John & Sheila, Achanellan

The Technology

Hydro electricity works by having water driving a generator. Traditional water mills had large wheels in the flow of a river but modern systems are far more efficient and have a long pipe, or penstock, with a small outlet onto the turbine.

There are a lot of considerations for building a hydro scheme, and even a small one can be expensive, but once built they supply power for may years and can be more consistent than wind or solar. In a domestic or off-grid setting they may be sized small to generate in all but the driest summer, while larger commercial systems are larger and only run when there is sufficient water flow.

The important figures are the height between the damn and the turbine, known as the ‘head’, with rough ideas of these it is possible to make calculations around how much energy can be produced.

It’s important to remember that not every river has Hydro potential, with few low head sites being practical without 1000’s of litres of water per second available, a rarity in Lochaber. In the right locations run of river hydro is one of the lowest carbon sources of electricity available, but there are still environmental considerations, with sensitive habitats worth protecting.

Lochaber Environmental Group is currently developing a Hydro scheme in Glenachulish, with over 100m of head this will be over 500kW, providing power for over 400 homes. The scheme is in a forestry plantation and many of the tracks are already inp lace, minimising the environmental impact.

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