Flexitricity provides the first opportunity for independent hydro generators to increase their revenue while helping to balance the electricity system.

Large hydro stations have been exploiting their flexible capabilities since the beginnings of the electricity industry.  Small hydropower schemes use technology that is virtually identical.  Flexitricity’s real-time aggregation system and process-led approach gives small generators the opportunity to exploit their flexibility and access premium energy prices.

Flexitricity's approach to small hydro generation is:

1. The turbine must be able to run at two or more power outputs.  
2. During wet periods when the reservoir may spill, the turbine runs continuously at high output, and flexibility isn’t available.
3. During drier periods, the turbine runs at low output to maintain reservoir level.  When required, the turbine increases to maximum flow for a short period.

Key considerations are:

Maximising generation

• Small hydro generators must take every opportunity to generate using available water. Spillway flow and evaporation loss must be minimised.

Storage

• Reservoir capacity is the key determinant of flexibility but must be considered against the size and run-off behaviour of the  catchment, seasonal weather variations and turbine rating.
• Reservoir level measurement is the best way to maximise the use of the available storage.

Turbine and system performance

• It is important to ensure that efficiency is adequate at all envisaged flowrates.
• Francis turbines provide peak efficiency just below the maximum output.  However, penstocks losses reduce at lower flowrates.
• Many Pelton or Turgo machines can operate efficiently at low flow, by shutting off one or more spear jets.

 

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