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Blair Castle, Perthshire

Blair Castle, Perthshire

Re-instatment of an early micro-hydroelectric scheme


This case study outlines the re-instatement of an early 20th century micro-hydroelectric scheme at Blair Castle in the Atholl Estates.


Energy demand can be reduced in historic and traditional buildings, however in larger buildings, especially non-domestic buildings open to the public, fabric improvements can only achieve so much.

At Blair Castle, the sawmill was powered by water from 1840 and in 1907, the owner of the Castle wanted to install electrical power to the castle and associated estate buildings. The sawmill scheme's existing infrastructure was therefore expanded to create a large enough network of channels, ponds and ditches - there was no single large body of moving water which could be tapped into on the estate, the whole network was manufactured.

The pipe that supplies the turbine, the penstock, was enclosed on site to minimise impact on the surrounding area of parkland. It ran to the turbine house, a plain brick structure with a pitched roof.

The advent of the National Grid, and the distribution of centrally generated electricity meant that the cost of running the hydro scheme could not compete. The Blair hydro system was therefore decommissioned in 1958 and the turbines sold for scrap. The turbine house was retained and repurposed for other estate uses and the penstock also found new use as a secondary water supply for the Castle's fire protection system.


It was the retention of the penstock that made the re-commissioning of the scheme viable. Around 2012, a feasibility study was conducted by The Blair Charitable Trust and the project was found to be possible, as long as the penstock could be re-used.

The original turbine house was re-used, along with the existing penstock. However, the network of ditches had to be excavated as they had since filled up. This was a simple process in concept, but in fact took six weeks to clear the 'four mile' ditch. A new turbine was also commissioned, and was delivered to site and installed in November 2013.

The hydro system was commissioned in 2014, and the turbine house formally opened by Fergus Ewing MSP in January 2015.


Noise management became a expensive issue when restoring the turbine house. The new turbine installed produced about 85 decibels. The lobby to the turbine house acted as a noise buffer, and acoustically sealed doors were also installed. Ventilation louvres also had to be designed with acoustic baffles. These measures were costly.

In total, the project cost £610,000 of which £200,000 was contracting and facilitating costs, and £143,000 weas the cost of the turbine and installation.

Electricity was first produced in September 2014 - surplus electricity is sold back to the grid.



The feasibility of the project was greatly improved by the fact that critical infrastructure (mainly the penstock) remained at Blair Castle. Additionally, the project team from Blair Castle had previous experience of hydro schemes completed locally which aided the completion of the project.

The case study has shown that the engineering requried to transport the water from the source to the generating house can be the hardest part and can be the most costly, rather than the turbine, dials and dynamo.

The re-use of mill and hydro systems should be encouraged from historic, cultural, economic and environmental perspectives. However, the potential re-use of a mill or other hydro-electric system may require consultation with the Local Authority planning department or Historic Environment Scotland. Discussions with SEPA (Scottish Environmental Protection Agency) may also be required as the process requires extraction from a watercourse.

After two years of operation, the estate staff have a good understanding of the running and maintenance of the hydro system and how the system is matched to the varying power demands of Blair Castle.

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