Column: Interconnectors set for key role as green energy systems grow

Workers lay a NordLink subsea interconnector power cable to connect Norway and Germany at the Vollesfjord fjord near Flekkefjord, Norway May 31, 2018. REUTERS/Lefteris Karagiannopoulos//File Photo

LITTLETON, Colo., Oct 25 (Reuters) - Energy transition discussions tend to be abuzz with clunky terms such as carbon sequestration, refuse derived fuels, and distributed energy systems that green energy advocates hope will become common parlance as they become more widely used.

Less talked about but likely to become at least equally important are interconnectors, which are high-voltage cables that connect the power grids of different countries and allow for the trading of surplus electricity.

Several interconnectors are already used around the world, including the North Sea Link, the world's longest which allows for electricity produced by emissions-free hydropower in Norway to be supplied to Britain's industrial northeast, and for wind power to flow the other way.

UK interconnector cable links

More are in the works, and will play a critical role in allowing electricity transmission networks to distribute renewable energy to areas of need during periods of surplus, and draw green power from distant hubs during demand peaks.

MAXIMUM REACH

The uneven distribution of renewable energy supply and demand centres make interconnectors a critical component of any successful future energy system.

These cables - which in the North Sea Link's case stretches more than 700 km (435 miles) and is buried in parts below the seabed - allow for the movement of electricity from areas of surplus renewable energy supply to the households and businesses that aim to consume it.

In conjunction with grid-scale batteries - which store electricity for later use within the system where it was produced - interconnectors have the potential to allow countries with relatively low renewable energy capacity to access green power as needed, and lower emissions in the process.

Britain's National Grid is in the process of constructing a 760 km interconnector called the Viking Link between the UK and Denmark, which will set a new length record and trade surplus wind power between the countries. It's due online late next year.

Australia's Sun Cable has plans for a mammoth 4,200 km cable linking solar farms in northern Australia to Singapore, which relies on natural gas for over 90% of electricity and has ambitions to dramatically lower emissions by 2050.

The so-called Australia-Asia Power Link is set to begin construction around the middle of this decade.

Sun Cable interconnector from Australia to Singapore

The European Union has targeted at least 15% of its electricity systems to be interconnected by 2030, to encourage the development of renewable energy supplies even in countries that face energy surpluses on sunny and windy days.

Solar power producers in North Africa have also expressed interest in developing interconnector links to major consumer markets across Europe, which are currently under acute pressure to reduce reliance on natural gas and tap lower-cost green energy supplies.

KEY HURDLES

While interconnectors look good on paper, many face significant challenges before coming to fruition.

One major initial hurdle is cost. The UK-Denmark Viking Link is estimated around $2.25 billion, according to the World Economic Forum.

That equates to roughly $3 million per kilometer, which may be a stretch for many project developers, utilities and governments that have seen budgets sapped in recent years by COVID-19 and surging energy, supply chain and food costs.

Another major challenge is the length of time needed to produce the cables.

This is a fairly niche industry, and the major manufacturers of them - including Italy's Prysmian Group, which is building the Viking Link cable, and French firm Nexans - tend to need to focus on producing one contracted cable at a time, due to the specific and exacting requirements of each job.

Volatility in the price and availability of the main cable components is another challenge.

In addition to miles of high-grade copper, aluminium, and fibre optic cables, the core of each interconnector is typically filled with custom-made insulation that must withstand wide variations in heat and cold and accommodate tight coiling for years at a time.

Each cable must also be coated in resins that resist degradation when submerged in salt water, and be sheathed in tough metal alloys so they can withstand encounters with anchors and dredging machines.

All these factors add up to years-long delivery times and waiting lists, and often mean only a handful of new major interconnectors enter service in any given year.

But with renewable energy supplies expected to surge across every region in the years ahead, demand for the plumbing to get that power to major demand hubs will also soar.

And that means the currently obscure term 'interconnector' may soon go mainstream as an integral part of the global renewable energy lexicon.

Reporting by Gavin Maguire; Editing by Stephen Coates

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Gavin Maguire is the Global Energy Transition Columnist. He was previously Asia Commodities and Energy editor.