The UK leads the world in offshore wind, but getting electricity from North Sea turbines to demand centres in the Midlands and South can be tricky. Grid bottlenecks sometimes force operators to curtail generation, wasting clean power. HTS cables could be the solution, acting as low-loss ‘superhighways’ to move renewable energy exactly where it’s needed.

Professor Tim Coombs

A new Institute of Physics (IOP) report — featuring contributions from Professor Tim Coombs of the University of Cambridge’s Electrical Engineering Division — highlights a technology that could change the game: high-temperature superconducting (HTS) cables.

A Superhighway for Renewable Power

The UK is already a world leader in offshore wind, with bold targets to expand capacity. But transmitting electricity from the North Sea to demand centres in the Midlands and South is a growing headache. The same challenge applies to solar farms scattered across rural areas: how to deliver power without losing much of it along the way — or disfiguring the countryside with new pylons.

HTS cables provide an elegant solution. With ultra-high-power density and almost zero losses, they can carry vast amounts of electricity underground, quietly and efficiently, without the environmental scars of overhead lines.

Why HTS Matters Now

HTS isn’t just an incremental upgrade — it’s a toolkit for reshaping the UK grid:

• Efficient long-distance transmission: carry renewable power from remote coasts and fields to urban centres with minimal losses.
• Compact infrastructure: bury cables under streets instead of erecting pylons, easing land use conflicts.
• Stabilising renewables: superconducting magnetic energy storage (SMES) devices deliver instant back-up when the wind drops or the sun fades.
• Microgrids and resilience: strengthen localised energy systems, keeping rural communities powered during extreme weather.
• Urban deployment: a single HTS cable can replace several aluminium lines, critical in dense cities like London or Manchester. Emerging systems, such as those from Veir, promise to carry five to ten times the power of conventional cables.
• Cross-border interconnectors: the UK already trades 9.8 GW of power with Europe via interconnectors. HTS could make these links more efficient and reliable.
• Grid flexibility and reliability: HTS handles rapid, two-way power flows from distributed generation and protects against damaging surges — reducing the risk of blackouts.

Together, these features position HTS as more than just an alternative to aluminium: they make it a cornerstone technology for a modern, resilient, low-carbon grid.

Billions Wasted in Heat Losses

The economic case is just as compelling. Traditional aluminium cables strung from pylons bleed away between 5% and 10% of all generated electricity as heat. For the UK, that adds up to 25 terawatt hours a year — energy worth around £3.75 billion annually.

HTS cables, cooled by liquid nitrogen, have no electrical resistance. They can deliver electricity generated hundreds of miles away without waste, turning what is currently a massive hidden cost into an impressive national saving.

Superconductors vs Aluminium: A Step-Change in Transmission

The contrast with traditional power lines is stark. A single buried HTS cable can carry the same amount of power as multiple aluminium or copper overhead or underground lines.

In urban areas where land is scarce, this density makes a huge difference: far fewer trenches or pylons are needed. And because the cables can be buried directly, the visual impact on the countryside is minimal compared to new rows of pylons cutting across fields and hillsides.

For the public, this means preserving valued landscapes while still connecting to renewable power. For industry and government, it means removing the bottlenecks that threaten the grid as more variable sources of energy come online. “The real attraction of superconducting transmission is that it allows us to carry more electricity, over longer distances, without wasting energy or disrupting the environment,” explains Professor Coombs.

Making Best Use of Renewables

“The UK leads the world in offshore wind, but getting electricity from North Sea turbines to demand centres in the Midlands and South can be tricky. Grid bottlenecks sometimes force operators to curtail generation, wasting clean power. HTS cables could be the solution, acting as low-loss ‘superhighways’ to move renewable energy exactly where it’s needed.

Large solar farms across England, Wales and Scotland sometimes face a similar challenge. Superconducting cables could feed their output straight into the grid efficiently, without the need for long new transmission lines. HTS makes every unit of clean electricity count — reducing reliance on fossil fuels and easing the need for costly new power stations.”

Cambridge’s Contribution

Researchers at the Department's Electrical Engineering Division have played a vital role in turning the theory of superconductivity into viable engineering designs. Professor Coombs and his colleagues have worked on the fabrication of defect-free HTS tapes, improved cryogenic cooling systems, and new methods for integrating HTS with existing high-voltage alternating and direct current (HVAC and HVDC) grids.

The Division’s expertise spans both the physics of HTS materials — such as yttrium barium copper oxide (YBCO) and rare-earth barium cuprates — and the engineering challenges of deploying them. As Coombs notes, “Cambridge research has always combined fundamental discovery with practical application. In superconductivity, that means moving from the lab bench to systems that can really carry the nation’s power.”

Why Now?

Although initial investment costs are higher than for aluminium lines, the savings from reduced energy losses, greater grid reliability, and avoidance of new fossil-fuel generation more than offset these expenses over time.

With electricity demand expected to rise sharply due to the electrification of transport and heating, the case for more efficient transmission has never been stronger.

Other nations are already demonstrating HTS technology at scale: projects in Germany (AmpaCity), the US, Japan and China have shown that superconducting cables can operate reliably in real-world grids.

The UK now risks being left behind unless it acts quickly to move from research prototypes to substantial field trials.

The Next Step: A National Trial

The IOP report highlights the need for major UK demonstration projects — a buried HTS transmission link capable of handling real grid demands. Implementation of HTS cable technology typically falls between TRL 6 (Technology Demonstrated in Relevant Environment) and TRL 7 (System Prototype Demonstration in Operational Environment). Advancing HTS from this stage to full-scale deployment at TRL 8–9 will require overcoming several critical technical, regulatory, and supply-chain challenges.

Such a trial would not only prove performance and reliability, but also help establish standards and build supply chains for this emerging industry.

“This should be treated as a national priority,” says Coombs. “A field trial on British soil would place us at the forefront of a technology set to grow globally over the next half-century. The benefits are not just environmental — they are industrial and strategic too, helping the UK bridge the gap between promising prototypes and full-scale deployment.”

Export Potential for British Innovation

If the UK develops HTS transmission technology successfully, there may be opportunities to supply components and expertise to international projects, such as the European Supergrid and Asian renewable networks.

British-made superconducting cables, fault current limiters, and associated cryogenic systems could find niche markets abroad, supporting high-value jobs and the UK’s manufacturing base.

As countries expand renewable energy and look to reduce carbon emissions, demand for efficient, low-loss transmission is expected to grow. HTS technology could play a valuable role, offering innovative solutions and potential new markets over the coming decades.

Why Government, Industry and the Public should care

For the government, HTS represents a way to meet climate targets more affordably by reducing the need for additional generating capacity. For the electricity supply industry, it promises greater efficiency and resilience in the face of rising demand. And for the public, it means protecting landscapes while cutting bills and carbon.

“Superconducting transmission is not a futuristic dream — it is a practical solution to today’s challenges,” says Coombs. “By investing now, we can secure energy security, lower costs, and ensure the UK leads in a technology the world will soon need.”

This article was originally published on the Electrical Engineering Division website.