By the time Scotland’s Hunterston B nuclear power station closed in January of this year, its dual reactors had produced enough energy to power 1.8 million British homes for 46 years. It also provided over 500 jobs to people living in one of the country’s most deprived areas. Now, a project borne on the tide of a new era of energy production will take its place.
The new XLCC factory, to be built at Hunterston in 2023, will not generate electricity. Instead, the site’s 900 workers plan to create four high-voltage, direct current (HVDC) electricity cables that will stretch 3,800 km from Britain’s south coast, beneath the sea, to a patch of desert at Guelmim Oued Noun in central Morocco. From there, they’ll provide enough energy to power 7 million British homes and 8 percent of the UK’s total electricity requirement with 10.5 gigawatts of Saharan sun and wind by 2030.
Richard Hardy, project director at Xlinks, which developed the proposal, says people were “taken aback” by its scale. “But when you really step back, it almost becomes obvious that so long as you can get the power back, the project makes sense,” he says.
HVDC technology has existed since 1954, when Sweden connected the Island of Gotland to its mainland grid. HVDC cables experience low energy losses of around 2 percent, making them suitable for transporting electricity over long distances, compared to the 30 percent lost by alternating-current (AC) systems, which most energy grids operate on.
Until a few decades ago, HVDC only worked well when supported by strong, consistent energy-generating sources, like nuclear power plants. They also require converter stations the size of football fields to change the electricity back to AC at a cable’s terminus. The cables and current converter stations meant HVDC cost hundreds of millions of pounds. Installation can take decades. Then, in the 90s, a new system that used insulated gate bipolar transistors (IGBTs), or electronic switches, emerged. These allowed operators to mimic the voltage waveform of a strong energy source with that of weak sources, like solar and wind farms. HVDC projects still require enormous budgets, but the IGBTs allow them to use renewable energy sources. Operators were able to connect national grids with remote solar farms, and their popularity boomed.
HVDC systems can solve one of renewable energy’s biggest challenges: consistent supply. Wind farms generate too much energy when the wind blows and too little when it is still. Countries can access energy around the clock by connecting their grids to distant lands with different weather patterns.
The concept of connecting different countries’ grids also presents an economic opportunity. HVDC connectors give people access to the lowest prices. That provides an enormous benefit when regional events, like Russia’s invasion of Ukraine, prompt a rise in energy prices.
That’s one of the reasons the UK, where residential energy prices are now the second highest in Europe, has been among the fastest to adopt HVDC technology. Existing cables connect its grid with Ireland, France, Belgium, the Netherlands, and Norway. A new project to connect with Germany reached its funding target in July. And the Energy Security Bill now passing through parliament will accelerate the creation of HVDC projects by providing them with official licenses.
HVDC interconnectors have also attracted interest in other countries. The EuroAfrica interconnector aims to connect Greece with Egypt. An Italy-to-Tunisia interconnector is in the works, and Australia is hoping to provide Singapore with renewable energy via another ambitious interconnector called the Sun Cable.
XLCC’s task is noteworthy because no one has ever built such a long submarine power cable before. In fact, the current longest stretches only 720 km between Britain and Norway. The Morocco-to-UK power project requires something over five times longer.
Each 20-km chunk of the cable is produced by stretching copper or aluminum rods into a 69-mm-wide wire. A conveyor then hauls the wire to the top of a 180-meter tower, where an insulator is melted onto it over three hours as it descends to the factory floor. Once further layers of armored plating and bitumen are applied, a single meter weighs 70 kg.
The 20-km chunks must then be joined into a 160-km-long cable. This can be a very difficult task. The joints are the weakest parts of an HVDC cable and must be able to withstand the high temperatures and electromagnetic fields produced by the electricity-conducting core. To ensure every joint is perfect, joiners require specialist training that takes three years.
Despite the cable’s extraordinary length, sourcing the talent to complete the project presents the biggest challenge, according to Alan Mathers, XLCC’s project director. Dirk Van Hertem, professor of energy systems at the University of Leuven, reiterated this point. “This energy transition is requesting a massive amount of skilled labor,” he said. XLCC has developed a special course to be taught to 60 pupils at three North Ayrshire colleges this year to help meet the numbers needed to make the project happen.
Submarine HVDC cables are preferable to overland cables because ships can carry a lot more cable per trip than trucks. XLCC’s methanol-fueled hybrid vessel, which will cost up to £300 million (roughly $338 million), will carry 160 km out to sea at once—a truck could only carry 1 km.
Xlinks is spending £18 billion to build the project, which raises the question of its fiscal value. Van Hertem said the profit margin could be tight if energy prices fall to the levels seen before Russia’s invasion of Ukraine. But Richard Harcy, Xlinks’s project director, argues that the numbers add up. “If you step back slightly and you start thinking about how affordable generation from wind and solar is in Morocco, all of a sudden it sort of makes sense,” he says.
Nevertheless, unexpected damage at any of the cables’ 95 joints could enforce long and expensive periods of downtime. “Things do break,” Van Hertem said. “There are parts that go up to 700 meters deep. If that spot is where your cable is broken, it isn’t going to be too easy. These are thick cables. They don’t bend that well. It is possible. But it’s hard to fix.”
The concept of connecting the plentiful renewable energy sources of North Africa and the Middle East with the high-demand centers of Europe is over a decade old. A group of politicians and entrepreneurs have been promoting the idea through the Desertec Foundation since 2009. But concerns over cost and security hampered adoption. Western leaders have so far been reluctant to rely on what they see as an unstable, and sometimes hostile, region.
The threat of terrorist attacks stokes one fear. Utilities have presented attractive targets to violent extremist organizations over the past 40 years, and annual attacks on these facilities have risen by over 350 times at two points during the past decade, according to the Global Terrorism Index.
But professor Karen Smith Stegen, an expert in the politics of renewable energy at Jacobs University, says concerns about terrorism would be minimized once countries developed diverse networks of interconnectors. Even if the Morocco-UK system failed, the UK could rely on its other HVDC-linked sources of power, like Norway, France, and (soon) Germany. If it was unable to do so, “dormant” fossil fuel-based plants could fire up in as few as six minutes. Even well-funded terrorist organizations like Al-Qaeda lack the capabilities to bring an entire network down, Smith Stegen says.
The threat of a partner nation abusing an interconnector for political leverage is, for now, also off the table, because HVDC systems work more like streams than taps. “The issue with electricity is that it’s actually hard to just shut it off,” Smith Stegen says. “The electricity being generated has to go somewhere, unless you have massive storage, which has always been an issue.”
Effective long-term hydrogen storage solutions might change that. Hostile governments could seize the generation sites and store excess energy for later use, according to Smith Stegen. But she believes that politicians would do better to worry about HVDC systems’ vulnerability to cyber-attacks. She referred to the recent blackouts in India caused by China’s infiltration of its grid. “It seems that all this energy and electricity infrastructure is very vulnerable,” she says. “This is what people are learning.”
