in the 60's, so i wouldn't even risk to say it has anything modern besides people's furniture. ;)

And that just reminded me, the main hall is like a mall, we have lot's of restaurants/bars and a laundry.

It's not that odd to see constructions like this, a huge building with some stores on the ground floor (though most of them won't have laundries).

As well as US's tv shows (like big bang theory) often shows residential buildings with laundries on the basement, where we could extract most of the pressure with a relatively constant flow, for a short period though, without great impact on the daily use. You know better than me if it's common or not, i went to US once for about 2 weeks (and sure want to go again, and stay a lot more).

My point is not using it to extract from one household water, but a big group of them, in buildings 100+ apartments or 1000+ workers. I know there is a maintenance cost and it's way more than 200 bucks to build the system, but in a larger scale could it work?
 
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