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Basics of an Off Grid Micro Hydro Installation
by Staff Writer

Only a small percentage of parcels are suitable for a micro hydro installation. But if you have an adequate change of elevation and sufficient water flow, micro hydro may be the most efficient and cost effective way to power your homestead.

Micro Hydro Turgo Turbine
turgo turbine micro hydro installation
- photo courtesy of Gary St. Onge
Capturing the energy of moving water is not a new idea; it has been used to mill grain, operate bellows, and manufacture textiles for hundreds of years. It was only recently, however, that we learned to convert the potential energy of moving water into electricity. The construction of dams and modern hydroelectric plants really began in the 1930s. The Grand Coulee Dam in Washington, which was completed in 1942, is capable of producing over 6,800 megawatts of electricity and is still one of the largest producers of electricity in the world. One of the great things about hydroelectric is that it can be generated on any scale, but scalability is only one of the benefits of hydroelectricity.

Smaller installations do not require that a reservoir be built, so there is very little impact to the ecosystem. Power generation tends to be more consistent with micro hydro installations than with solar arrays or wind turbines -- it's hard to guess how much the sun will shine or the wind will blow. Traditionally, micro hydro generation is more efficient than other forms of alternative energy. It's not uncommon to capture 60% -- or more -- of the potential energy stored in moving water. Some people frown on wind energy because they don't care for the whirling noise that turbines may generate, or they don't want an unsightly tower and guy-wires on their property. Micro hydro installations are quiet and low-key. Most people won't know that you are generating electricity unless you point out the components of the system.

Micro Hydro Water Intake
water intake for a micro hydro installation
- photo courtesy Joe Hartvigsen
For a successful micro hydro installation, you need to know the head and water flow of your site. Head is the pressure created by the difference in elevation of the water intake and the turbine. The greater the difference is, the higher the pressure generated will be. Water flow is the amount of movement expressed as gallons per minute. Measuring the head and flow are critical steps when planning your micro hydro installation. If your site has high head but low flow, an impulse turbine would be most efficient. If your site has low head but great flow, then a reaction turbine would be a better choice. Determining the cost and components necessary for a successful installation are impossible until you have accurate head and flow measurements.

The materials, appearance, and cost of micro hydro installations can vary greatly, but they should all share the same basic components: intake, pipeline, turbine, and generator. Water is filtered and funneled into the system through the intake. The water builds pressure as it travels through the pipeline (or penstock) to the turbine. The potential energy in the water is then converted into kinetic energy in the turbine. An alternator or generator uses the kinetic energy to produce electricity. The electricity can then be

stored in batteries, used directly, or fed into the grid. Numerous components can be used to condition and manage the electricity, but this is beyond the scope of this article.

Micro hydro turbines can be a cost-effective way to generate electricity, but only if they are designed and installed correctly. Selecting an improperly-sized turbine or pipeline can severely reduce the efficiency and output of your system. Do-it-yourselfers can still tackle their own installation, but should proceed with caution. Consider working with a consultant or at the very least, talk with your turbine vendor. Turbine vendors know their business and can provide a wealth of information if you take the time to ask.

For more information about turbines and micro hydro installations, visit:
St. Onge Environmental Engineering, PLCC