This article will help you know more about available power from a micro-hydro system.

P= η x g x Q x H

Where: η (eta) is the efficiency of the turbine being used.

For instance, a low-pressure micro-hydro scheme operating at 85th efficiency with a head height of 10 meters and a water flow rate of 500 liters per minute past a fixed point would deliver a power rating of approximately:

Power (P) = 0.85 * 9.81 * 0.00833 * 10 = 1007W or 1.0kW

As: 1,000 liters is equal to 1m3, therefore 500 liters is equal to 0.5m3. One minute is equal to sixty seconds, then a flow rate of 0.5m3 per minute is equal to 0.00833 m3 per second.

1.0kW might not seem much, however, this equates to over 8.7kWh ( 1.0 * 24 * 365 ) of free hydroelectricity annually. As power is proportional to the product of “Head x Flow”, increasing either of these 2 factors and/or the efficiency of the hydro system would lead to a rise in the generated power providing that the available water supply is reasonably constant throughout the year.

Also, the mechanical exchange of power from the rotating turbine to an electrical generator, or alternator, for example, belt drives, gearboxes, chains, etc. It will also lead to extra losses and reduced overall efficiency to maybe as low as 50 minutes or one hour.

Suitable Locations for Micro Hydro Power

Obviously, the most effective geographic locations for exploiting low-pressure micro-hydropower are where there's a perpetually flowing stream, stream or ditch as a result of high year-round rainfall. However, whatever your local conditions, low-pressure low-head micro-hydro turbines are offered for a whole range of website conditions.

The suitability of a specific location has to be known first by carrying out a site survey. An accurate assessment of water flow and head height, as well as key infrastructure elements such as pipe length, pipe diameter, and electrical cable run, ought to be considered to determine the feasibility of the project.

Also different things to consider such as, do you have a right to use the available water, can you get access across adjacent properties to put in the pipeline, do you need planning permits for a small turbine shed, dam or pipelines, and of course electrical power demand in watts (W) as to whether you wish an AC (Alternating Current) or a DC (Direct Current) offer for battery storage.

Micro Hydro Turbines

We have seen here that the potential energy of the water offered from a micro hydropower system is a combination of water flow and head height. The quantity of power available is, therefore, a mixture of high head/low flow, or low head/high flow, or anyplace in between. Water turbines convert the kinetic energy of the moving water into rotating shaft power so the choice of a specific turbine for a particular site is very important. Plus, the rotary engine type best fitted to any particular micro-hydro site will rely a lot on the characteristics of the site and of course the rotational speed of the electrical generator or alternator.

For low-pressure low-head micro-hydropower schemes, Reaction Turbines like the Francis, Kaplan or Crossflow turbines are best. This is in part to the fact that the turbine blades of a turbine are immersed in the water flow, so the extraction of energy from the water reduces the pressure of the falling water because it leaves the turbine housing returning to the river as a slow and controlled flow.

Overturn, turbines like the Pelton Wheel, Crossflow or Turgo Turbin use the rate of the moving water to rotate the blades instead of victimization water volume or pressure. Additionally, because the water is fast-moving it leaves the rotate housing returning to the stream as a quick high volume flow of water presumably making erosion and water flow issues within the river.

The choice of turbine-style can rely on the pressure head available and the water flows for the micro hydropower installation whether its a Reaction Turbine which uses pressure rather than velocity, or an Impulse Turbine which uses the velocity of the water rather than pressure.