Technical details for Hydro

For the majority of technical aspects on we refer you to the British Hydro Asociation who have prepared an in-depth document detailing many of the technical aspects of a hydro system. Microhydropower.net are also a good source of information. The flow duration curve is a partular aspect that we discuss below since the optimum design of a Micro High Head Hydro system is highly dependent on knowing the accuracy of this curve..

Flow duration curve.

An accurate detrmination of the flow duration curve is essential in the development of an optimum M3H design. The top right hand figure shows a typical flow duration curve from an upland, site.

The thick black line describes the flow. The vertical axis is the flow in the river. The exceedance is the proportion of time that the flow is equal to, or greater than, the indicated flow. For example, the figure indicates that 67% of the time the flow is greater than or equal to 100 l/s (red lines and dot).

In order not to impact the aquatic llife of the stream and the dependent natural habitat supported by it, the hydro electric system must leave a residual flow in the stream at all times. Furthermore, it is never financially viable to abstract all the available flow.

The amount of flow actually abstracted by the system will resemble something like the green line in the bottom right hand figure. The range of flows abstracted and the efficiency of the system over the flow range depends on both the penstock (pipe line) and turbine design.

Heidra's M3H design allows the maximum viable range of the flow duration curve to be captured, working at high efficiencies across the complete range.