Much cheaper to go up rather than under for transmission

Burying high-voltage electricity cables underground is many times more expensive than using overhead lines with pylons, a report has shown.

The UK faces the prospect of hundreds of miles of new cables and hundreds more pylons across the countryside to connect new wind farms and nuclear power stations over the next decade.

Amid controversy over the use of overhead cables and pylons, which are typically 40 to 55 metres high, planning body the Infrastructure Planning Commission requested a report into the costs of the different options for carrying electricity.

The independent study by consultants Parsons Brinckerhoff, endorsed by the Institution of Engineering and Technology, showed that burying cables directly into the ground to avoid power lines across the landscape cost up to £20 million more per kilometre than using overhead cables.

It cost around ten times more per kilometre to build the underground system than overhead projects, and over the lifetime of the infrastructure it was around five times more costly to have the power lines underground.

Putting the underground cables in tunnels was even more expensive, according to the report, which did not consider the environmental and social costs of the different technologies.

But the relative cost of burying cables has fallen since the 1960s when the construction of the underground system was estimated at 20 to 30 times more expensive than overhead cables.

The study showed that burying cables directly in the ground cost between £10m and £24m per kilometre in construction and maintenance costs. Overhead lines were the cheapest option with the costs across the lifetime of the technology coming in at around £2.2m to £4.2m per km.

EMILY BEAMENT