Get Started with Microhydro Power

Beginner
Turgo runner in an Australian-made Platypus turbine.
Shown from beneath—the 4-inch (10 cm) turgo runner in an Australian-made Platypus turbine.
A two-foot diameter Pelton wheel.
A view into a turbine shows a relatively large (2 feet in diameter) Pelton wheel. Peltons vary in size from 3 inches to 13 feet or more, depending on head and flow.
A Power Pal turbine with a Francis runner.
A Power Pal turbine with a Francis runner direct-coupled to the alternator above.
Nautilus turbine showing the Francis runner.
The underside of a low-head, high-flow Nautilus turbine showing the Francis runner, and above it, the innovative nautilus-shaped headrace.
The container fill method of measuring flow.
The container fill method of measuring flow means getting in the stream and timing how long it takes to fill a container of known volume.
Microhydro intake.
Intakes can be as simple as a screened box submerged in the watercourse, or they can involve a complete damming of the stream.
Turgo runner in an Australian-made Platypus turbine.
A two-foot diameter Pelton wheel.
A Power Pal turbine with a Francis runner.
Nautilus turbine showing the Francis runner.
The container fill method of measuring flow.
Microhydro intake.

Get Started with Microhydro Power

After you’ve done your load analysis and know how many kilowatt-hours you want to generate, a microhydro system site survey primarily focuses on four measurements:

  • The flow—how many gallons per minute (or in larger systems, cubic feet per second) are available, and how much water you want to divert from the stream;
  • The head, or vertical drop, between where the water is removed from the stream and where it leaves the turbine runner. Exactly where or how the pipeline runs is not vital for this measurement, though calculations of losses for pipe and fitting friction will need to be made;
  • The pipeline length, which, combined with its diameter, will allow you to price what may be one of the most expensive parts of the system;
  • The length of the transmission wiring, which may also be a significant cost, and must be sized to minimize energy losses, and be well within safety parameters.

For most people, a combination of motives—environmental, independence, reliability, and cost—make hydro-electric systems attractive. The “bottom line” may end up being what the actual cost per kWh is. To arrive at this, you’ll need a complete design along with construction bids or estimates. If it’s a grid-connected system you’re after, you’ll also need to know what your local utility policies are for renewable energy systems, and at what amount you will be credited or paid. You’ll also need to know if any incentives (utility or government) exist. Often, microhydro system incentives are less than those for solar energy systems, and sometimes non-existent. Available incentives, though, may be generous because of hydro’s 24-hour generation capability. Once you have these figures, you’ll need to predict how many years your system will operate and the annual maintenance costs, and then you’ll be able to calculate the cost per kWh.

Throughout your design, consider strategies to get the most out of your precious flowing water resource. Properly sizing the pipe will get the most energy to your turbine, minimizing friction loss. Choosing the right turbine and runner for the job will maximize production for your stream’s specific head and flow. And sizing the wire correctly will keep the system safe, and keep you from losing energy in the transmission of your hydro-electricity.

Get an education about common hydro myths, and avoid scams or schemes that promise more than they deliver. Lean on professionals and others with experience in the field to discover what has worked well to produce hydro-electricity. If you do your homework, and apply what you learn with care, hydro-electricity can provide low-cost, clean energy for many years.

Comments (10)

BobbyBo's picture

Hi. Thanks for your work. I love it.

My situation is related. Off-grid seasonal lakeside cabin used on weekends. I want to use solar panels/wind turbines to generate electricity during the days and weeks when I am not at cabin. The idea would be to store this generated electricity not in a traditional battery, but as potential energy /head in a microhydro set up. In other words run a water pump when solar electricity is available to pump water into a reservoir uphill of the cabin (say 30 feet elevation). Then when I am at the cabin, use this elevated reservoir to drive hydro electric generation for on-demand use. I understand the high losses involved. This is not about being efficient per se, but rather its about creating a storage for energy that trickles in over a period of time to be used later when needed. Any comment? I have rock formations about 30 feet above lake level which would be dammed to make a decent reservoir. Thanks

Ian Woofenden's picture

Hi Bobby,

The losses will indeed be great, which means you'll need much large solar and wind collectors than you'd need otherwise. And the hydro generator will need to be much larger than a system with batteries, to accommodate the peak load. Perhaps an even larger drawback is the size of the reservoir needed. Note that a hydro system's "collector" is measured in square miles -- a watershed. Some math involving your energy need can give you estimates on how many thousands of gallons you'd need to store.

In addition, you are describing the potential of _three_ systems to do what a simple solar-electric system might easily do. A weekend cabin is ideal for a PV/battery system, because it is use sporadically and then has time to recover. Why waste much of that solar energy by putting it through the pumping and hydro generation loop, where every single step is a loss? The losses will greatly exceed the modest and predictable losses in a battery system, and the cost of setting up the pumped storage system will also be large by comparison.

Pumped storage is used by utilities in some places, but only where there is a great surplus of energy, so the losses are not important. What you describe is using precious resources (wind and solar electricity) that you have to pay dearly for in the first place. It's best to use those resources carefully to minimize your upfront cost and maintenance costs. Using solar electricity directly is the most efficient, and battery storage is a close second. Elaborate schemes beyond that won't be better.

See Ben Root's article on hydro myths for more:
http://www.homepower.com/articles/m...

Regards,

Ian Woofenden
Home Power senior editor

BobbyBo's picture

Thanks Ian. Of course I don't expect it to work. But there are some unusual circumstances in my scenario made me wonder whether there was any chance for pumped storage to match battery storage, despite the significant additional losses. 1) frequency of use: if the cabin is only used 10 nights a year yet solar and wind could be harvested for 365 days. I don't think battery storage works well for that kind of duty cycle. 2) temperature: this cabin is in Canada so I dont know whether batteries would enjoy being cold for 6 months of the year. Certainly the water pump/reservoir system would halt during frozen months. 3) usage would be minimal - perhaps LED lighting or whatever load a small hydro system could economically produce in the circumstance. 4) the terrain above the cottage is good for this. The head would be only 30 feet or so, but there are already beaver ponds measured in acres up there with room for more. I would not want to simply drain these ponds, but would want to refresh them or create a new one.

So I understand that pumped storage is not efficient. My interest is solely in finding a way to store solar and wind power accumulated easily over very long periods of time before being used. It could also act as a base load.

Thanks again

Bobby

Ian Woofenden's picture

It sounds like a fun project, Bobby, if you start off assuming it will be expensive and inefficient. ;-) If you don't have a natural hydro resource (not beaver ponds, but continuous water flowing down hill), I've never seen a situation where manufacturing one makes sense. The smaller the load, the less cost-effective such a complicated system will be.

Small PV systems for seasonal/weekend cabins are very common in the great white north. Appropriate charge controller settings can protect batteries. Careful load analysis and system sizing will avoid disappointment. While you can't store summer energy for winter usage, batteries really do a pretty good job storing energy for intermittent usage, and most weekend cabins are used mostly in sunny times of year. I'd suggest you start with a small PV system -- you'll learn a lot about your usage and potential!

Regards,

Ian Wooofenden
Home Power senior editor

backachers's picture

I don`t have a stream but I do have a 30 inch culvert that flows at least 1/3 full ten months of the year. My generator site would be about ten feet below. what I am looking for is a turnkey unit to fit a four to six inch pipe 12 volt to a converter strong enough run a small heater any Ideas thanks

Ian Woofenden's picture

Hi backachers,

You've mentioned half of the hydro equation -- your ten feet of vertical drop (head). Now you need to actually measure the flow, and preferably several times over the year. Then you'll have the information needed to calculate potential power and therefore energy. And you'll also be able to correctly size the pipe and begin to choose a turbine. Without good info on your head and flow, you're rather in the dark.

Any hydro turbine manufacturer worth dealing with should be able to take your head and flow numbers and recommend products in their line that will tap it efficiently. Check out HP advertisers and contact them once you have solid numbers.

And see the variety of other hydro articles in our back issues, including my HP132 article:
http://www.homepower.com/articles/m...

and how to measure head and flow:
http://www.homepower.com/articles/m...

Regards,

Ian Woofenden
Home Power senior editor

Ganderwiz's picture

Everything I have read about micro hydro requires a stream or river to make it work. I was thinking could you build a "closed circuit water volume" micro hydro generating system? What I was thinking of is a large tank say 1000 gallons on a frame say ten feet in the fair and a 2" pipe flowing to a turbine generator and then out of the turbine into a hydraulic ram water pump to lift the water back into the tank after it has left the turbine. Is that even feasible?
Will it eventually stop due to degrading water pressure over time?

Ian Woofenden's picture

Hi Ganderwiz,

It will not work because every energy exchange incurs a loss.

A ram pump needs a great deal more water to operate than it pumps. Efficiencies can be 20% or lower -- this means 80% of the water may be wasted. Best case is around 60% efficient, so you're still losing 40% of the water.

Then you have the inefficiencies of the plumbing (friction loss) and hydro turbine.

Hydro systems work because the energy is free and naturally recurring. Any attempt to manufacture/pump will not be a net gain.

See http://www.homepower.com/articles/m...

Regards,

Ian Woofenden
Home Power senior editor

Ganderwiz's picture

Addendum: the reason I am interested is because I am on dialysis and I do it at home daily (CCPD) and have an electrically operated machine that I am hooked up to for 11 hours every day. The area where I live is considered rural and if the electrical grid goes down, The Co-op told me that though they would keep in mind that medical equipment was in use at our house, they could not guarantee that Our home would be the priority for restoring power. We do not have any running bodies of water on our property, and cannot afford a standby generator system that works off of propane or a complex solar power generating system. That's when I started thinking about hydro and the concept I described came to mind. At first I was toying with the idea of making it out of commonly available items Like car alternators, water pumps and rear ends using them as a PTO from a water wheel to run the alternator for the power generation and the water pump to raise the water back to the reservoir. but the problem with that is I don't know how efficient that setup would be or if it would even work. Then I found this website and the turbine idea began to take shape after I earlier found out about the existence of a hydraulic ram pump that works only off of water pressure alone. If there is no pressure loss when the water leaves the turbine, it seems to me that a hydraulic ram pump would then easily lift the water back up to fill the reservoir.

Ian Woofenden's picture

Again, your concept will not work. In addition to my comments above, a hydro turbine's _job_ is to take all the energy out of the water, leaving it "dead".

It sounds like you need either a backup generator or a battery backup system. Depending on your energy need and the length of outages, you may be able to use a battery bank and inverter/charger without solar input—simply charging from the grid while it is up, for use when the grid is down.

Ian Woofenden
Home Power senior editor

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