Question to the Department for Energy Security & Net Zero:

To ask the Secretary of State for Energy Security and Net Zero, whether Ofgem have made an estimate of the relative costs per KM of installing (a) overhead, (b) underground and (c) offshore electricity transmission cables for energy transmission infrastructure.

Ofgem estimates of the relative costs of overhead, underground and offshore electricity transmission cables vary significantly depending on various factors such as technology types, voltage levels and locations. Due to commercial sensitivity, Ofgem cannot not share specific estimates. However, as set out in the Institution of Engineering and Technology’s 2012 study, offshore cables have considerable cost and technical challenges and can have substantial impacts on the marine environment. Undergrounding is usually by open trenching with costs between 5-10 times those of overhead lines.