For economic reasons, not every lake with a dam can support a hydroelectric power plant. Some rivers or creeks are dammed for flood control or simply for recreation, and don’t have the flow rate or aren’t deep enough to make the investment of a grid-scale generation facility worthwhile. But for those of us with a few spare parts around and access to a small lake, sometimes it’s possible to generate a usable amount of energy with just a bit of effort.
[Beyond the Tint] is building this mostly as a proof-of-concept, starting with a 1,000W hub motor from an e-bike that’s been removed from its wheel. A 3D-printed waterwheel attachment is installed in its place, and the fixed shaft is attached to a homemade ladder-looking mechanism that allows the entire generator to be lowered into the flow of a moving body of water, in this case, a small stream. A bridge rectifier converts the AC from the hub motor (now a generator) into DC, and after a few measurements and trials, [Beyond the Tint] produced over 30W with the first prototype.
A second prototype was made with feedback from the first video he produced, this time with an enclosed paddlewheel. This didn’t appear to make much difference at first, but a more refined impeller may make a difference in future prototypes. Small-scale hydropower is a fairly popular challenge to tackle, especially in the off-grid community. With access to even a small flowing stream and enough elevation change, it’s possible to build something like this generator out of parts from an old washing machine.
Great project but cant help wondering how long before water gets into the hub?
Agree. Few weeks. But hey, we all have to learn some somehow and mother nature is a good teacher.
It will run flooded because its a brushless motor.
However the bearings might not like the water.
More importantly how long until the local department of ecology fines idiots for daming streams trying to be “green”.
Nobody is even going to notice the amount of water diverted to run a tiny wheel like this, nor the tiny dam you’d perhaps need/want – great you created a duckpond…
A dam really isn’t going to harm the local ecology when done on these sort of scales, you flood or maybe just make boggy a small patch of ground and make practically no change to the path, volume of flow etc of the river – any difference you have made is going to be lost in the noise of natural variation. If anything that tiny patch of permanently wetter probably helps the local ecology as far to many of our rivers are highly engineered and flow too darn fast keeping the local area drained rather more than nature intended.
Numerous small dams have tremendous effects on river ecosystems. They change everything from how fish migrate to how much silt is carried downstream, what types of algae or insects live in the river etc. Fish may get up one dam, but when there’s 20-30 more up the stream, the proportion that gets through to the breeding grounds becomes smaller and smaller, and the variety of fish and other organisms that live in the river becomes less. Biodiversity suffers.
The flooded areas behind the dams also cause troubles because river flows change, so these areas become not permanently bogged but areas where the water levels change from year to year, causing sedimentation of biological matter that starts to rot, which deprives the water of oxygen and releases methane and nutrients downstream, leading to algae blooms and fish die-offs etc.
Lately there’s been more and more focus on tearing down all the unused old mill dams that dot all the small river branches across different countries. They’re restoring the rapids and seeing an marked improvement in water quality and the number of fish species that travel further up the river etc. It has a human impact as well: with cleaner river waters, cities can start picking up drinking water off the rivers and lakes with less filtration and purification, reducing the drain on dwindling deep ground water resources.
So what is your message to the beavers?
At the scales we are talking about here with a flow and head that is so low you won’t bother the fish at all even when blocking the stream entirely – no different to the natural obstructions they have to deal with really (as for it to be worth blocking the watercourse entirely for a project of this scale the water flow at this point would have to be really really darn low trickle of a stream…
The carrying of silt you have me on though, at least a bit. And if your not using and maintaining your mill pond as you are not using it for 100 years or so is a very different thing to a small (and in this case absolutely tiny) diversion of water for a smaller generator you actively using and maintaining, with deliberate control of the water etc. Abandoned anything tends to be problematic, and abandoned or little used water ways will get fly tipped to buggery, often with toxic crap that costs to dispose of properly… Humans are terrible creatures.
Also do note while I wasn’t clear enough I was meaning an artificial side flow and dam not actually planning a dam capable of cutting the river off entirely – as for the scale we are talking about here a small side flow is all you’d want – no individual ‘idiot’ to quote the OP is going to actually dam a river deeper than an inch or two, or find it worth the effort to try with a larger river – a small diversion of flow is much easier.
Yea, they scrapped old mill dams and noticed a sharp decrease of frog population upstream. On closer inspection they noticed the Northern pikes, eating almost all of the tadpoles who were formerly somewhat protected by the old mill. Salmon and trouts had no problem passing, but they didn’t eat the tadpoles.
If you happen to be near https://www.muehle-schreufa.de/ ask the people there, they can talk for hours about which and how many fishes were there, and what happened when they scrapped most small mills in the wider area (spoiler: many old trees next to the river died from now heavily volatile water levels and tipped over when minor floods took away the soil around their roots), and what happened when they built the Edertalsperre (spoiler: the salmon disappeared, until then it was more than plentiful despite all the small mills on the way).
Nothing, since they don’t understand speech. Where beavers build dams, similar issues arise – make no mistake.
Of course your mileage may vary and some river systems would have greater bio-diversity by adding a few carefully placed obstacles, but there’s another issue with abandoned or poorly constructed dams and it’s that they eventually break when subjected to heavy floods, which causes catastrophic floods downstream that roll over human settlements.
As for the “small diversion” hydropower plants; the old mill dams were commonly built to span the entire width of the channel and create a step of a few feet exactly to maintain water level regardless of flow. When the river runs low, a small diversion would be starved of water, but when the water has to pass over the step, you can control how much you’ll divert and how much passes over the dam. When there’s less water available, practically all of it goes through the mill gate and the river is cut off by a wall. When the mill is abandoned, the gate becomes a pinch-point with high flow where only the biggest fish can swim upstream and for the rest it’s a one-way valve.
The Jim-Bob Hillbilly building their own generator in the middle of nowhere is also likely to do this, because they want power all the time and not just when it has rained heavily. They’ll take their tractor and tip boulders and rocks in a line all the way across the channel to create a step that then forces the river to flow through their turbine even when the water is low. Their makeshift dam then collects all sorts of junk and builds up into a blockage, then collapses in the next big rain and sends a wall of water downstream.
Dams do two things: they maintain the water level at the dam, and they create a flood plain upstream behind the dam that changes in size depending on how much the river flows and how high the dam is. The flood plain turns into a marshy area that doesn’t stay wet all the time, so it grows the typical plants but instead of building up and pickling down like a peat bog, it rots and releases humus into the water the next time the water levels rise. This muddies up the river downstream with the contribution of dozens of these small dams at the upper branches.
When you remove the dam, the water levels where the dam used to be become more volatile, but it stops flooding the plains upstream. The area where the dam used to be turns back into rapids – since that’s where the mills were usually built – as the river carves a new channel. Hope you didn’t build your house there expecting the dam to be around forever.
the highly controlled diverting trenches were a precious habitat for all kinds of small water critter, some are now (poorly) maintained out of environmental fonds, but keeping (the energy part of) the mill alive would have been way better in almost every aspect
Both is plain wrong (at least in germany). The rules for water keeping date back hundreds of years, and most of the time it was not for environmental reasons, but because there were other people needing the water, too. The only blocking gates were towards the mill, maintainance had to be done during times with very low water. Sometimes there were flood gates to bypass the weir, but these are never pinch-points for any fish, since they had to be wide enough to carry multiple times the regular water flow to be effective for their purpose.
The hillbilly dams don’t keep enough water to produce a noticeable wave when breaking during a flood. Calculate the volume behind the dam and relate it to the water flow in a flood that is big enough to cause trouble (besides they are not allowed here[tm] because of the water level rise upwards and its consequences, see the old rules and the fights over them among the people using the water).
And, it’s not like the flood plain has to appear right next to the dam either. I think Steve Mould had the video about water mazes where he demonstrates the effect… anyways, in a free running channel, if you raise the water level at the exit by a foot, the water level at the entry lifts by a foot as well – regardless of the fact that the entry may be several feet higher than the exit. Intuitively we’d think that the effect of the dam is only local – that the water simply “drops” into the pool behind the dam – but this is not the case. The water doesn’t “know” how to level off flat right before your dam – it’s going to create a smooth gradient all the way up the river.
That’s because in a dynamic flow, the “pressure” of the obstruction travels upstream along the gradient of the flow and the water level upstream has to rise to counteract that resistance to flow. That is to say, when the river flows at a steady rate and the channel is mostly full, the elevation of your dam can be felt miles upstream where the water rises higher up the banks – potentially over the banks. That’s why the flooding caused by your dam can appear in unexpected places that have seemingly no connection to you.
That depends entirely on where in the river they’re placed. If you raise the level of a small lake upstream by a foot, by accident, you’re going to release a lot of water when your dam breaks.
The flood plain can’t pass a hydraulic jump. If the landscape is so flat a dam generates an extended muddy area or the flood plain reaches more than several
hundred meters up the river there is usually not enough height to operate a mill. However, you have to take the flood plain into account when designing the trench to the mill (which has to be reasonably flat).
You can’t stop a river. It will always find a way over or around your dam.
The point is that a weir becomes a blocking dam when the river doesn’t flow enough to pass over it. Are you saying your mills don’t have weirs? How do they even collect water?
It can when the river flows enough that the hydraulic jump goes away – e.g. rapids become full of water during heavy rains.
Any time you add an obstruction to the river – a dam, a weir, a re-routed bend etc. – it adds resistance to flow. But just as well, you can “fix” a river to flow too much, which causes flooding problems downstream because it flows entirely too well. People have made this mistake as well.
There’s also the argument that during droughts, weirs become fish traps because they form pools of water where fish can linger until there’s not enough water to swim over the weir. The silted pools behind the weirs then become death traps because of oxygen starvation.
… you will get in trouble really fast, unless you got an allowance first
See the contradiction here?
(It doesn’t make sense to lower the water level below the top of the weir, because that costs you the height = energy and possibly the allowance for your mill and gains you nothing: you won’t get more water by doing so. When there is not enough water for the minimum discharge over the weir — which is commonly part of the allowance — you have to shut down the mill, as you would probably do anyway, because there is no energy to gain)
In this case your mill is already flooded. If the water can still flow away, rapids become just more rapid. In a rapid river the flood plane ends at the exact point where the hydraulic jump occurs (which is usually not far away from the weir).
and without the weir the fish would be already dead before, because there is not enough water to swim upstream, but in case of a weir the fish gains the ability to survive for several more days, and people do actually have an option to rescue fish instead of just picking up dead fish from the ground in the dry river
WTF is the “department of ecology”? Did you just make something up to be mad about nothing? Typical Internet-brained jackass lol
Well if he got it out of an actual E-Bike maybe he could use the chain to keep the hub out of the water?
yes, but the chain doesn’t like water and the water doesn’t like chain oil
We can use another wheel to touch the “Hydro” and use those gears to rotate the motor. Yes we will need some chain to connect the both wheels.
The motor can do about 2kW at 800 rpm. He is doing about 100-150 rpm. A faster spinning turbine can improve his results a lot. I estimate that his stream has about 700 W of energy. Extracting about 50% of that should be possible.
“can do about 2 kW” means it produces 2 kW of mechanical power, or actually requires 2 kW of electrical power? Because at peak power an electric motor is not very efficient: you can expect half the input electrical power to end up on the output shaft.
And I’m pretty sure you meant to say “700 W of power“, because saying “700 W of energy” is nonsense.
Its a brushless motor so about 95% efficient both as a motor and alternator.
Not even wrong.
A vortex turbine might be a good choice here due to the low height difference.
Might need a different generator due to the lower speed.
But…its fish friendly, and very resilient against floating debris.
Good luck, like this!
As a kid I had a tree fort waaay out in the woods on my grampa’s land. There was a fairly large creek that ran nearby with a small waterfall. My dad and I built a hydro generator and battery storage system, and that was enough to operate the electric elevator we also built to get into the tree fort and of course some lights. The hardest part actually was treking tools and materials that far into the woods. And if we had to cut or drill something that required serious power, we had to trek it back to the house then back to the fort. Lithium batteries and cordless tools weren’t a thing back then, nor were cheap gasoline powered generators.
Serious power? What the heck did you build, since cutting a 2*12 by hand is no problem, did you put in an I beam?
Cutting a tree lengthwise is however quite alot of work, but I’m still not sure it’s worse than carrying a tree…
But I’m mostly just curious, it sounds like a real good time and a badass fort!
It always baffled me that these weren’t on every waterway.
Economics, plus it’s hard to make them fish friendly. Making a water turbine that is low maintenance is the really hard part. If you’re having to send someone out every few months to fix it, that rapidly makes these things not worthwhile. That’s why solar is so popular for small scale power generation – you can’t beat solid state for reliability.
You don’t need much flow to make it work. Small diameter pipe makes it fish friendly, then your problem becomes keeping the intake debris free…trade offs….
It’s a good thing they aren’t. Dams destroy river ecosystems.
Tell that to beavers 🦫
Beavers destroy plenty of habitat I assure you.
Beavers create plenty of habitats
Don’t bother, they won’t give a dam.
Yet you like to use the power they produce
Not much point crying over spilled milk if you can’t do anything about it.
Hydropower isn’t really the sustainable option it was sold as, and on the larger scale they are actually quite hazardous, especially the huge dams starting to reach a hundred years of age, getting neglected by governments who don’t want to allocate any funds to maintain them.
Hoover Dam – couldn’t get the environmental or human risk approval if you were to build it today.
That’s only true for really big dams. Small weirs for around 1 .. 10kW are ok for most fishes, and sometimes they limit the big, hungry fishes to the lower side, protecting the smaller water habitants on the upper side. Additionally the weirs can provide survival water pools during droughts. (Sorry for the language, my vocabulary lacks some special words here.)
Big dams have fish ladders and have the ecosystem taken in mind when designed. Joe idiot who just want to boast about charging a lithium ion battery won’t consider it
Dams ALTER the ecosystems.
They do not DESTROY the ecosystems.
I live 60 miles west of Asheville, NC.
My area got the same wind and rain from Hurricane Helene.
We have dams for hydro power, recreation, ag irrigation and flood control.
Their environmentalists blocked a 1966 proposal.
They flooded, we came out unscathed.
Same as how a huge monoculture industrial farm doesn’t technically destroy an ecosystem it replaces – it merely changes it, often irreversibly.
Great to hear that. Anyway you must not be agree, but truth is that the dam can destroy an ecosystem. Aftermath of the building a dam these stupid concrete piles does a change that’s not eco-friendly.
These can be added to navigable rivers in place of weirs that accompany locks with minimal changes to the ecosystem. Archimedes screw turbines allow fish to migrate up and down stream. Often the drop and water-flow are too small to generate enough power to recoup the original investment, better renewable energy sources are often available.
Have you seen the way Turbulent does their micro hydropower systems?
Rather than dams they run a diversion channel to send a portion of the waterways flow through their whirlpool genset then dump the water back in down stream. They have systems from 5-100kw which might not be huge, but their small size allows multiple units to be installed along a waterway for higher output requirements. https://www.renexusgroup.com/wp-content/uploads/2022/01/energy-banner3.jpeg
So, like Niagara Falls. They divert only some of the water during the day to run it through the turbines. When the tourists go to sleep they turn off the lights illuminating the falls, and divert much more, basically turning off the falls at night. Much of that water gets pumped into storage reservoirs to use during the following day.
Not really these arent a throttled drain capable of stealing the entirety of the flow. Theyre much simpler. Smaller scale. Micro Hydro. They say fish can just swim through them, though I imagine thats only true to a certain size. In any case, they are closer to what Garreth implied, systems capable of running on almost any waterway with minimal impact.
https://youtu.be/XiefORPamLU?si=iZhzx0dt2Scbc2QC&t=25
Very cool! Kreosan-esque.
Wasting the energy from the fall with the wheel at the top, the turbines in a dam are at the bottom for a reason. Even that foot or so height is potential energy.
Yea the commenter’s were stupid. It needs to be a tube going down into a impeller. Not a water wheel at the top. Water wheels are just for water moving sideways. Water falling has much more energy.
May be a good idea for keeping this rather fragile small wheel intact, and making darn sure the water only ever hits on the correct side – lower the wheel and at greater flow rate the water can be hitting both sides or even only the wrong the side of the wheel if it is dropped down…
Also no point in dumping more energy onto the wheel if it can’t actually use it. So yes you are correct extracting as much of the energy from drop distance would in theory produce more, but in practice…
They are close. Need different propeller for a hub moter. And a big to small water tube for more velocity