We aim to use the enormous amount of rain that falls on Ardtornish, over 90 inches a year, to produce electricity in a way that doesn’t damage our environment. The rain fills our rivers and reservoirs, and the energy from the weight of water travelling under pressure down our pipelines (known as penstocks) turns specially designed turbines.
The turbines spin generators which produce electricity. The water returns to the river and from there flows to the sea. The electricity is sold to the national grid, providing Ardtornish with the income it requires to help do the things we need to do, and consumers with a supply of green, clean energy.
On the river Rannoch, we have replaced the earlier 1996 ‘run of river’ hydro scheme with a cascade system of three independent hydro schemes. The two furthest intakes divert additional water, via a low pressure aqueduct pipe into Loch Tearnait, which acts as a water storage reservoir. The loch is fed by both these new water intakes and the river and burns that flow into it naturally. The Tearnait hydro intake feeds this water into the 1000m long penstock which creates a 60m head (i.e. 60m pressure of water) at the new Tearnait power house at the eastern edge of Strath Shuardail.
Having produced up to 700 kW of electricity in that (the Tearnait) power house, the water returns to the river and fills the newly-created Lochan Lùb an Arbhair (translated from the Gaelic as the bend or meander around the corn field). This new loch was created by the 2012 Rannoch Dam – probably the largest thing to be built in Morvern since Ardtornish House in 1884. The water flows from dam down another penstock, generating a 69.5m head and up to 1500 kW of output at the Rannoch Power House.
From there it re-enters the river, and few hundred metres downstream the water is impounded again. This time it enters a low-head pipe under the road, emerging again at the top of a new (2016) Archimedes Screw Turbine, which sits beside the river at Achranich. It uses the water a third time, before finally it is discharged into the river to flow the few remaining metres downstream and downhill to the sea.
We calculate that we use all but a very few metres of head to generate power from the top of the cascade to the bottom.
In 2015 we completed another 800kW scheme, at Uileann in the White Glen. It catches water from three sources, but has no water storage capacity – so is known as a ‘run-of-river’ hydro. Like Tearnait and Rannoch, it uses a turbine built by Gilkes of Kendal.
During 2017 we built a final hydro power station, the Socaich scheme, which catches water from several intakes on the Achranich hillside and diverts it into Lochan Lùb an Arbhair. Before flowing into the lochan, it goes through a Gilkes turbine, producing up to 325 kilowatts of power. The extra flow into the lochan joins the other sources to flow through the Rannoch turbine, generating again. Then it enters the Archimedes screw turbine – so, like water passing through the Tearnait hydro scheme, each drop passing through the Socaich scheme is used three times before finally flowing to the sea.