The right technology at the right price

A blog by Bless Kuri, SSEN Transmission’s Director of Strategic Energy Planning

A few weeks ago, the Institution of Engineering and Technology (IET) published a long-awaited and comprehensive study that compares the typical costs and characteristics of the various electricity transmission technologies that can be considered for transporting high volumes of power over long distances.

The report provides valuable, independent insight that is particularly relevant to our planned work in the north of Scotland, where we face unique challenges in expanding and upgrading the transmission network to support Scotland and the UK's energy security and clean power targets.

It’s vital that we get this right and move swiftly. To quote Professor Keith Bell, Chair of the Project Board for the IET report: “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 since the 1960s.”

Cost

The IET’s study confirmed what was already well known in the industry: that there are significant cost disparities between different electricity transmission technologies.

As the report highlights:

• Buried alternating current (AC) underground cables are, on average, around 4.5 times more expensive than AC overhead lines;
• Installing the cables in newly build tunnels is around two and a half times more expensive still;
• An offshore high voltage direct current (HVDC) point-to-point cable is around 5 times more expensive compared to an equivalent AC overhead line;
• An offshore HVDC network connecting multiple sites to the onshore grid is around 11 times more expensive compared to an AC overhead line.

It is important, of course, that each technology is judged on its merits in each specific grid development context, considering environmental impact, engineering challenges and local impacts. That’s why, for example, we are working in partnership with National Grid Electricity Transmission (NGET) to build the Eastern Green Link 2 subsea cable project between Peterhead in Aberdeenshire and North Yorkshire: moving enough clean energy to power two million homes.

But the different costs of different technologies detailed in the IET report are clearly significant – and with the bill ultimately landing on the door of the electricity bill payer, the importance of careful planning and consideration when selecting the appropriate technology for each project is clear.

The numbers speak for themselves. If we are to have a transition that is just and affordable – for the country, industry and billpayers – we cannot grow the grid by typically using the most expensive technologies.

Navigating the Scottish terrain

In the north of Scotland, the rugged landscape and dispersed population present further distinct challenges for transmission infrastructure and add even more cost.

It is evident, then, that overhead lines continue to be the most practical and cost-effective solution, with the ability to transport the most power. But we recognise the visual and environmental concerns they may raise, and that’s one of the reasons why engaging with local people on the options for new infrastructure is so important.

Strategic investment for a sustainable future

Our commitment to developing the electricity transmission network in the north of Scotland through our planned investment programme of more than £22bn is clear. This will unlock the potential for renewable power across the region and deliver energy security – the pathway to lower consumer bills – and support economic growth.

The net zero economy in the UK grew by more than 10% last year alone, and the green revolution is happening in areas well beyond the economy of London and southeast England – in Scotland, nearly one in 25 workers are employed in a net-zero related role.

The IET's report provides a valuable framework for understanding the complexities and trade-offs involved in transmission infrastructure development. At SSEN Transmission, we are dedicated to making informed decisions that balance cost, environmental impact, and community needs, ensuring that our projects contribute powerfully to the energy future of Scotland and the UK.