Water Power
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Large scale hydroelectric power has been used worldwide
for a long time to generate huge amounts of power from water stored behind
massive dams. Small scale hydropower has been used for hundreds of
years for manufacturing, including milling grain, sawing logs and manufacturing
cloth. However, it can also be used without a dam to generate
electricity for home scale remote power systems. These so-called
micro-hydro installations can be a very good complement to a solar power
system, as they produce electricity 24 hours a day.
Waterwheels--It's important to differentiate between water wheels
and water turbines. A water wheel is more akin the antique version we are all
familiar with--a massive wooden wheel that slowly turns as the creek pours
down over it. Water wheels spin slowly, but with lots of torque. They are also surprisingly efficient! One very good place to go for waterwheel information, kits and photos is The Waterwheel Factory.
NEW 6/21/2004 ---
Scotty's new homebrew hydro plant, using a Banki Turbine design built from scratch. The generator is a homebuilt permanent magnet alternator, very similar to our Brake disc alternators. In a Banki design, the water hits the vanes twice, once upon entrance and then again upon exit. There is only about 3 feet of head available at the site, and the system is producing about 2 amps at 12VDC, fed by a 4 inch pipe. Check out the page about it HERE.
A while back, one of our neighbors constructed a water
wheel generator using a squirrel cage fan, belt, pulley and surplus tape drive motor that produced a steady 1-2 amps of power, 24 hours a day.
He used a natural dam (a log that fell across the creek years ago) to get
the fall and to mount the generator on. Click here for more information on this clever water wheel.
Some General Micro Hydro Power Information
NOTE -- as you can see from the photos and web pages linked to above, we don't have much of a hydro power resource here. The crick is very small, often dries up in the summer, and freezes nearly solid in the winter. So we are not the best place to direct your hydro power questions to, we have hardly any hydro experience. There are some great sites listed in our Hydro Power Links section.
Turbines--All of the commercial micro hydro generators available
today use a small turbine connected to an electrical generator or alternator.
Water is collected in an intake pipe upstream, travels down to the turbine
in plastic pipe, and is forced through one or more nozzles by its
own gravity pressure. No dam is needed; systems without a dam are
called "run of river" systems. Power is generated
by a generator or alternator directly connected to the turbine wheel (no
gears or pulleys needed). All of the factors below must be calculated
correctly for your micro-hydro equipment to make power most efficiently.
All commercial micro-hydro setups are custom-made by the manufacturer for
your specific application. For proper operation, you must supply
the manufacturer with specific data about your site, most importantly the
vertical drop in feet (called "head"), the amount of water flow available
during different seasons in gallons per minute, and the length of pipeline
required to get a sufficient head.
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In general, for a water turbine you need at least 3 feet of fall and at
least 20 gallons per minute of flow. If you have more fall (head),
less water is required. You can calculate potential head with a water
level, a contractor's level and stadia rod, or with just a string level
attached to a measuring stick. The more fall and flow that you have,
the more potential power you can generate. You can measure flow by
building a weir in the creek and measuring how fast it will fill up a 5
gallon bucket.
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Your pipeline must be of a big enough diameter to minimize friction loss
in the pipe. Your micro-hydro supplier can give you specific information
regarding this.
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Nozzle size and turbine wheel type are all interrelated to your total head
and flow. Again, your hydro supplier will customize these for your
specific application. Often, different size nozzles are designed
to be switched in and out as stream conditions change throughout the year.
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There are two main types of turbines, impulse and reaction. With
impulse turbines, a jet of water is created by the nozzle and squirted
onto the wheel. Reaction turbines are more akin to propellor that
spins INSIDE the pipe, generating power.
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The 3 primary impulse turbine wheel types are Pelton, Turgo, and Cross-flow.
Pelton wheels are used in low flow, high head conditions, and Cross-flow
wheels are for high flow, low head installations. Turgo wheels are
somewhere in the middle. Francis and propellor turbines are the most
common reaction type; the Francis design is very similar to the innards
of a centrifugal pump. A Kaplan turbine is also similar to this design.
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Home built reaction turbines have been built using centrifugal pumps running
in reverse (generating power with moving water instead of using power to
move the water). We hope to have more information about experimenting
with this soon. You can buy a book about from ITDG books, they also have a book about using induction motors as generators for micro hydro power.
| Books - Wind, Solar, Hydro, Biofuels, Geothermal, Science, and more. If we haven't read it, we won't sell it! |
Hands-on Workshops - Get your hands dirty learning renewable energy. Fully accredited by ISPQ, IREC and NABCEP. |
| Wind Turbine Parts and Kits - Everything you need to build your own. Buy your parts ala carte, fabricated in our off-grid shop. |
Balance of System - Important things you need, but can't find. Turbine diversion load systems, disconnects, and more, with expert advice. |
| Data Acquisition - Keep track of the energy you make and the energy you use, and the system that's producing it. |
Consulting - We work with clients to design clean energy solutions for remote, off-grid areas worldwide. |
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This page last updated 6/21/2004
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