Question to the Department for Energy Security & Net Zero:

To ask the Secretary of State for Energy Security and Net Zero, what estimate he has made of the costs of (a) undergrounding electricity transmission infrastructure and (b) developing overhead transmission lines.

Evidence published by the Institution of Engineering and Technology (April 2025) shows that the lifetime cost of underground transmission cables is around four and a half times higher than overhead lines.

As costs are borne by the electricity bill payer, the Government’s starting presumption for new transmission infrastructure is overhead lines. In nationally designated landscapes, undergrounding is the starting presumption.

A government commissioned study on the costs of innovative undergrounding methods for transmission lines over distances of 20km to 50km will be published in the near future.