Gravitation water vortex power plant | Hacker News Reader

Gravitation water vortex power plant

en.wikipedia.org

227 pointshliyan80 comments

Microhydroelectric has come up on HN before: https://news.ycombinator.com/item?id=6895582

This open design looks interesting, but there are a couple oddities in the Wikipedia article I'd appreciate clarification on from a subject matter expert:

>It was first patented by Greek-Australian Lawyer & Inventor Paul Kouris in 1996[1], who was searching for a way to harness the power inherent in a vortex.

What power is inherent in a vortex apart from gravitational potential energy being converted to kinetic energy?

>after a year of use its operation cost was approximately one US dollar per Watt capacity of output.

Shouldn't that be installation cost, not operating cost?

Fluid dynamicist here. Your understanding is correct. I would not read anything into vague statements like "the power inherent in a vortex". That explanation is basically woo. There's nothing special about vortices. The large vortex used here is sustained by the gravitational potential energy, as you said.

The Wikipedia article read a bit like an advertisement to me.

I don't suspect the Coriolis force of the Earth contributes much to this turbine either, though I admit I don't know much about the Coriolis force in fluid dynamics. For objects of the size shown, Coriolis forces are neglected in my experience.

Edit: Wikipedia backs me up on the Coriolis force being negligible. Aside from starting the rotation in the cited tests (something needs to break the symmetry), the Coriolis force is negligible compared against gravity. In the turbine case I believe turbulence would break the symmetry (the turbulence itself being influenced by imperfections in the flow, surfaces, vibrations, etc.).

https://en.wikipedia.org/wiki/Coriolis_force#Draining_in_bat...

The webpage for one of the companies cited in the Wikipedia article spends a lot of time talking about how their generators are powered not just by gravity but also by the earth's rotation.

My first thought was that didn't sound right so it must just be marketing bs.

Straight up lies.

Couldn't it be simple ignorance? And not intentional deceit?

You're saying the company that built the generators wouldn't know how they work? I don't see how it could be anything else other than intentional.

>"You're saying... Nope, I "asked" a hypothetical question based on this:

>...one of the companies cited in the Wikipedia article..."

And then this:

>liars

If the company in question are saying stuff like "powered by the coriolis effect" then to call them liars, you'd have to actually look at their site and see if they actual sell anything real. Then either do research on the claim, and then come to a judgement, like this:

1. If they are crackpots in their garage and sell hand-made junk from PVC scraps, then yes, it could be ignorance.

2. If they have a real engineer and a marketing department, then it's probably lying.

Which is it? I don't care to look at every site on Wikipedia to figure out which one the comment was about. So instead, I asked the question, maybe someone else has done some research?

Conservation of angular momentum says you can't get energy from the Earth's rotation unless you have a reaction force on something in space.

Indeed. Coriolis force doesn't give any energy since it applies the force perpendicular to the direction of motion.

The symmetry is broken by the direction of the inlet. Point the inlet the other way, the vortex will form in the other direction. Even if you started the vortex the wrong way, the incoming stream would stop and reverse it in short order.

Coriolis Force is meaningless on this length scale.

Still, that doesn’t mean it has to be an ad, it could just be run of the mill arrogance, or the writer drank the Kool Aid. It is funny though, like someone worried about the influence of the cosmological constant on their own body or something.

Would it be viable to create a vortex system that acts as a fluid flywheel?

Yes but centrifugal forces on the simle “rotating fluid” equivalent are too strong and require a costly casing when compared to an equivalent solid flywheel. What they do is they use the rotating part as a pump to push the fluid up a vertical pressurized storage and the pressure there plus the potential energy of the fluid store the energy in a more manageable matter than having it all in the fluid speed

There's a cult of "vortex power" enthusiasts. It's as much bunk as TimeCube, but less obviously disordered.

Ignoring the BS about coriolis, I think there is something legit here.

Of course there isn't any power to be gained from the vortex. What you would gain is a lot of RPMs from very little head. It makes the system be high speed and low torque. The dynamos would be higher voltage (lower amperage), the wiring and inverters are cheaper with lower amperage, and the structure doesn't have to be as strong since the torques are lower. It might even automatically safe during floods, since too much water entering it would distrupt the vortex and halt the wheel.

It is more like a clever hydraulic gearbox that potentially makes all the other components less expensive. Or am I completely off base? The water is spinning around faster than it would be flowing out, correct?

This other company[1] built a prototype of a low-cost vortex in Chile, and claims it produces 15Kw consistently with a drop of 2-3m. If true that's fantastic. As suggested in their video, they could could build several of those in a row because they don't need a massive reservoir.

[1]: https://www.youtube.com/watch?v=gY3p2e1-kN4

Actually I think it is the opposite. This is very low speed at 10-20 rpm. A non-vortex hydro plant runs way faster with 1-2 meters of head, some fast enough that a high-pole-count generator can be directly driven.

To me the fun puzzle is to lift part of the water above the source without moving parts. One can easily do that with a mech. pump but how to make it solidstate?

Well, I suppose you mean: with the only moving part being the water itself. A hydraulic ram can move water uphill easily without any external power, electricity, etc., using basically only simple valves. If I could build a hydraulic ram of ice, does that count?

Re: vortex, reminds me of in "Echopraxia" a bunch of monks powered their monastery with a trapped tornado. No idea how feasible that is but it was badass.

https://www.tor.com/2014/07/29/the-colonel-peter-watts/

> >after a year of use its operation cost was approximately one US dollar per Watt capacity of output.

> Shouldn't that be installation cost, not operating cost?

Since the Wikipedia article does not say, we can not be sure. I interpreted that sentence to intend to describe the long term operating costs without consideration of the up-front installation costs (which obviously will inflate the actual long term operational costs if installation costs were amortized over the lifetime of the unit).

I have one of these on my property the previous owner built it. It takes quite a bit of maintenance to keep working properly, every 3-4 days I have to hike up the trail 15 mins to clear debris. If it rains then I have to clear that day. Also it is sorta scary, it's basically a drowning machine a few years ago I had to build a cover for it to keep wildlife from getting trapped. One of the best things I like about it is that it doesn't seem to effect fish any they come and go up and down stream freely.

Usages are comparable to a hydraulic ram (which has been around for a long time). Probably less expensive because of the simplicity. Clever. https://en.wikipedia.org/wiki/Hydraulic_ram

"The hydraulic ram is sometimes used in remote areas, where there is both a source of low-head hydropower and a need for pumping water to a destination higher in elevation than the source."

I wanted to mention hydraulic rams too! I think they're easily one of the most ingenious and clever mechanical devices ever invented. It's too bad they're not practical for large scale systems.

here's a good 2m30s youtube that shows 15kW one in action: https://www.youtube.com/watch?v=gY3p2e1-kN4

its amazing how little there is to it, and how relatively quiet it is.

Interesting, this is a bit different design... it appears water has to "fall through" that turbine, rather than using the "stirring force" per the wikipedia article.

Not really the same at all. The gravitation water vortex power plant is designed in such a way that fish can easily go through in both directions because the turbine is in the upper, not lower portion of the vortex, leaving the drain clear for fish (and a certain extent, debris) to pass through. This is just a turbine installed in the drain. It's really not much different than a traditional hydro plant.

It's pretty cool so see a combination of manufacturing, installation, and operation. For a distributed power grid this might be a clever addition, add some solar, wind and perhaps battery-backed buffer and emergency fuel-powered generator and you might have yourself a pretty reliable self-sustained power source. I imagine out of those, the wind one might need the most maintenance, or if a lot of crap comes down, the solar panels need periodic cleaning. I wonder what maintenance this generator needs, besides the obvious stuff (brushes? lube on contact points? bearings?).

Wind is random, the hydroelectric generator could act as battery, drawing current to compensate the lack of wind.

Just for an order of magnitude, even if it’s not the same usage:

- One nuclear core: 700MW - Or 50.000 of those microhydraulic turbines.

Although it'd be pretty cool to have a reactor in the basement..

Well, technically it would be pretty hot...

Ba-dum, tish

I don't think there's any more water power being converted into rotational force ( via the vortex ), then there would be using any number of conventional [water turbine](https://en.wikipedia.org/wiki/Water_turbine) designs, like those used at, for example, the [Hoover Dam](https://en.wikipedia.org/wiki/Hydroelectricity).

Once you remove the inhabitat.com-style magical thinking (coriolis, vortex), the main selling points are being fish-friendly and that all the technological bits are in a single package conveniently accessible above water level.

A couple more interesting things come to mind:

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

https://www.youtube.com/watch?v=mrnul6ixX90

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

Also see: Viktor Schauberger (caution: will take you down quite a rabbit hole).

wow, definitely a rabbit hole! the whole Schauberger family it seems.. interesting stuff, thanks!

In general arrangement, it looks rather like a downsized, simplified Francis turbine.

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

You're right. The main selling point of both turbines is the axial flow: the velocity differences between the water and the blades are the same on every sides of the turbine. The shear forces are low enough to let wildlife pass through unharmed (supposing that it's not heavily torqued by a high electric loads).

This has been around in Switzerland for a while. Sadly, the company running it (the first of its kind here) went bankrupt

https://www.srf.ch/news/regional/aargau-solothurn/wasserwirb...

With such a drop required could you harness a tide to produce power. Like maybe allow the tide to fill San Francisco Bay and harness it when it recedes.

Can someone hint why this is different from the usual stuff like falling water on turbines? Perhaps this is more efficient?

Having just read the linked article, it says smaller scale and that fish can safely get through.

It doesn’t require as much of a vertical difference between the input and output.

This is good for low hydraulic head scenarios(basically, where the water doesn't have that much room to fall). With this system you can install it even if water only falls 2 feet, whereas more traditional turbines might need 6-10 feet

Yeah but that just means there's less power there to begin with, so not really economical or useful.

I don't think that's necessarily true. Couldn't you make up for it on volume? I can picture scenarios where you'd have a lot of water falling a small distance and it would be more convenient to install something like this than to use a site with a lesser amount of water falling a larger distance.

Absolutely. The potential power is _water mass/sec * head height * g_ - more water volume is just as valuable as more head height.

Actually, looking at that calculation, I wonder how much the fact that this turbine doesn't introduce cavitation (bubbles) affects the efficiency. The water would be more dense, which would theoretically improve output... no idea if enough to worry about, though.

Less power sure, but it's still untapped power.

I think that's an over simplified view of it.

You can imagine a world where the efficiency of a more traditional turbine setup (measured in watts/$ including amortized capital and operating cost) scales down badly as hydraulic head decreases, and in fact is scales more poorly than the amount of power available.

What you're left with are scenarios where there's room for you to perform more efficiency than a traditional turbine if you can somehow get different scaling characteristics.

The economic viability becomes even more complex once you start considering things like what type of distribution you're dealing with.

Questions like, is it more efficient overall to have more distributed, but less efficiency generating sources, with reduced distribution costs, or have fewer more efficient generating sources with increased distribution costs.

I'd agree that in more of North America and Western Europe, this probably doesn't make sense. But there's still lots of places where the cost of hooking up to the grid is substantial.

It looks like it provides enough power for a few households even with a fairly small version of it. Could be useful in some places.

With large scale dams there is also huge environmental impacts and displacement of the local population. You have to form a sizeable reservoir lake etc. They also take considerable time to build.

It's essentially the same, just applied to the particular case of smaller height difference and low pressure.

Stupid question time: could this be used in sewage systems or similar to generate energy from us flushing the loo?

Of course, its just harnessing gravity pulling down water to spin a turbine.

There are many cases where energy can be harnessed in daily activities, the biggest issue is the efficiency and cost of doing so. Most plumbing use wouldn't add up to nearly enough energy to offset the construction.

My original question was very nearly: can this be used in guttering? I figured that the non-constant flow would probably make it uneconomical.

Yes, and the maintenance issues of using that waste flow.

It has a more fundamental problem because there's just not that much rain falling on most roofs outside of places with monsoon seasons. Because of this even with cheap efficient energy storage there's just not very much there to harvest.

Technically yes. But there just isn't enough potential energy in the water falling on a typical house.

For example, US average yearly rainfall of 76cm, on a 10m*15m roof, at height of two stories at 5 meters, would give you 1.5kWh of energy per year. That's enough to run the appliances in your home for an hour.

You might be in a more rainy location, or have a larger home, but the end result is still insignificantly small.

The energy in the flush is used to push the sewage down the pipe. Take that momentum away and things start to clog.

my first newb reaction: good luck maintaining the turbine :)

my second reaction: on tall building there might be enough height difference to actually bother thinking about it.

Sounds like regenerative braking... not that hard to maintain if installed properly, either - the only sewage exposed part should be the blades?

I don't know, water, shit, toilet paper .. not something I would like a turbine in.

Yeah, I think if you're going to try to recover power from sewer water at all, it's probably best to do it downstream of the treatment.

It will usually be grey water only, without solid waste.

So water from showers and sinks, not from toilets. The only contaminant should be a small amount of soap and maybe a few hairs.

I remember reading an article a while ago about this being done in high-rise hotels. Could not find my original sources, but a quick google found this article: http://bigthink.com/design-for-good/hydro-power-turning-toil...

Back in '95 or so I saw someone who used an old turbo (well, half a turbo) to the same effect during a field trip in one of my "appropriate engineering" classes. I guess it was (is?) enough of a thing they figured out the formulas to size the turbo vs the water head &etc.

Much smaller scale but along with a little solar and a little wind they were 100% off the grid.

I'm dumb as a post, I can't understand why some fancy vortex thing will get you more power than an ordinary water wheel.

A well designed waterwheel could be pretty efficient in these cases, too. Waterwheels tend to lose out when hydraulic head (water drop distance) is too big to construct a practical wheel.

As other people have said, the advantage here seems to be that you get a high rotation speed out of a low hydraulic head. A waterwheel in this case would have lower RPMs, and so require more gearing etc. to be efficient for power production.

In general, turbines are preferred because the moving parts are smaller - rather than having a massive spinning wheel, you just let gravity provide the water pressure, and have a much smaller turbine blade do the spinning.

A water wheel can not have more than 75% of the blades in contact with water at any point (or it would slow it down) and it is rarely practical to have more than 30% of the blades in contact with water.

A turbine in a vortex has 100% water-blade contact all the time, which means it can transfer more power with a smaller size and cheaper materials.

And you can use it as a washing machine https://www.youtube.com/watch?v=akJ9Zo5hhM8

Seem cheaper and less complex + maintenance with solar.

But with solar you only have maybe 10 hours of generation per day at best, so you need to store the energy ( which has inefficiencies) or a grid that can cover many timezones. Using stored water for potential energy means it can be turned on and used as needed, and rated for an average use. In Australia there are plans for more stored energy systems using pumps and generators, probably fed by solar and wind.

Stored hydro isn't the realm of vortex turbines because they cannot be reversed, and because they excel at high volume/low drop. Pumped storage prefers high drop/low volume because losses from evaporation and seepage don't scale with height.

Vortex turbines are for tapping a creek or the canals left behind by a pre-steam ways mill that would otherwise be uneconomical to harvest, or where ecological impact of other installations would be too high.

We used to make these in our above ground pool when I was a kid by running in circles.

73% sounds really efficient. How does it compare to other power plants?

Large hydroelectric plants can apparently have efficiencies of over 90%[1]. Smaller ones somewhere between 80% and 90%.

[1] http://www.mpoweruk.com/energy_efficiency.htm#comparison

Shoot never mind then. Perhaps the appeal here is how efficient they can be while also being small scale.

This is so weird, I had a dream 2 nights ago of this very thing, a steady state hydrocyclone that had a steady state net power output and clean water!!

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