Small Hydro

By Keith Heyde

Small hydro devices are water based generators that usually run at 10 mW or less in capacity. This means that small streams, partial dams, and even seasonal currents can all be used as the power source for small hydro generation devices.

Small hydro works by harnessing a smaller amount of pressure to spin a turbine. This may seem intuitive, but it is fundamentally different than large hydro processes.

In small hydro, often times the ‘catch’ or ‘water fan’ is placed at surface level with the water. This means, of the flowing current, only a small portion of harnessed by the small hydro device. This causes less total electricity generation than if the entire stream was captured. However, small hydro also does not have the ‘daming’ impact that big hydro does (no pun intended). Although there is a decrease in the current speed and potential for environmental repercussions, small hydro does not stop entire rivers (i.e. Hoover and the Colorado) nor does it lead to the flooding or drought extremes that big hydro often faces.

So what is the downside? There is a lack of efficiency associated with small hydro. This comes from not only the smaller percentage of net water harnessed, but also the fact that river surface speeds (as well as levels) vary greatly. Therefore, small hydro systems must be flexible to adjust to the surface levels. All in all, it causes small hydro to have consistency issues, akin to wind and solar.

Nonetheless, small hydro has played a large part in the energy world and continues to see huge advances. Small hydro facilities in Nova Scotia have taken the principles learned on rivers and applied them to tidal systems.

At the cutting edge of small hydro, new micro and mini projects are being developed to harness electricity in even smaller quantities. The idea is that beds of micro hydro generation units could be deployed over the surface (or bottom) of rivers. These generation beds would not inhibit river flow in any macroscopic sense, but they would harness a sum of very small electrical currents. This ‘bedded’ approach is ideal for the developing world where river flow and water is even more important than electricity.

For more information on small hydro take a look at the following websites:

Small Hydro Abou: http://smallhydro.com/about/

European Small Hydro Association: http://www.esha.be/

Small Hydro Handbook: http://www.smallhydropower.com/manual3.htm

For more information on small hydro facilities check out www.energygridiq.com for more information.