Published: Tue 29 Apr 2025
A comparison of electricity transmission technologies: Costs and characteristics
An Independent Report by Mott MacDonald in conjunction with the IET.
As the UK embarks on its most ambitious grid upgrade since the 1960s, this comprehensive report sheds light on the various technologies available to re-wire Great Britain, ensuring a greener, more efficient, and secure energy future.
Report downloads
Key insights
- Cost Comparisons: Discover why underground cables are, on average, 4.5 times more expensive than overhead lines, and how offshore HVDC solutions can be up to 11 times more costly.
- Technological Merits: Understand the importance of evaluating each technology based on environmental impact, engineering challenges, and local considerations.
- Supply Chain Dynamics: Learn about the bottlenecks in cable manufacturing and the necessity for long-term partnerships with providers.
Why it matters
To harness Britain's wind energy resources and meet the growing demand for electricity, a significant expansion of the transmission network is essential.
This report provides detailed options for enhancing the existing network and adding new capacity, summarising the average lifetime cost of providing 1 MW of new network capacity over a distance of 1 km.
Beyond costs
Explore the non-cost factors that play a crucial role in grid development, such as visual and environmental impacts, sustainability, and engineering challenges.
From underground cables to subsea solutions, each technology offers unique advantages and considerations.
A collaborative effort
Coordinated and published independently by the IET, with research conducted by international engineering consultancy Mott MacDonald, this study updates previous data from 2012 and incorporates insights from a wide range of industry experts.
Hear from the experts
Professor Keith Bell
Chair of the Project Board for the IET Transmission Technologies report, said:
"As an essential part of the country's aim to reach net zero, the UK is decarbonising its production of electricity and electrifying the use of energy for heating, transport and industry.
"Access to a cleaner, more affordable, secure supply of energy requires the biggest programme of electricity transmission development in two generations."
Professor John Loughhead
Member of the report’s Project Board and IET Fellow and Past President said:
"This report provides a rich information resource on the technology choices for development of the electricity transmission network.
"It will help inform and stimulate essential discussions between policy makers, local authorities, local communities and bill payers as options are considered."
Professor Andrew Lovett
Member of the report’s Project Board and Professor of Geography at the University of East Anglia added:
"This situation is complex with no simple environmental choices. 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.
"Each technology needs to be evaluated based on its specific context, including engineering challenges, local impacts, and costs."
Katherine Jackson
Member of the report’s Project Board and an energy specialist said:
"The insightful relative lifetime costs are based on several assumptions and will be subject to global inflationary pressures.
"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."
David Reid
Global Practice Leader, Integrated Electricity Networks, at Mott MacDonald, and lead author of the report, said:
"The country’s electricity infrastructure will play a vital part in achieving the UK’s net zero targets, but it needs to be significantly expanded and upgraded. This report provides valuable insight into the different technology options available and their relative merits.
"It will be a vital resource in supporting stakeholders with accelerating the necessary infrastructure development needed for UK society to achieve net zero."