Baseload, Hydropower

Scotland Moves Forward on a 10-MW Small Hydroelectric Project in Den of Arlie

Development in Den of Airlie will move forward now that the Scottish Environmental Protection Agency (SPEA) is satisfied with the results of a four-year-long environmental impact study submitted by Airlie Castle property owners. Formerly a nature reserve, but now an area of special scientific interest, the area’s study indicates a small hydroelectric project would have needed economic benefits to the community and have no major adverse negative impacts to the environment.

Den of Airlie lies at the confluence of the Isla and the Melgam rivers, 9 km west of Kirriemuir and 2 km northeast of Alyth in Scotland. Scottish Natural Heritage, a government organization, confirmed December 2012 that the area is no longer a National Nature Reserve.

Scottish & Southern Energy (SSE) plans to use a six-mile stretch of the Isla River in the Den of Airlie nature reserve, including waterfalls at Reekie Linn and the “Big Slug” at Auchrannie, for a 10-MW run-of-river small hydroelectric project capable of generating up to 30 GWh in an average year.

The project is planned for construction near Airlie Castle.

Cost for the project is not immediately known, but a weir would be built across the Big Slug waterfall. According to SEPA, the project’s intake and tailrace will incorporate fish mitigation as per the “Guidance for Developers of Run-of-River Schemes.”

The Isla River feeds in to the Tay River Special Area of Conservation in the north central region of the Scottish Highlands. According to the Joint Nature Conservation Committee, a statutory adviser to the government of the United Kingdom, the Tay River supports a high-quality Atlantic salmon population. The committee reports that salmon rod catch returns indicate Tay is consistently one of the top three salmon rivers in Scotland.

SSE estimates the completed project will produce enough power to supply more than 6,500 households.

Part of the scheme will use a 200-meter-long water delivery channel at the Big Slug at Auchrannie that would involve water being fed through a penstock to a generating station before being returned to the Isla River six miles downstream, just above the village of Alyth.