Hydro Power Technical Guidance

Hydro Power Technical Guidance

Yield

There are key factors in calculating the power likely to be gained from a hydro system:

"Head" - the vertical distance between the highest and lowest points at you site, measured in metres.

"Flow" - the amount of water passing a point, measured in litres per second.

The power available is calculated from the formula:

head x flow rate x gravity x 0.75(to allow for inefficiencies) 

5m of head with 14 litres per second will yield:

5 x 14 x 9.81 x 0.75 = 515 Watts.

As hydroelectricity is extremely reliable, this should produce around 4MWh per year (an energy efficient house will consume around 5MWh per year)

Cost
The amount of civil engineering works required for a hydro installation vary widely and there is no such thing as a typical site.
However as a rough guide, a 1kW system is likely to cost between £10,000 to £20,000.  Whilst this may sound expensive in comparison with other renewable sources, remember that the yield is constant rather than intermittent.

Environment

Rivers and streams are delicate ecosystems, and it is highly unlikely that you will be able to divert all of the water to a hydro turbine.  The environment agency must always be consulted early in the planning of a project

Turbine Selection

The chart below shows how different turbines are suited to different operating conditions, and is an aid to turbine selection.