By the time Scotland’s Hunterston B nuclear power station closed in January this year, its twin reactors having produced enough energy to power 1.8 million British homes for 46 years. It has also created over 500 jobs for people living in one of the most disadvantaged areas in the country. It is now being replaced by a project dedicated to a new era in energy production.
The new XLCC factory, due to be built in Hunterston in 2023, will not generate electricity. Instead, the site’s 900 workers plan to construct four high-voltage direct current (HVDC) power cables that will stretch 3,800 km from Britain’s south coast under the sea to a stretch of desert at Guelmim Oued Noun in central Morocco. From there they will provide enough energy by 2030 to power 7 million British homes and 8 per cent of the UK’s total electricity needs with 10.5 gigawatts of sun and wind from the Sahara.
Richard Hardy, project leader at Xlinks, which developed the proposal, says people were “stunned” by its size. “But when you really take a step back, it becomes almost obvious that as long as you get the power back, the project makes sense,” he says.
HVDC technology has existed since 1954 when Sweden connected the island of Gotland to the mainland grid. HVDC cables have low energy losses of about 2 percent, making them suitable for transporting power over long distances, compared to the 30 percent lost in alternating current (AC) systems, which power most power grids.
Until a few decades ago, HVDC only worked well when supported by strong, steady sources of energy such as nuclear power plants. They also need converter stations the size of football fields to convert the electricity back to AC at the end of a cable. The cables and transformer stations meant HVDC cost hundreds of millions of pounds. Installation can take decades. Then, in the 1990s, a new system emerged that used insulated gate bipolar transistors (IGBTs), or electronic switches. These allowed operators to mimic the voltage waveform of a strong energy source with that of weak sources such as solar and wind farms. HVDC projects still require huge budgets, but the IGBTs allow them to use renewable energy sources. Operators were able to connect national grids to remote solar farms, and their popularity boomed.
HVDC systems can solve one of the biggest challenges of renewable energy: constant supply. Wind farms generate too much energy when there is wind and too little energy when there is no wind. Countries can access energy 24/7 by connecting their grids to distant countries with different weather patterns.
The concept of connecting the networks of different countries also offers an economic opportunity. HVDC connectors give people access at the lowest prices. This offers a huge advantage when regional events like the Russian invasion of Ukraine cause energy prices to spike.
It’s one of the reasons why the UK, where residential energy prices are now the second highest in Europe, is among the fastest moving countries to adopt HVDC technology. Existing cables connect the grid to Ireland, France, Belgium, the Netherlands and Norway. A new project to connect with Germany reached its funding target in July. And the Energy Security Act now passing Parliament will speed up the creation of HVDC projects by giving them official licenses.