Report says overhead power cables are cheapest option for National Grid

The Institution of Engineering and Technology (IET) published a study on the 'whole life' costs of installing new high-voltage transmission lines both over and under the ground.

The study showed that burying cables cost between �10m and �24m per kilometre in construction, maintenance and operating costs. Overhead lines are about five times cheaper, at between �2.2m to �4.2m per kilometre.

The Campaign to Protect Rural England (CPRE) said the study proved that plans to install miles of overhead lines needed to be rethought.

Campaigners also said the report vindicated the CPRE's claim that National Grid had previously over-estimated the costs of burying electricity cables at between 10 and 25 times the cost of overhead options.

But National Grid said the findings were broadly in line with previously-quoted costs, and that it had 'no inherent preference' between technologies.

Tom Leveridge, senior energy campaigner for CPRE, said: 'This evidence shows that the current public consultations into nearly 300 miles of new power lines have been proceeding with inaccurate information. We want National Grid to call a halt to any planned construction and restart the consultation process, but this time with the real costs and benefits made clear.

'We are also calling for a further study that looks at the wider social and environmental costs of energy transmission.'

National Grid spokesman Sara Wilcox said: 'From what we have seen so far, the costs seem broadly in line with what we have always put forward.

'The difference of around five times the cost is based on the 'whole life' costs which include building, installing, maintaining and operating. The 'ten times plus' figure is based on construction costs only.

'The report itself says these ratios can be misleading and it is better to use the absolute financial difference between overground and underground cables rather than using ratios.'