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Now that you have determined your available resource and the rough viability of a system, it is vital to select the right equipment for your location. Although waterwheels are still available today, almost all micro-hydropower systems use turbines. Turbines turn when moving water strikes turbine blades, which in turn spin a shaft connected to a generator. There are two primary types of turbines used for micro-hydro systems: impulse and reaction. Impulse and reaction turbines have different designs that make them better suited to either high-head or low-head applications.
Impulse turbines are the most commonly used design for high head systems. This relatively simply design uses the velocity of flowing water to turn a wheel, which is called a runner. The Pelton and Turgo wheel are the most common types of impulse turbines. The photo on the left shows a common Pelton wheel. The Turgo is an upgraded version of the Pelton wheel that operates more efficiently under certain conditions, particularly medium heads (50-150 feet). The Turgo wheel is also often less expensive to manufacture than a Pelton wheel. Generally, impulse turbines can operate under low-flow conditions but require a high head.
Reaction turbines utilize pressure as opposed to velocity to produce energy, and they often have very high efficiencies. Most large-scale hydroelectric projects use reaction turbines, but they can be used in low-head micro-hydro applications. Due to cost, reaction turbines are less commonly utilized than impulse turbines for micro-hydro installations.
In the right location, micro-hydro has the potential to be a low cost source of renewable energy. The unique nature of each individual hydroelectric resource means that it is difficult to provide estimates for the cost of systems. For example, low-head systems are generally more expensive than more common high-head systems. Also, some landowners may already have the civil works, such as a diversion or penstock already installed for other purposes.
Unfortunately, micro-hydroelectric systems are not eligible for many of the same financial incentives as other renewable energy systems. The federal government provides relatively few incentives for micro-hydro, but local utilities and states may have some incentives. In Montana and Wyoming, state incentives can include property tax and/or sales tax exemptions.
Federal incentives as of 2011 include the following:
Davis, Scott. Microhydro: Clean Power from Water. New Society Publishing. Canada: 2003.
Kindberg, Leif. Micro-Hydro Power: A Beginners Guide to Design and Installation. National Sustainable Agriculture Information Service. February 2011. Available at http://attra.ncat.org/attra-pub/farm_energy/hydropower.html.
Northeast Regional Agricultural Engineering Service – University of West Virginia Cooperative Extension Service. Small Hydroelectric Plants. EPP-13.ON: FS 13: 1978. Available at http://www.wvu.edu/~exten/infores/pubs/ageng/epp13.pdf.
United States Department of Energy: Energy Efficiency and Renewable Energy. Small Hydropower Systems. DOE/GO-102001-1173: July 2001.