Expanding Britain’s electricity transmission network using overhead pylons offers the most cost-effective route to achieving net zero emissions targets, according to a new report published by the Institution of Engineering and Technology (IET).
The report, produced in partnership with consultancy Mott MacDonald, found that underground cables are, on average, 4.5 times more expensive than overhead lines. The cost differential increases with offshore infrastructure, with high-voltage direct current (HVDC) point-to-point connections costing around five times more and offshore HVDC network systems connecting multiple sites costing up to 11 times more.
“Access to a cleaner, more affordable, secure supply of energy requires the biggest programme of electricity transmission development since the 1960s,” said Professor Keith Bell, chair of the IET project board.
The report underscores the need for a significant expansion of the UK’s transmission grid to support the integration of new low-carbon energy sources and facilitate the country’s net zero ambitions. It also calls attention to ongoing supply chain constraints, particularly in cable manufacturing, which are contributing to delivery delays and rising prices.
The IET emphasised that while overhead lines may present the lowest cost in many cases, no single solution fits all project scenarios. “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,” said Katherine Jackson, a member of the report’s project board.
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.”
The findings are intended to support policy and planning decisions amid increasing pressure to modernise the UK’s power grid. “This report provides a rich information resource on the technology choices for development of the electricity transmission network,” said Professor John Loughhead, also a project board member.
David Reid, lead author and global practice leader at Mott MacDonald, said the report offers “valuable insight into the different technology options available and their relative merits.”
Energy Minister Michael Shanks welcomed the report, stating that upgrading the grid is essential for reducing costs for consumers, boosting economic growth and creating new jobs.
The report was independently commissioned and contributes to the broader national debate on how best to accelerate grid development in line with decarbonisation goals.
