Conclusions

Considering the financial challenges of any upgrade for distribution and transmission, we believe that  the idea of running cables through supply tunnels such as the one in Glen Almond may work but only if delivery & installation costs are comparable to the costs of under-grounding a cable. At April 2010 prices, the overall price per km for sub-sea cabling is approximately £165,000 indicating that, for the tunnel option to be viable, cost of transporting and installing the cable should not exceed £65,000 per km.

The tunnel owners would have to agree a method statement and regime for the installation, fixing and maintenance of the cable.

Sub-sea power cable is designed for use in harsh environments. Though there is the potential for erosion and corrosion, the lack of salt water & relatively low water speeds give the potential for a long life of installed cable.

Further areas of work:

There are some areas we feel would benefit from further investigation:

The laying of sub-sea cables through tunnels - Draw up a methodology in conjunction with the owners of non pressurised tunnels to agree access arrangements and a continuation and enhancement of the CFD model form 2-D to 3-D.

Logistic of moving the large and heavy sub-sea electrical cable - From the factory to site, the choice of supplier would play significant part in the overall cost.  Should this project be progressed, the cost of delivery to site is a significant factor due to the locations of the manufacturing facilities. If there was potential for schemes in the southern part of the British mainland for example, then the Italian factory may be more cost effective than from the Scandinavian located factories. Scandinavian countries would be more suitable for any projects developed in the northern half of the country.