Micro Hydro

Micro hydro power systems are the smaller version of large hydro projects like Hoover Dam, but on a residential scale. Here’s a primer on micro hydro.

Micro Hydro

Micro hydro power systems usually generate up to 100 kilowatts of electricity. Most of the hydropower systems used by homeowners and small business owners, including farmers and ranchers, would qualify as micro hydro power systems. In fact, a 10-kilowatt micro hydro power system generally can provide enough power for a large home, a small resort, or a hobby farm.

Micro Hydro power systems use the energy in flowing water to produce electricity or mechanical energy. Although there are several ways to harness the moving water to produce energy, run-of-the-river systems, which do not require large storage reservoirs, are often used for micro hydro power systems.
 
For run-of-the-river micro hydro power systems, a portion of a river's water is diverted to a water conveyance - channel, pipeline, or pressurized pipeline (penstock) - that delivers it to a turbine or waterwheel. The moving water rotates the wheel or turbine, which spins a shaft. The motion of the shaft can be used for mechanical processes, such as pumping water, or it can be used to power an alternator or generator to generate electricity.

A micro hydro power system can be connected to an electric distribution system (grid-connected) or it can stand alone (off-grid).

To build a micro hydro power system, you need access to flowing water on your property. A sufficient quantity of falling water must be available, which means that hilly or mountainous sites are best. Other considerations for a potential micro hydro power site include its power output, economics, permits, and water rights.

To determine if a micro hydro system is feasible, you'll want to determine the amount of power that can be obtained from the flowing water on your site. This involves determining these two things:

• Head—the vertical distance the water falls, and
• Flow—the quantity of water falling.

Once you've calculated the head and flow, then you can use a simple equation to estimate the power output for a system with 53% efficiency, which is representative of most micro hydro power systems.

Simply multiply net head (the vertical distance available after subtracting losses from pipe friction) by flow (use U.S. gallons per minute) divided by 10. That will give you the system's output in watts (W). The equation is net head [(feet) × flow (gpm)]/10.

If you determine from your estimated power output that going micro hydro is feasible, then you can determine whether it economically makes sense. Add up all the estimated costs of developing and maintaining the site over the expected life of your equipment, and divide the amount by the system's capacity in watts. This will tell you how much the system will cost in dollars per watt. Then you can compare that to the cost of utility-provided power or other alternative power sources such as wind and solar power.

Whatever the upfront costs, a hydroelectric system will typically last a long time and, in many cases, maintenance is not expensive. In addition, sometimes there are a variety of financial incentives available on the state, utility, and federal level for investments in renewable energy systems. They include income tax credits, property tax exemptions, state sales tax exemption, loan programs, and special grant programs, among others.

Micro hydro power has a disadvantage over other clean power sources. Unlike solar power, the terrain plays a much bigger part in deciding whether micro hydro power is even an option for you. If it is, you’ll find micro hydro to be both an energy producer and heck of a hobby to play with once it is up and running. Trust me, you’ll always be doodling with it.

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