On Tuesday 8th February, Ben Mhor Hydro director Peter Drake and LDO Julia Campbell joined other Highland community groups on a site visit to Inverlael Hydro Scheme organised by Community Energy Scotland. The day began with a short presentation and information session by engineers from RWE Npower who run the scheme with contributions from Mott MacDonald civil engineers who built it. And fortunately for the less scientifically-minded among us, they provided a helpful little handout that included the following summary:
Located within the Lael Forest at the south end of Loch Broom, Inverlael Hydro Scheme takes water from a catchment area of approximately 16km2 including water flowing off Beinn Dearg and surrounding summits. Water is abstracted at two intake weirs on the River Lael and Allt Mor which feeds into 3.2km of buried pipelines to a powerhouse containing two turbines and generators as well as a transformer and associated equipment. The turbine discharges combine through a short buried tailrace pipe back to the River Lael before its discharge into the north side of Loch Broom. There is no reservoir storage so the turbines only use the water available in the rivers at the time.
The station is capable of generating 2.5 megawatts (MW) of renewable electricity, with a predicted output in a year of average rainfall of around 7200 MWhr, enough to supply approximately 1500 homes.
The scheme was consented under Section 36 of the Electricity Act 1989 by the Scottish Executive in July 2007, took 13 months to construct at a cost of just under £5M, and became operational in May 2009.
Armed with this background information, and sustained by a nourishing custard cream or two it was time for the party to hit the trail for Inverlael. Guided by representatives of RWE Npower and Mott MacDonald’s we all had a good look at the main intake weir on the River Lael, then up to Allt Mor to the intake there, and then following the route of the buried pipeline down to the powerhouse to see (and hear) the impressive generating equipment. Everyone was issued with the requisite earplugs and Alan Lipp of Npower fired up the turbines. It certainly was loud in the powerhouse and although we could hear the turbines outside, they became inaudible above the natural sounds of the nearby waterfall a few steps away.
The scheme at Inveralael is a lot bigger than what CCDC/Ben Mhor Hydro Ltd plan for Achavraie, but it gave us a good idea of what is involved and what the finished article might be capable of. Photos of work in progress show that the civil engineering involved a great deal of upheaval, digging, earthmoving and even some very impressive rock-blasting but once complete, remedial work has returned the surrounding ground to its former state. Most of the the pipework is buried underground so you wouldn’t even know it was there and where it crosses a gully, it has been encased in a very handy wooden bridge for walkers.
We were blessed with glorious sunshine and surrounded by evidence of recent tree-felling by the Forestry Commission we had a clear view of the snow-covered peaks above. You could have imagined yourself in the Canadian Rockies and all it required was a large bear to complete the scene. However, it was time to head back to the MacPhail Centre in Ullapool for some warming soup and some more turbine talk. Everyone agreed it had been a very useful and interesting day and looking at Npower’s staff, how encouraging it was to see so many young people following careers in engineering in the Highlands. Then everyone thanked each other for coming and we all returned to our various communities to ponder the next step.