Different Styles of Turbines

Impulse Hydro Turbines

• Impulse turbines represent one of two main types of micro hydro turbine systems. Impulse turbines use the water's speed to move the turbine's wheel through a series of buckets or tabs on the runner. According to the U.S. Department of Energy, impulse turbines are "suitable for high head, low flow" sites and applications. Pelton impulse designs use a wheel suspended in an aerated space with one or more jets discharging water over the turbine's wheel. Cross-flow impulse turbines use a squirrel cage blower design, which allows water to pass twice through the cylindrically shaped runner and can be used on larger flows and lower heads than the Pelton design.

Reaction Hydro Turbines

• Reaction hydro turbines use the combined forces of pressure variances along with moving water to generate electricity. Reaction turbines use direct placement over the water flow and are used for sites with lower head and higher flows than impulse turbines. Propeller reaction turbines use constant contact with the water to provide constant pressure to power the turbine. Kinetic turbines are placed in the flow of a river or stream, capturing the kinetic energy from the water's flow rate rather than utilizing the potential energy from the head.

Horizontal Axis Wind Turbines

• Horizontal Axis Wind Turbines (HAWT) are the most commonly used and pictured wind turbines, which often have a long tower with between one and five propeller-like blades. The taller towers of large-scale turbines -- about 33 yards -- are able to capture some of the stronger and more consistent wind speeds that occur at higher altitudes. Smaller scale HAWT turbines are also used by DIY individuals in conjunction with motors that are made from scrap material, such as previously used permanent magnet (PM) motors or fabricated PM motors made from automobile rotors.

Vertical Axis Wind Turbines

• Vertical Axis Wind Turbines (VAWT) represent the other main type of wind turbine design, although it is suited more for lower wind speeds and has a lower overall efficiency than its HAWT counterpart. VAWTs have an appearance similar to that of an eggbeater and either use lift or drag to produce rotation speed. According to WrapWind, lift-based designs are often slightly more efficient than drag-based VAWTs, such as the Savonius design.