Onshore Savings This analysis considers the savings that are possible within National Grid’s £2,800m cost estimate shown on the pie chart below. The savings are shown in blue.
1. No 400kV pylons encircling the Duddon Valley and across Furness to Roose. The cost of erecting pylons from Carlisle to Roose works out at an average of 2.75m/km. Using this average figure the saving through not erecting 30km of pylons Silecroft to Roose is £82.5m. (In fact this is probably a low figure since the terrain circling the Duddon is likely to result in above average costs.)
2. To make way for the 400kV pylons, the existing 132kV pylons need to be removed. In addition, around the Duddon, temporary (lasts seven years!) Trident poles are to be installed. On the whole connection, a budget of £465m has been allocated over 153km for the re-configuration of the ENW network. If the 132kV pylons are left in place the saving over the route Silecroft to Roose is £90m and the saving over Bootle to Silecroft is £30m.
3. The cost of undergrounding through the Lake District National Park is £460m over a distance of 23.4km which is £19.6m/km. Since our route goes offshore north of Bootle, the undergrounding from Bootle to Silecroft is not required producing a saving of £193m.
4. National Grid has a budget of £348m for infrastructure. This covers items such as cable sealing end compounds (one not required at Silecroft - £600k, HDD under the railway at Silecroft is also not required, £780k