In assessing options for exporting power generated from Glen Almond we decided to focus in on 3 specific options for the site so as to establish a connection the national grid for distribution to areas of demand. The 3 routes identified and chosen from the feasibility study allow for the small scale generation to be carried to the grid however each offers a number of different advantages and disadvantages over the other.

Option 1: Upgrade an existing single phase 11kV connection to the national Grid via an 11km line.

Advantage – There would be no planning permission required to erect new poles, it would be a simple case of upgrading existing infrastructure.

Disadvantage - there may be limited extra capacity on the existing distribution network for any increase in generation that may occur in the glen restricting the preferred capacity of 2MW.

Although not all potential sites across Scotland would have upgradeable lines available literally next to the site, there is some grid infrastructure across the Scottish countryside. The former NOSHEB built a number of links both terrestrial and sub-sea even though they were not commercially viable, as they brought social benefits to communities that were being connected.

Option 2: There are other renewable schemes on the drawing board that may offer a shorter distance of 6km to a connection to the national grid in the local area.

Advantages – With the growth of renewable projects across the north of Scotland utilising both wind and marine solutions to generate power, new lines and spurs are being constructed and this sort of opportunity for sharing of cost amongst schemes may become more attractive as small scale generation uptake increases.

Disadvantages - In this route for our particular scheme the path to the other new renewable energy scheme requires the assent of a steep hill which increases the cost of implementation, whether underground or overhead methods are used, compared to normal.

Option 3: For routing power to the national grid for the specific site and the one that is of most interest to the team is a proposed route which includes placing a cable along a non-pressurised water supply pipe which is 5km long, used as part of the existing Breadalbane large scale hydro scheme. We have undertaken analysis of fixing the power cable to the base of the tunnel and carried out a critique of anchoring this cable through the tunnel using Computational Fluid Dynamics (CFD).

Advantages – As the pipe is already in place there would be few planning permission issues compared with digging a trench for under-grounding the cable or putting up new poles or pylons for overhead cables. This would also mean there is less of an environmental impact on areas of natural interest.

Disadvantages– There is a large amount of uncertainty regarding permission and health and safety rules that may need to be adhered to.

This route would also take advantage of shared costs with another scheme and if shown to work could allow for future resources to be exploited in other similarly geographically isolated areas.

Though our investigation was site specific, the proposed site is within the Breadalbane scheme, there are 8 other large hydro schemes across Scotland with similar characteristics. The map below outlines the areas of operation for each scheme. They are owned and operated by Scottish and Southern Energy at present, with further schemes in development.

Further information regarding medium voltage cabelling can be found here