Case Study - High Head Hydro

Gleann Casaig Hydro

Loch Lomond and The Trossachs National Park

The Gleann Casaig Hydro Scheme is located in the Loch Lomond and The Trossachs National Park.

Green Cat Renewables provided post planning management, detailed scheme design, planning conditions discharge, technical procurement services and Client’s Engineer services.

The key elements of this project are:


The scheme has 1 main intake and 5 secondary intakes which provide water to a pressurised pipeline.

Due to the extremely low gradient of the top section of the pipeline, the main intake was required to be over 5m tall which posed major challenges due to the poor ground conditions and very limited site investigation before works started due to lack of access.

Two types of secondary intake were used on the scheme: 2 shuttered concrete and 3 prefab steel box intakes.


The pipeline from the main intake to powerhouse is 2,800m long. The upper, low pressure section is of HPPE and the lower, higher pressure section ductile iron (DI).


The powerhouse is a steel portal frame with concrete block infill. Planning conditions required that the roof is covered with grey profiled tin and external walls are clad with vertical dressed timbers. The acoustic doors and louvres ensure that sound emissions are kept within planning requirements.

The scheme has an 11kV high voltage connection which requires a private substation (transformer and switch gear) which is contained within a prefab unit.

Key Data
  • Client: H14 Energy
  • Power: 500kW
  • Gross Head: 208m
  • Maximum Flow : 293 litres/second
  • Turbine Type: Pelton
  • Pipeline: 2.8km
  • Predicted Average Annual Energy Production (AAPE): ~1,520 MWh
  • Date of Commissioning: December 2016
  • National Park