The 1.4-MW Slug of Auchrannie small hydroelectric project received approval from the Angus County Council of Development Standards Committee on Jan. 28 for installation in the Den of Arlie ravine near the town of Kirriemuir in Angus, Scotland. A definite start date for construction has not been announced, but the project proposal application indicates 18 months are needed to complete the run-of-river project on River Isla, estimated to cost about US$7.5 million.
Den of Airlie lies at the confluence of the Isla and Melgam rivers, 5.6 miles west of Kirriemuir and 1.2 miles northeast of Alyth. With the project approval, Scottish & Southern Energy, the second largest energy supplier in the United Kingdom, will harness waters from Isla River in the Den of Airlie, including waterfalls at Reekie Linn and the Slug of Auchrannie.
According to the planning report submitted to the standards committee, the Den of Airlie scheme is located in a Site of Special Scientific Interest (SSSI) in the River Tay Special Area of Conservation (SAC). The area was formerly a Scottish National Nature Reserve until its reclassification as an SSSI in 2012, according to the Scottish Natural Heritage organization. The SSSI is home to what some officials describe as the “world headquarters” for rare species of river jelly lichen.
The scheme involves a water intake on the bed of the River Isla; a 14-foot-diameter by 695-foot-long tunnel that contains a 5.9-foot-diameter penstock connecting to a partially underground powerhouse and tailrace, which empties water downstream back into the river.
Additional information in the approved proposal indicates “design and construction methodology have been very carefully considered, resulting in an exemplar hydro power development that makes best use of Scotland’s natural resources, contributes towards renewable energy targets, creates local wealth and can be delivered without adverse impact to either the Den of Airlie SSSI or River Tay SAC.”
Benefits associated with the project, according to the report, include:
• The generation of 4,300 MWh of renewable electricity per annum, thereby saving CO2 emissions of 2,225 tonnes per year;
• Over the expected 50+ year lifespan of the hydro turbine and associated infrastructure, this will deliver CO2 savings of 111,250 tonnes, which is equivalent to taking 15,580 cars off of Scotland’s roads for one year, or 312 cars off of the roads for the lifetime of the project;
• Immediate employment and supply chain opportunities estimated at £2.8 million (US$4.2 million);
• Long-term employment operation and maintenance opportunities estimated at £75,000 (US$ 113,000) per annum for the lifetime of the project;
• Economic benefit to the wider local community via local wealth creation and related spending;
• Educational value;
• Training and skills opportunities;
• Air quality; and
• Addresses climate change and its associated threats.
The Angus County committee, among a number of reasons, also approved the hydropower proposal because it thinks the attached Environmental Statement is acceptable and the project would contribute towards the generation of renewable energy and to the wider enhancement of the Den of Airlie SSSI, according to information in the project proposal application.