Energy from gravity fed water lines, bullshit or useful?

[Lukas]

It works if you do not have water metering, or if you are lucky enough to have a property with both a stream that is perennial and which is on a very steep slope so you have a good static head. There was a nice set of articles ( location escapes me ATM but it was in South America) of an off grid house, powered using a local stream that was diverted to drive a pelton wheel and drive a generator to provide power, with the power line loss being reduced by using 2 transformers to up the voltage to 2kV for transmission, and then using standard copper wire in a conduit. He essentially got free power and water, along with heating for his locally built well insulated round house.

http://ludens.cl/paradise/paradise.html

[mtdoc]

http://ludens.cl/paradise/paradise.html

Thanks for the link!  That is an awesome microhydro system.  2.3 - 8 kW output is huge!  You could fly to the moon on that amount of power 

When I put my own very small system in I'll be happy if I get 300 watts out of it consistently during the wet months.  Still, that's 7.2 kWh per day - enough to run our home if needed. My current PV system puts out 10-20 kWh on most non winter days.

[CatalinaWOW]

Just to fan the flames, I will point out that regulatory influences and scope of analysis can change the economics of a particular energy source.

For example, there are quite a few places that still have unmetered water supplies.  Thinking locally, that is a virtually unlimited flow of water at 30-90 psi head.  A household hydraulic motor or turbine dumping water into the sewers could extract energy from this flow with no incremental costs.  From a system view it is dumb.  From an ethics point of view it stinks, it adds to pumping and water production costs for the other users of the system.  But it provides a benefit on an individual basis.

I do suspect that if this was widely or heavily exploited the loophole would disappear rapidly.

[mtdoc]

Just to fan the flames, I will point out that regulatory influences and scope of analysis can change the economics of a particular energy source.

For example, there are quite a few places that still have unmetered water supplies.  Thinking locally, that is a virtually unlimited flow of water at 30-90 psi head.  A household hydraulic motor or turbine dumping water into the sewers could extract energy from this flow with no incremental costs.  From a system view it is dumb.  From an ethics point of view it stinks, it adds to pumping and water production costs for the other users of the system.  But it provides a benefit on an individual basis.

I do suspect that if this was widely or heavily exploited the loophole would disappear rapidly.

"
Good points but..

Just because a water connection is "unmetered"- does not mean it is unmonitored.  Sudden large increases in flow would likely be noticed. That is how systems are monitored for leaks.  I know because I am on the board that manages our small (35 home) state regulated water system. We do not charge by use but monitor use nevertheless to catch leaks.  We have been doing this for many years and now the WA state Department of Ecology mandates water conservation measures including a system for monitoring for leaks.

A typical residential water system with say 60psi (equivalent to 138 ft of head) would use 10 gallons per minute or 14,400 gallons per day ! just to produce a very modest 3.3kWh a day.  If you're on a water system you likely also have grid power - so would it really be worth it to save less than a dollar a day on electricity?


138 ft. × 10 gpm ÷ 10 derate = 138 W × 24 hrs.
= 3,312 Wh per day

[miguelvp]

Use it only for the water spent that doesn't require high pressure? Like filling up the tub for a bath? or the toilet tank?

[cdev]

I have a friend that I have not seen in a long time who lives on a property that has a year round stream and she and her husband have done exactly that, they have a Pelton wheel, which is a wheel made out of cast metal with perhaps a dozen cups to catch a strongly propelled stream of water (coming out of a nozzle) It works as advertised, and last i saw it, they were getting maybe 200 watts out of it. for maintenance, basically it uses nylon stockings to filter the water, so the stockings have to be replaced periodically. And you have to oil it once in a while. They have a 12 volt home, and they run LED lighting, a refrigerator that opens on top (more efficient) a boom box type stereo, a laptop computer..

They have a big pond (maybe 100 x 100 feet) that fills with water in the rainy season (I hope its not dried out now, it probably is..)

It didn't feel like they were roughing it.

I hope they are okay now. California is going through a major drought.

[benbradley]

I hope necroposting isn't too frowned on here, but ...

This is the sort of thing that "keeps on giving," but in the wrong way - the idea is too easily misunderstood, and promoted by well-meaning people all over the Internet. I STILL see this (several "news" articles along with the Youtube video in #21) and similar stories on Lucid Energy (whether using the company's name or not) posted on Facebook, and the comments are NOT about whether gravity feed works to generate electric power (it obviously does, just like hydroelectric dams everywhere), but people DO NOT notice or understand the "gravity feed" part and think it should work in ANY city, regardless of the source of water. It's really the common  interpretation of this thing that's become a scam.

This recent (four months ago) post on Upworthy is arguably part of the problem - it's one of probably many "feel good" places where this sort of thing gets posted online:
https://www.upworthy.com/portland-now-generates-electricity-from-turbines-installed-in-city-water-pipes

The only mention of how it actually works is about eight paragraphs into the story, near the end:

"Fast Company points out that, in order to be cost and energy effective, Portland’s new power generators must be installed in pipes where water flows downhill, without having to be pumped, as the energy necessary to pump the water would negate the subsequent energy gleaned."

There's no mention, stated or implied, of these pumps needing to be gravity fed up to this point. I doubt many of the people who post about this thing understand the concept even if they've read that far.

But wait, there's more - read (if you dare) the Youtube comments!
https://www.youtube.com/watch?time_continue=8&v=Vpubi1GjoBE

[cdev]

just a thought.

Hydro power is likely the least sketchy form of energy there is because its clearly the oldest, its been used by humans in various forms for thousands of years.

Also as somebody who has spent time in the Northwest and Northern California, there are lots of experts on independent power generation methods there because they are widely used. Very widely used. Its not pie in the sky at all, its how people run their appliances. Before PV got big there was small hydro.

People who live off the main roads have small hydro setups wherever they can manage them. You can see the ponds along every creek on Google Earth, almost every one has a small hydro setup.

Its a known quantity.

Likewise, on the East Coast, before there was electricity, industry in the US got its start- Towns sprung up around mills, that had available sources of water power.

The falling water was 'free energy', the kind you can bank on.
As long as there is water in the river.

[CatalinaWOW]

But even this least sketchy form of energy has it's faults.  Hydropower is blamed for the end of several salmon runs and the extinction of dominant fish species in the Colorado river system.  Many hydropower plants are now being decommissioned in attempts to reverse their ecological effects.

TANSTAAFL

[coppice]

But even this least sketchy form of energy has it's faults.  Hydropower is blamed for the end of several salmon runs and the extinction of dominant fish species in the Colorado river system.  Many hydropower plants are now being decommissioned in attempts to reverse their ecological effects.

TANSTAAFL

New schemes usually have arrangements to let wildllife pass through, and to allow annual flushing, so nutrients from upstream can reach downstream farmland. The flushing also avoids the reservoirs silting up, which has been a big problem with a lot of early schemes.

[cdev]

A few years ago they discovered submerged forests of trees on the bottoms of lakes in the high Sierra, since then they've realized that several times in prehistory recent enough for the trees to still be there there have been extended droughts far longer than anything we've seen since the European colonization of the New World.

So, trees grew on the bottoms of where today there are huge lakes. They dated the most recent batch at around 900-1000 years ago using dendrochronology, but there are older trees too.

[SparkyFX]

But even this least sketchy form of energy has it's faults.  Hydropower is blamed for the end of several salmon runs and the extinction of dominant fish species in the Colorado river system.  Many hydropower plants are now being decommissioned in attempts to reverse their ecological effects.

Over here there are several ship locks in the river, they each have a fish ladder because of that.

But back to the hydro power generation:
To accomodate larger loads, there are even Pumped hydroelectric energy storage facilities, which seem to be cost effective just because they buffer high amounts of energy and even out the swings in use or generation. It is a simple calculation if it is reasonable to switch on additional gas turbines or open the valves on the buffers. Can´t be built everywhere, obviously.

Anyway, coupling power generation to the flow of residential water sounds a bit strange, however i would not say there are no cases in which it could be practical - the mentioned examples of excess head and a high continuous flow might use it well. Would be interesting to see how water  and electricity use correlates.

[Circlotron]

Who the hell puts their water reservoir 1000 feet up?

If you had an inactive volcano caldera it might be useful. Especially for hydro power.

[vk6zgo]

Back in the day when quite a few small towns in Oz had piped water but no electricity supply, a device was available to take the place of electric food mixers.
This  device coupled to the water tap (faucet)) & had a small turbine inside, which spun the mixer attachments.
The down sides were that it wasted water, & there was already a device which could do that job-------Mum!

There were "workarounds" for the functions done by various electrical appliances, such as "kerosene" refrigerators & clothes irons which burnt petrol (actually unleaded petrol -- sometimes called "range fuel").

These were quite widely used, unlike the water tap  mxer.