By the time Scotland’s Hunterston B nuclear power station closed in January this year, its two reactors had produced enough energy to power 1.8 million UK homes for 46 years. He also provided more than 500 jobs to people living in one of the countries most disadvantaged areas. From now on, a project carried by the current of a new era of energy production will take its place.
The new XLCC plant, which will be built in Hunterston in 2023, will not generate electricity. Instead, the site’s 900 workers plan to create four high-voltage direct-current (HVDC) power cables that will stretch 3,800km from Britain’s south coast, under the sea, to to a desert area in Guelmim Oued Noun, in central Morocco. From there they will provide enough energy to power 7 million UK homes and 8% of the UK’s total electricity needs with 10.5 gigawatts of Saharan sun and wind by 2030.
Richard Hardy, project manager at Xlinks, which developed the proposal, says people were “surprised” by its scale. “But when you really take a step back, it becomes almost obvious that as long as you can get the power back, the project makes sense,” he says.
HVDC technology has been around since 1954, when sweden connected the island of Gotland to its continental network. HVDC cables experience low energy losses of around 2%, making them suitable for transporting electricity over long distances, compared to the 30% lost by alternating current (AC) systems, on which most energy networks operate.
Until a few decades ago, HVDC only worked well when supported by powerful and constant sources of power generation, such as nuclear power plants. They also need converter stations the size of football pitches to switch electricity back to AC at the end of a cable. Cables and power converter stations meant that HVDC cost hundreds of millions of pounds. Installation can take decades. Then, in the 1990s, a new system using insulated gate bipolar transistors (IGBTs), or electronic switches, appeared. These allowed operators to mimic the voltage waveform of a strong power source with that of weak sources, such as solar and wind farms. HVDC projects still require huge budgets, but IGBTs allow them to use renewable energy sources. Operators were able to connect national grids to remote solar farms, and their popularity exploded.
HVDC systems can solve one of the biggest challenges of renewable energy: a constant supply. Wind farms generate too much energy when the wind is blowing and too little when it is still. Countries can access energy around the clock by connecting their grids to distant countries with different weather conditions.
The concept of connecting the networks of different countries also presents an economic opportunity. HVDC connectors give people access to the lowest prices. This offers a huge advantage when regional events, such as Russia’s invasion of Ukraine, cause energy prices to rise.
This is one of the reasons why the UK, where residential energy prices are now the second highest in Europewas among the earliest adopters of HVDC technology. Existing cables connect its network with Ireland, France, Belgium, the Netherlands and Norway. A new project to connect with Germany reached its fundraising goal in July. And the Energy Security Bill Now going through parliament will speed up the creation of HVDC projects by providing them with official licenses.