Overhead pylons offer the most cost-effective way to expand Britain’s electricity grid and meet net zero targets, according to a major new report from the Institution of Engineering and Technology (IET).
The IET found that underground cables are, on average, around 4.5 times more expensive than overhead lines.
Offshore high-voltage direct current (HVDC) point-to-point cables cost around five times more, while offshore HVDC networks connecting multiple sites are around 11 times more expensive.
The report, released today, stresses that each technology must be judged on its merits in specific circumstances, balancing cost, engineering challenges and environmental impact.
It highlights that supply chain bottlenecks, particularly in cable manufacturing, are affecting delivery times and prices.
A major expansion of Britain’s transmission network is needed to connect new low-carbon energy projects and support the transition to net zero, the report said.
Professor Keith Bell, chair of the IET project board, said: “Access to a cleaner, more affordable, secure supply of energy requires the biggest programme of electricity transmission development since the 1960s.”
Professor John Loughhead, member of the report’s project board, said: “This report provides a rich information resource on the technology choices for development of the electricity transmission network.”
Katherine Jackson, another project board member, said: “In practice, the costs and benefits of the different technologies depend very much on the specifics of individual projects, so there is no one-size-fits-all solution.”
Professor Andrew Lovett added: “When deciding between underground cables, overhead lines or subsea cables off Britain’s coast, we must consider a complex range of impacts unique to each project.”
David Reid, lead author of the report and global practice leader at Mott MacDonald, said: “This report provides valuable insight into the different technology options available and their relative merits.”
Mike Reader MP, chair of the All-Party Parliamentary Group on Infrastructure, said: “This comprehensive examination of the costs associated with electricity transmission network technologies represents a significant contribution to the ongoing public debate.”
The study was produced independently by the IET and prepared by consultancy Mott MacDonald.
Energy minister Michael Shanks welcomed the report, saying upgrading the grid was vital to protect billpayers, drive growth and create jobs.