A tale of two hydros – Lake District and Snowdonia. Bespoke they certainly are!

Craflwyn and Afon y Cwm

Stickle Gill – site of the other 100kw hydro

  • It’s an interesting time working on the next set of hydros. The one area which I’m learning about is the bespoke nature of hydros. Early on and in the naive stage of development I looked for the silver bullet for hydros. Namely a unitised and standardised approach whereby we could attack the cost envelope by pre-fabrication and buying job lots of components.

The fact that each one is bespoke has really come to pass in a big way around two hydros we are scoping – Garry is working on Stickle Gill in the Lake District and I am working on Craflwyn in Snowdonia. You would think that because they have a similar flow characteristic they would cost the same and we could order multiples of the same components. How wrong  – it’s a good learning time for us.

  • Both hydros are rated about the same which is 100kwp. But this is dictated by the feed in tariff level and not by water availability.
  • Craflwyn has 130 meters of head vs the 90m on Stickle Gill. This is dictated by topography and geology (where can we put the weir and the pipe can exit the water course)
  • There is £45k difference in the turbine buildings. The Craflwyn building will be semi buried – this is dictated by aesthetics and a sites significance.
  • The Craflwyn pipe costs £35k more because it is 400m longer.
  • Stickle Gill is expected to generate 40MW less per annum than Craflwyn – This is dictated by the size of the catchment combined with the abstraction regime (how much above the average flow can we abstract)which again is dictated by ecology (what lives there and how much water does it need)
  • The difference in head and water flow means we need slightly different turbines to deal with more or less water at more or less pressure.
  • Then we get to the grid connection. The Craflwyn grid connection is slightly more because of its distance from the main grid

At the end of the day – it’s a weir, pipe, power house and grid connection but then you get into the nitty-gritty  to optimise and this means bespoke. But as Garry and I develop these systems in tandem we can share the lessons from two different places.  we can still get savings based on more than one site esp. in contract development, turbines even if they are slightly different, pipes and so on. But its not a one size fits all approach

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