Water and electricity do mix…

06 November 2023

Alan Mathers of IWMA member XLCC will be one of the speakers at the IWMA conference on sustainable growth in the industry in November. He will be talking about standardisation […]

Alan Mathers of IWMA member XLCC will be one of the speakers at the IWMA conference on sustainable growth in the industry in November. He will be talking about standardisation and industrialisation, and how the industry can bring power from one continent to another and still turn off millions of tonnes of carbon output a year.

We have been finding out about the massive scale of XLCC’s Morocco-Devon project task; to bring solar-generated power from Morocco to the UK national grid along four 3,800km undersea cables.


Green technologies are becoming massively important to the wire and cable industry, as solar power, wind farms and other means of power generation eat up the world’s supplies of HV cables and all the elements associated with getting electricity from source to consumer.

One vital item in particular – high-voltage, direct-current cable – is in such demand that supplies could become very hard to come by as world production struggles to keep up. Direct-current submarine cables experience far lower transmission losses than AC cables over long distances, so efficiency is far greater.

“Up to about 60km, submarine cables can be standard AC types, but over greater distances HVDC is the way to go,” explained cable-making company XLCC’s project director, Alan Mathers.

XLCC is supplying the cable for UK company Xlinks’ plans for a solar farm in Morocco, from which cables will eventually carry power to Devon for up to seven million UK homes. The estimated £18 billion project will use four 3,800km cables, so efficiency is a major consideration.

“HVDC cable has transmission losses of about three per cent over a thousand kilometres,” explained Alan. ”We will be losing no more than about 13 per cent in total – including the one per cent at the converter stations at each end to change the current to DC then back to AC. A standard HVAC cable at our lengths would lose significantly more.”

The Xlinks project – of which Alan was initially a part – hit an early stumbling block: no one made that much HVDC submarine cable. The project will need around 16,000km over four years, and European production at the time of inquiry was only around 2,000km. The big makers were unable to increase production, so despite the huge cost of entering the market, separate company XLCC was born in 2020 – a single-product company to serve, at the time, a single customer. It was potentially a very expensive risk.

The cable element of the project is extraordinary: XLCC needed a location matching fairly strict criteria – the need for planning approvals (including from air traffic control) for a 185 metre extrusion tower; skilled labour; training a new generation of expert cable jointers, and most important of all, the requirement to build a factory near the water in a deep-water port – since each new delivery length of cable is 160km long and weigh 10,500 tonnes. Not the sort of thing you would want to move a few kilometres from factory to port.

The project’s new, state-of-the-art, cable-laying ship has a 26,000 tonne payload and will lay two lengths of cable at a time – 21,000 tonnes’ worth. Each 160km section will take around eight days to lay – in good weather – in 200m-700m waters off the coasts of north Africa, Portugal, Spain and France before reaching Devon, 3,800km away. Then they turn round and start again on two more cables, forming two “bipoles” – two direct-current circuits. The process will take three to four years.

The company found a site at Hunterston on the Firth of Clyde – some of the UK’s deepest coastal waters. The area lost its nuclear power plant in 2022, so XLCC could pick up some of that plant’s skilled workers when its factory goes online. The plan is to start making cable in 2028, get the first pair in the water by 2030 and the second pair by 2032.

All in all, XLCC had to dip not a toe into the market, but the whole corporate body: “Very few places in the whole of Europe would have been suitable sites,” explained Alan. “With the need to start up, develop, certify and start producing our cable, we were looking at five years of money going out.”

But plans have been carefully laid, so the company will build the first three of six production lines for some shorter export cables (to bring power onshore from offshore wind farms) of perhaps 200km – 300km and for network reinforcement projects (moving power with offshore cables from point of generation to demand area). The factory can then be certified for the production of this cable design.  When Xlinks is awarded a government “Contract for Difference” by 2025 the capacity can be increased to six production lines and production ramped up dramatically.

It looks like the company’s faith is going to pay off in a big way. The growth in the market for HVDC cable means XLCC is likely to be in business supplying its only product – 525kv DC, aluminium-cored  cable – from more than one factory for at least the next 20 years, employing thousands of people in the process.

“Unlike the other big cable makers, we will supply just the one product, at a discount to the typical market price,” Alan continued. “We will start small at Hunterston, with three lines, each capable of producing a metre of cable a minute, each metre weighing 70kg, for which we already have sales understandings. There are lots of generation projects in Scotland: buying our cable, though its power carrying capacity might exceed immediate development needs, will be a good investment for the possibility of future expansion, in addition to being cheaper than alternatives,” Alan explained.

And let’s not forget a vital part of the operation: the cables themselves. Xlinks will need four 3,800km cables, but Hunterston will be able to make, and its ship to lay, no more than 160km at a time, in 20km sections. They will need a way to join them together…

That’s where XLCC has again planned ahead: “Short of poaching the 60 expert jointers we need from factories in Italy, Germany, Sweden or wherever, we went back to the start and wrote course materials for local engineering college courses,” Alan explained. “This year we started to recruit apprentice jointers, so over the next three years we will train them to become fully certified.

“When we make the first test cables in 2026 and get it certified in 2027, they will be ready for the first sections of the finished cable in 2028.”

The project that started out looking like a huge leap of faith now looks like making XLCC the world’s biggest supplier of the most-in-demand long-distance cable for some years to come. The Morocco-Devon project, for example, is known within the company as Xlinks-1, since there are already tentative plans for two more long-distance connectors. “These cables are going to be in demand everywhere as countries around the world seek to fulfil their net zero commitments,” suggested Alan.

And despite its scale, the enterprise will be gloriously green in nature: “Some objectors have complained that the project isn’t really eco-friendly because the removal of by-products from the XLPE plant will produce the about 300 tonnes of CO2 a year.

“While that might be true, they ignore the fact that when the power comes online, that 300 tonnes of CO2 will be offset in about 15 minutes, since the power plant will be saving around 10 million tonnes of CO2 a year that would have been generated in conventional power stations…”


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