According to the IEA’s updated Net Zero Roadmap (2023), to reach net-zero energy sector CO2 emissions, over 70% of new energy capacity must come from wind and solar farms by 2050. But scaling up to meet this target is only half the battle. Ensuring wind and solar installations operate reliably across oceans, deserts, or mountains is just as critical.

Wind and solar farms are often built in some of the world’s harshest and most remote locations. Once installed, their components must function for decades with limited human access and under constant exposure to salt, sand, heat, and vibrations.

While most attention is focused on turbines and electrical panels, equally critical elements of system performance lie in the accessories that connect everything.

Like any high-performance system, such as long-haul aviation, offshore oil rigs, or space exploration, solar and wind systems demand components that are robust, modular, and remotely diagnosable. In a utility-scale wind or solar energy farm, a single weak link can compromise system integrity and interrupt power delivery. Which is why the industry is shifting from passive, one-size-fits-all accessories to tailored, intelligent component systems that anticipate downtime risks, extend infrastructure lifespan, and reduce overall operating costs.

The 5 grid accessory innovations leading this shift are: modular 145kV connectors for offshore wind farms, pre-assembled cable systems for grid electrical systems, sensor-based components, modular cable kits, and high-performance polymers and sealing materials.

Five accessory innovations redefining reliability in wind and solar energy farms.

1. Offshore-ready connectors engineered for high-voltage resilience

Offshore wind farms face unique conditions: constant motion, salt-laden air, and high-voltage transmission requirements. Conventional connectors can corrode, loosen, or degrade over time.

The innovation: Compact, modular 145 kV connectors designed for offshore wind applications are enabling more efficient transmission from increasingly powerful turbines. Their compact design facilitates installation in constrained environments while minimizing bending forces on connected equipment such as switchgear or transformers. Engineered for long-term performance, they feature high resistance to corrosion, vibration, and pressure, making them well-suited for the harsh and demanding conditions of subsea and offshore environments.

The result: Fewer failure points, longer service intervals, and enhanced safety in locations where unplanned repairs are difficult and expensive.

2. Pre-connected cable systems that minimize human error

In remote or high-risk locations, every hour spent on electrical installation increases exposure and cost. Grid technicians often face high levels of fatigue, while installation errors such as overtightening or misalignment can compromise long-term performance.

The innovation: Factory-assembled, tested and pre-connected cable systems minimize on-site handling, which helps reduce human error and accelerate installation in challenging environments.

The result: Safer, faster installations and greater reliability from day one, especially important in demanding environments.

3. Sensorized accessories that detect failure before it happens

Failure in a joint or termination often begins invisibly due to exposure to thermal fatigue, mechanical stress, vibrations, and moisture ingress. In remote wind and solar farms, these silent failures can go undetected until a power outage occurs.

The innovation: Accessories equipped with built-in sensors that continuously monitor internal conditions such as temperature and insulation health. The sensor-generated data is directly integrated with Supervisory Control and Data Acquisition (SCADA) systems and predictive operation and maintenance (O&M) schedules, enabling smart monitoring and intelligent diagnostics. Ørsted, the global leader in offshore wind and one of the world’s largest renewable energy companies, integrates cable diagnostics and performance monitoring into its offshore substations to support early fault detection and reduce unplanned downtime.

The result: Issues are detected early, enabling preventive maintenance instead of reactive repairs. This significantly reduces downtime and helps operators move toward fully digital, condition-based asset management.

4. Modular connector kits adapted to site-specific layouts

Each solar and wind farm configuration is unique.  Varying terrain, layout constraints, and project scale all affect how cable accessories are planned and installed.

The innovation: Modular connector kits tailored to site-specific layouts are now helping reduce errors and delays on large renewable projects. Each wind or solar farm comes with its own constraints (terrain variations, equipment spacing, layout geometry)—which can complicate on-site installation. To streamline this process, system modeling tools are used upstream to configure customized kits of pre-assembled connectors, adapted to the physical layout and routing paths of each site.

The result: This modular approach, inspired by practices used in offshore wind and utility-scale solar projects, ensures faster, safer, and more reliable installations, especially in remote or hard-to-access environments where technician time is limited and rework is costly.

5. Materials that resist decades of environmental stress

UV exposure, salt spray, sand, moisture ingress, hot ambient temperature and thermal cycling are harsh realities for wind and solar installations.

The innovation: High-performance polymers (such as EPDM Material) and sealing materials that resist abrasion, extreme temperature variations, and long-term weathering. These components are engineered to maintain integrity under the toughest environmental conditions, whether buried, exposed, or submerged.

The result: Accessories that withstand years of exposure without degradation, helping ensure system stability over time. Offshore wind developers now utilize vibration-tolerant junction systems to extend the lifespan of accessories in one of the harshest operating environments. As renewable infrastructure expands into increasingly extreme terrain and climate zones, long-lasting materials are proving crucial to performance and return on investment.

Innovative accessory technologies for a more resilient wind and solar energy future

As wind and solar energy take center stage in the global energy mix, connecting accessories must evolve to meet the demand for robust components that are adapted to extreme environments. Innovative accessory technologies are transforming once-passive components into intelligent, tailored, and long-lasting solutions that improve the system-wide reliability and cost-effectiveness of large-scale wind and solar farms.

Smart accessories, equipped with embedded diagnostics, connected to SCADA systems, and optimized through system modeling, are helping operators meet performance expectations while managing costs and risks.

In decentralized energy systems, even the smallest components bear the greatest responsibility. Nexans is at the forefront of advancing accessory technologies that enable uninterrupted power and reinforce system reliability in demanding environments. By focusing on robust design, embedded intelligence, and configuration based on system modeling, Nexans ensures that these silent connections deliver consistent reliability, contributing to the resilience of solar and wind installations.

The next time you switch on the lights, take a moment to ask yourself where the electricity comes from. You may be surprised to find that the source is hundreds or even thousands of kilometers away.

As electrical grids span greater distances across sea and land and reach impressive water depths, electricity generation is becoming more renewable and more interconnected.

But that wasn’t always the case.

Without advancements in power cable technology, transportation of energy was limited. The farther electricity traveled along a cable, the greater the loss, which made the transition to renewable energy challenging.

Today, thanks to continued advances in high-voltage direct current (HVDC) cables, renewables are outpacing fossil fuels in the generation of electricity.

​​​​​HVDC: Powering the future of renewables

Renewable energy grids today – onshore and offshore – require transmission lines capable of transmitting larger amounts of power over longer distances, more efficiently (lower energy loss), at greater sea depths, and able to withstand harsh environmental conditions.

And it is a key driver in the industry’s shift to 525 kV XLPE HVDC (high-voltage direct current) cable technology for large renewable projects – especially commercial offshore wind farms.

The transition to renewable energy requires a new approach to balancing demand and supply of power. Today, the interconnection of neighboring grids is solving this problem. For example, the grid interconnection between Norway and Germany is a perfect example of balancing ​​complementary energy sources for better grid reliability.

HVDC systems make it all possible. In the future, hybrid interconnections and HVDC meshed grids between countries and offshore wind farms will be a reality.

While up-front investment costs and complexity may favor HVAC, the lower transmission loss levels, ultimate power flow control capability, and black start capability may favor the new HVDC alternative.

According to the January 2024 ENTSO-E report – Offshore Network Development Plans, European offshore network transmission infrastructure needs – 14% of the offshore renewables could be connected via dual-purpose hybrid infrastructure in Europe by 2050.

4 cutting-edge advancements in HVDC technologies

Now, let’s delve deeper into the heart of four innovations allowing long-distance connections.

Subsea 525 kV HVDC XLPE – breaking new boundaries in renewable energy

The viability of commercial renewable energy projects is reliant on robust and highly reliable 525 kV cable systems. Achieving this requires increasingly higher quality levels throughout the manufacturing and installation value chain. For cable suppliers, this has meant the expansion of manufacturing facilities, new extrusion towers, creating high-voltage labs, and building advanced cable-laying vessels.

This feat necessitates building upon existing high technology readiness level (TRL) processes and solutions and improving them. At Nexans, cable system know-how plays an integral role in expansion plans and steers the company’s quality control (OC). Examples include:

Achieving the world’s first SF₆-free accessories

In 2023, Nexans achieved the world’s first electrical Type Test on a 525 kV HVDC cable system with SF₆-free accessories. The main benefits of using SF₆-free high voltage accessories include:

• reduced environmental impact
• lower maintenance requirements
• improved reliability.

By eliminating the use of SF₆ gas, cable terminations reduce their potential greenhouse gas emission by 99% and contribute to a more sustainable power grid.

Reducing cost per megawatt

The transition to renewable energy relies on interconnected grids transmitting renewable energy across greater distances and at higher power flows. This will reduce the cost per megawatt (MW) and further advance the economic viability of large commercial projects, especially large interconnector projects.

For instance, the same transmission power could be increased in a single circuit rather than two at a lower voltage; dramatically reducing the CAPEX required for a project while having a positive sustainability impact by reducing the use of scarce materials.

Increasing cable voltage will also reduce energy wastage – the higher the transmission kV, the lower the cable conductor losses. Less energy lost to transmission means that remote renewable generation sites will be even more competitive in the future.

Power cables – the backbone of the transition to renewable energy

The transition to renewable energy is essential to reaching global climate targets. At the backbone of this transformation sits the HV power cable.

Advancements in HVDC systems capable of transmitting renewable energy at greater power levels with less loss per MW at greater distances will drive the economic viability of large-scale renewable energy projects, notably offshore wind.

Did you know that 80% of the total ocean space is too deep for conventional offshore wind farms?

As wind energy takes on a greater role in providing sustainable electricity to millions, harnessing stronger and more consistent winds found farther offshore is critical. In recent years, advancements in high-voltage (HV) dynamic cables, critical to transporting energy back to land, are opening up new opportunities for offshore commercial wind power.

Harnessing wind power in areas previously impossible

A vast, untapped potential lies in harnessing offshore wind power. Although fixed-bottom wind projects currently lead offshore generation, nearly 80% of the world’s offshore wind potential is in waters deeper than 60 meters. This offers a tremendous challenge for the electrical transmission industry.

Yet, during the past thirty years, offshore wind has played an essential role in the decarbonization of energy. According to McKinsey, the growth of offshore wind capacity is projected to reach 630 gigawatts (GW) by 2050, up from 40 GW in 2020.

Since deeper waters are common along most coastlines worldwide, floating offshore wind turbines are crucial for these regions to harness offshore wind energy. Thus, floating offshore wind offers many countries and regions a viable path to electricity decarbonization. But getting this energy back to shore requires robust HV dynamic cables that can withstand the harsh conditions of the seas.

From sea to shore: How tech breakthroughs are powering up floating wind farms

One of the many advantages of placing wind turbines further out from the shoreline is the sheer power of the winds. More powerful and consistent wind speeds equate to a more reliable energy source.

Turning this powerful wind into sustainable energy is possible in part due to new developments in HV dynamic cables and enhancements in floating wind turbines and substation designs.

And it is thanks to these advances that by the end of the decade, large-scale floating wind farms on the West Coast of the United States, France, and South Korea will finally be a reality.

And we’re already seeing this happen. The first commercial floating wind project to be awarded is in France, off the coast of Southern Brittany. This monumental project will, upon completion, be the largest floating offshore wind farm in the world. The 250 MW site will double Europe’s current floating offshore wind capacity.

However, reaching this milestone requires getting the energy back to land where it can be transmitted and used. And this is where HV dynamic export cables are the critical link. To do that requires cables that can withstand deep-water seas. A feat that has taken years to achieve!

Overcoming new challenges going forward

The oil & gas industry has a long history of using medium voltage (MV) electrical subsea equipment. Today, that same philosophy is being explored for subsea substations. However, HV systems are a different playing field!

Transitioning to HV subsea equipment brings in a lot of additional challenges due to both increased voltage and larger sizes. This generates new challenges for design and handling offshore, combined with even more strict requirements for design tolerances and water tightness.

All HV subsea systems, including cables and potential substations and their connectors, require significant testing and qualification efforts over long time spans. Often, new failure modes arise as we acquire more knowledge about higher-voltage subsea equipment.

When it is possible to install subsea offshore substations or converter stations on the seabed, it will be a game-changer. It will unlock vast new areas for wind energy production, improve efficiency, and contribute significantly to the transition towards a sustainable energy future. For example, this advancement will significantly enhance the cost efficiency of electrical export, ultimately reducing costs and optimizing resources.

Growth of floating wind farms in the years to come

The vast open seas hold great potential in the world’s quest to decarbonize electricity. Floating wind farms, farther out and deeper, will play an increasingly important role in the battle against climate change.

Major advancements in HV dynamic capabilities play a critical role in achieving the commercial success of floating wind farms. Nexans’ groundbreaking 145 kV dynamic cable capable at 1300 meters opens up new opportunities for deep sea projects in harsh water conditions. This innovation is crucial for the future of commercial floating wind farms.

According to an August 2023 Global Wind Energy Council (GWEC) report, the floating wind market will accelerate by the end of the 2020s, with 11 gigawatts (GW) installed by 2030 and 26 GW by 2032.

Starting in 2031, floating wind installations will constitute over 10% of annual offshore wind installations, a notable achievement given the rapid expansion of offshore wind overall.

This growth will significantly contribute to adding decarbonized electricity generation to power grids, supporting global efforts to reduce carbon emissions, and the transition to sustainable energy sources.

Power grids are undergoing a monumental transformation. Driven by the energy transition, vast offshore wind farms are sprouting across the globe, promising a more sustainable future.

Connecting these remote parks to the mainland grid requires a crucial but often overlooked hero: the submarine power cable.

Imagine these cables as the silent arteries of the energy sector, carrying enough electricity to light entire cities. Their importance is undeniable – a single high-voltage cable tripping can put energy security at risk.

These underwater giants, stretching for hundreds of kilometers, face a unique set of challenges. Unlike their above-ground counterparts, they’re largely hidden from view, making proactive maintenance a critical and complex task.

Yet, recently, a declaration announcement emanating from six North Sea countries and NATO has emphasized the significance of infrastructure security and robustness.

This is where cable monitoring comes into play.

Monitoring of subsea cables: 3 main challenges

Due to the increasing reliance on offshore power sources, grid operators are being faced with changes and challenges. Here’s a closer look at some of the key concerns:

1. The end of a decentralized past

Traditionally, cable health data was scattered across individual local control rooms and equipment, making it nearly impossible to get a holistic view of the system. It was like having ten different doctors analyzing your health, each with their own reports and interpretations.

Thankfully, the tide is turning. We’re witnessing a shift towards centralized platforms that consolidate data from various sources, offering a comprehensive view and enabling faster, more informed decision-making.

2. The data deluge: Making sense of the noise

But the journey to a truly robust monitoring system isn’t without its obstacles. One major hurdle is the sheer volume of data generated by an array of sensors. Imagine being bombarded with continuous data streams from a thousand sensors – how do you identify a subtle change that can lead to a threatening event?

Another hurdle arises from the fragmented nature of the monitoring landscape. Different vendors often use proprietary technologies, making it difficult to integrate data from various monitoring systems. This creates a tangled web of information, hindering efficient analysis. The ideal solution lies in open platforms that seamlessly integrate with diverse monitoring technologies, providing a unified view of cable health.

3. The limitations imposed by longer interconnections

Subsea interconnectors, the power cables linking distant grids across vast stretches of ocean, pose a unique challenge for traditional monitoring techniques.

Take, for instance, the ambitious Great Sea Interconnector project, a planned high-voltage cable stretching a staggering 900 kilometers to connect the power grids of Greece and Cyprus.

At such immense distances, conventional monitoring methods using optical fibers suffer from signal attenuation – essentially, the message gets weaker as it travels, making it harder to detect issues.

To overcome this challenge, the integration of technologies akin to those used in transoceanic cables, such as amplifiers, is essential. Amplifiers can boost the signal strength at regular intervals along the cable, ensuring that monitoring systems maintain accurate and reliable communication.

5 advanced techniques for subsea cables monitoring

Thankfully, the world of cable engineering can count on plenty of solutions. Here are some of the cutting-edge technologies playing a vital role in safeguarding the health of subsea power cables.

Monitoring and the revolution of artificial intelligence (AI)

Of course, AI is among the most promising revolutions for the monitoring of subsea cables.

Indeed, the sheer volume of data generated by advanced monitoring systems can be overwhelming. This is where AI steps in, helping to:

• Filter Out Noise and Identify Threats: By analyzing complex data patterns, AI can effectively distinguish between background noise and real threats. This ensures that operators focus their attention on the most critical issues.
• Predictive Analytics: AI can leverage historical data and real-time sensor readings to assist in identifying potential problems before they even occur. This allows for preventative maintenance and minimizes downtime.

The road ahead: Monitoring powered by constant innovation

Imagine a user-friendly cockpit that displays real-time data, analyzing failure modes, and proposing remediation actions for all your cable assets in single place: this, in essence, is the future of cable monitoring.

Comprehensive cable monitoring solutions are paramount. A centralized approach not only simplifies cable management but also empowers operators to make informed decisions quickly and efficiently.

Nexans, at the forefront of these innovations, has developed a solution that isn’t just an abstraction layer: it is a versatile data platform, with state-of-the-art digital frameworks, intuitive dashboard and harmonized analytics that brings the cable data management to the next level. It integrates information from various sources and presents a clear picture of the network’s health.

Built to scale, it adapts seamlessly to the growth of the grid. Whether through on-premise deployment or cloud-based access, this solution offers flexible options. Prioritizing cybersecurity, the platform utilizes the latest technologies and maintenance processes to safeguard critical data.

The energy transition depends on the silent guardians of the grid – subsea power cables. As we harness the power of offshore wind farms, robust cable monitoring becomes an indispensable tool. By overcoming the challenges of data management, signal interpretation, and technological fragmentation, we can ensure the health and longevity of these critical underwater connections.

Innovative monitoring technologies can help the silent heroes under the sea to continue to play a vital role, ensuring the lights stay on and our cities vibrate with sustainable energy.

Electrification, particularly from renewable sources, is playing a pivotal role in the world’s quest for net zero emissions. And as we move towards a more electrified future, it’s crucial to acknowledge the environmental impact of the very cables that power our lives.

The demand for subsea cables that can safely and efficiently carry the growing current is surging. As innovative technologies are reaching new heights in their ability to transmit sustainable energy at greater volumes, distances, and depths, ensuring their sustainability throughout their life cycle is equally important.

Let’s dive into the innovations in electrical transmission that are unquestionably promoting this shift.

Subsea cables: the need for a sustainable mindset

But first, there are two reasons why the question needs to be raised.

1. Cables’ components

The environmental footprint of the cables’ materials demands our attention. These are the obvious environmental costs it takes to electrify the future.

Above all, the conductor, which channels the electrical flow, is composed of copper or aluminum and constitutes a significant part of the overall GHG emissions of subsea cables. Much of this is due to the energy required in producing and purifying the metals, which is why it is essential to use renewable energy in the extraction process to reduce the environmental impact.

2. The importance of sustainability in a resource-constrained world

Did you know electrical wire and cable can contain up to 80% copper?

Known as ‘the metal of electrification,’ copper is paramount in the production of cables. The metal is excellent for conducting electricity efficiently: its unique properties allow for a smooth flow of electrons, which minimizes energy loss in transmission lines.

Yet, due to the growing focus on electrification, global copper demand is expected to reach 39 million tons in 2030 (compared with 13 million tons in 1995 and 29 million tons in 2020). And possibly, at the same time, it might become increasingly scarce. Furthermore: its excavation and mining come with its own social and environmental challenges. Co-existence with other industries such as fisheries as well as local communities which might be adversely affected by mining can limit access to potential resources.

Let’s now explore the solutions and innovations that are key to help us mitigate the environmental impact of subsea cables.

The future – moving to a sustainable mindset

Nexans positions itself at the forefront of this impetus. For example, the Group’s casting facilities in Canada, France, and Peru reused roughly 19,700 metric tons of copper scrap in 2022. In 2008, Nexans and Suez formed the joint venture RecyCâbles as a complete cable recycling solution. Since its inception, it has become a European leader for cable recycling and recovery.

Here are three concrete examples of current innovations that are leading the way:

SF₆ replacement and GIS terminations

Replacing SF₆ as insulating medium in cable terminations, with alternative insulating gases (such as GE’s g³) or with dry-type solutions, is critical. This would reduce the GWP, with more than 99 percent, in any event of accidental gas emission. Converter manufacturers are also currently developing switchgears using alternative gas to SF₆, so this gas can be substituted in the complete HVDC cable systems.

The advantage of using GIS terminations is twofold, because GIS terminations also allow a major reduction of space needed in the offshore converter stations, which leads to significant reduction of converter platform size, and consequently of steel used for its construction.

The OceanGrid Project

Innovative research initiatives are instrumental in seeking more sustainable and viable interconnectors. With the OceanGrid Project, research is being carried out on a new aluminum alloy aiming to advance the deployment of profitable offshore wind farms in Norway in 2030 – 2050.

The AluGreen consortium

In the AluGreen consortium, Nexans leads the exploration of introducing end-of life conductor materials in new subsea cables. The consortium draws from the full aluminum value chain in Norway which sets the stage for piloting full circular business models.

The world is electrifying, and the cables that carry this energy surge need a sustainable upgrade.

Subsea cables are crucial for efficient transmission of renewable energy offshore. Yet, they can have a significant environmental footprint.

Traditional materials and production methods create challenges; however, innovation, from recycling to new technologies, is paving the way for a more sustainable future.

Imagine a giant sea serpent made of copper and steel, winding along at a depth of 3,000 meters under the sea. No, it’s not a mythical sea creature, it’s an interconnector cable!

You are no doubt already familiar with subsea fiber optic cables, the technology making it possible for you to read this article. Yet the underwater depths also host far larger cables, able to transmit electricity from one country to another.

What is an interconnector?

Routed under the sea, these high-voltage cables play the role of invisible highways, taking electricity from one country to another.

They measure up to 300 mm in diameter and can weigh up to 140 kg per meter… for a total weight of up to 9,000 metric tons! We’re talking here about gigantic structures that can weigh as much as the Eiffel Tower.

To imagine what’s inside, think of a big sushi: the cable body is made of copper and sometimes optical fiber, protected by an armor of thick steel.

These subsea cables are manufactured in ultra-modern plants, able to assemble the various components with millimetric precision. They are then transported on cable-laying vessels, which deploy them on the seabed.

This operation is a real technological feat, making it possible to transfer power across seas and oceans, in order to support the energy transition.

What are the advantages of subsea interconnectors?

Let’s just take a step back in time: the first interconnections between national power grids took place two decades after World War Two.

Today, Europe is the most advanced continent in terms of interconnections. Its highly sophisticated network relies in part on these subsea cables.

A fast-growing interconnection market

It is no surprise to see the offshore wind and interconnection markets expanding at a rapid pace. Major investments will be needed wherever the level of interconnection remains insufficient.

Subsea cables are becoming an increasingly common choice, not only in America and Europe, but also elsewhere in the world. In September 2023, for example, the grid operators of Greece and Saudi Arabia signed a strategic agreement setting up ‘Saudi Greek Interconnection”, a joint venture to link their power grids.

So, in short… Subsea interconnection cables are invisible giants, energy highways winding along the seabed.

As such, they have a crucial role to play in the global energy transition: enabling the exchange of electricity between countries, promoting the integration of renewable energies, securing supplies and contributing to lower prices.

These cables represent both a technological feat and a colossal level of investment. Their development is part of an ongoing dynamic. Subsea cables are a key part of efforts to address climate change and to build a more sustainable energy future.

Renewable sources of electricity become an increasing and exceedingly important factor in the energy equation. Global annual renewable capacity additions increased by almost 50% to nearly 510 gigawatts (GW) in 2023, the fastest growth rate in the past two decades, marking a major step forward in the reduction of fossil fuel power. Moving to renewable energy is vital to decreasing greenhouse gas emissions and aligning with the 1.5 Celsius climate target set in the Paris Agreement.

Even as renewable energy generated a record 30% of global electricity in 2023, furthering the growth of renewable energy relies heavily on grid interconnection.

Interconnections provide the optimal way to ensure energy security across regions and continents:

• When grids are interconnected, surplus energy from one region is easily transported- via the interconnected power grid – to where electricity is needed. This ensures energy security across the interconnected grids and avoids reliance on fossil fuels when renewable energy cannot meet local demand.
• By equalizing demand and supply across interconnected grids, excess power is more readily available to areas with increased demand, thus ensuring energy price stability and future renewable investments.
• The harnessing of electricity across grids goes beyond adjacent regions to include the interlinking of power grids across continents and islands and offshore renewable energy sources. Deep water, once a barrier to interlinking grids, is less of an issue thanks to innovations in cable design, new materials and alloys, and cable installation and maintenance advancements.

1. Deep sea grid interconnections – from megawatts to gigawatts

The interconnection of grids is not only reaching impressive depths, but their capacity has also gone from hundreds of megawatts to gigawatts.

To date, the deepest installed HV cable system is the SaPeI interconnector, stretching 435 kilometers, linking Sardinia and mainland Italy, reaching 1,640 meters below sea level.

One revealing example of this revolution is the Tyrrhenian Links project, currently under construction. It will connect Sicily with Sardinia and the Italian peninsula. It will be installed at a record-breaking 2,200 meters deep, for a transmission capacity of 1,000 MW. Achieving this is possible thanks to advances in high-voltage direct current (HVDC) systems, which can transmit larger amounts of power over long distances.

If this technology is already available for shallow waters, engineering challenges arise when increasing the water depth.

2. Mass-Impregnated (MI) undersea cables – decades-long reliability track record

Mass-impregnated cables’ first commercial use was in 1954 for the Gotland HVDC Link to connect the Island of Gotland to mainland Sweden. Since then, mass-impregnated cables have been the primary choice for subsea HVDC interconnector projects requiring voltages surpassing 500 kV over long distances and extreme depths.

Simply put, a MI undersea cable is a type of HVDC cable specifically designed for underwater applications. Here is the breakdown:

• Construction: it is made with layers of high-density paper tapes wrapped around the conductor. These tapes are then impregnated with a special, high-viscosity compound. This compound is key – it’s thick and doesn’t flow easily, even if the cable is damaged.
• Application: it is used for transmitting large amounts of electrical power over long distances underwater. They are particularly useful for applications exceeding 500 kV DC and long distances.

MI cables offer three main advantages that make them innovative for undersea applications:

1. Reliability: The high viscosity compound prevents leakage even if the cable is damaged, making it more reliable for underwater use compared to older designs.
2. Durability: cables installed decades ago are still operational today, demonstrating their long lifespan.
3. Depth capability: they can be used for extreme depths with proper design features.

Overall, MI cables are a well-established and trusted technology for transmitting large amounts of power underwater, making them a key innovation for subsea power transmission.

Breaking even new barriers to deep sea cable depths will be the Great Sea Interconnector project. Reaching depths of up to 3,000 meters in some areas, the project will connect Israel, Cyprus, and Greece via Crete. Stretching 900 kilometers from Crete to Cyprus, the 1,000-megawatt, bi-pole cable will bolster energy security and facilitate electricity exchange between the countries.

3. Overcoming subsea cable challenges – new design approaches

The main challenge in using MI technology in subsea cables however is the elongation of the insulation system during deployment and retrieval.

There are many ways this can be overcome. The most prominent is through cable design, conductors, materials, or installation methods.

Additionally, 500+ kV extruded cable designs are also being developed. A major advantage of extruded cable design is its ability to sustain greater elongation compared to MI cables. A challenge for extruded design is the need for effective water blocking in the conductor in the case of damage to the cable. At 3,000 meters below sea level, the pressure is so great that if the water is not blocked in the conductor, it can easily penetrate tens of kilometers into the cable, leading to costly repairs.

Nexans is deeply involved in the electrical transmission revolution that is going on.

In fact, the Group has been playing an essential role for a long time. In 1977, Nexans deployed its first HVDC MI cables for the Skagerrak subsea interconnector between Denmark and Norway. Almost 50 years later, the original cable system is still in use. Today, its expertise in building, installing, and repairing deep sea HVDC systems spans MI and extruded technologies.

Its most monumental undertaking is currently crafting the world’s longest and deepest subsea interconnection: The Great Sea Interconnector. This colossal project symbolizes a new era in energy interconnections and demanded immense resources and logistical mastery.

Innovation is the lifeblood of deep sea grids. For this sustainable future revolution to reach its full potential, robust and far-reaching interconnectivity is paramount. Deep sea grid interconnectors are the invisible threads weaving a global energy tapestry. Challenges remain, but solutions are on the horizon.

Deep sea grids are not simply cables on the ocean floor; they are the lifelines of a safer energy landscape. They are the physical manifestation of a global commitment to a sustainable future, a future powered by the boundless potential of renewable energy.

Faster, higher, stronger – together is the motto of the Olympics, but it can also apply to the changes happening in the electricity transmission and distribution industry.

As decarbonization of energy takes on a heightened importance globally, it will take a unified approach to reach net zero by 2050. To do so will mean eliminating fossil fuel combustion and transforming power grids to accommodate intermittent renewable energy.

Rejuvenation of the grid that a decarbonized and electrified world needs differs significantly from the ones built post World War II and on which we still rely today. Modernization and newer storage technologies are crucial in decarbonizing electricity. But equally important are the connections of supply from one electric network to another to ensure energy reliability and stability and transition the world to renewables.

Thus, according to a report published by the International Energy Agency, the world must add or replace about 80 million km of grids by 2040, equal to all grids globally today, in order for countries to meet their climate goals and to achieve energy security priorities. Considering only offshore wind in Europe, 48 000 to 54 000 km of HV cable route length shall be added by 2050 to meet the offshore wind targets of the European countries, according to a ENTSO-E’s TYNDP report published in January 2024.

For decades, experts have discussed interconnections. However, two crucial factors are now driving their escalating importance: the increasing availability of renewables and the vulnerability of today’s network to climate change.

Put simply, an interconnection links a network of grids together at a synchronized frequency. This enables the transfer of surplus energy from areas with excess power to those with higher demand than they can meet locally. Harnessing electricity from a regional grid allows the local network to reduce the risks of power outages or failures, thereby boosting power reliability and stability.

In addition, interconnection links islands and continents to sources where renewable energy generation is more plentiful, thus progressively diminishing reliance on fossil fuels. Examples include the interconnection between Crete to Greece, Mallorca to Spain and Tasmania to Australia. This enables the development of renewable energy sources on these islands, freeing them from dependence on polluting power generation.

Here are five innovations that will make electrical transmission reach new heights.

Interconnections globally are instrumental in ensuring the viability of sustainable energy and reducing the reliance on fossil fuels. Achieving this requires a cutting-edge mindset in designing, manufacturing, and installing deep-sea cables that can transmit increasingly higher energy levels and that can realize interconnexions in previously impossible areas.

Moreover, innovation in electrical transmission is unquestionably linked to unerring monitoring as well as highly sustainable design.

From the engineering, manufacturing, construction, and installation of HVDC cables for connection systems, to the world’s first electrical Type Test with 320 kV HVDC cable termination using GE’s g³ gas to considerably lessen global warming potential, by way of the increasing amount of recycled metals used in cables: Nexans is at the forefront of these innovations.

In the coming weeks, we invite you to deep dive into these innovations that will revolutionize the electrical transmission industry.

The race to net zero is on, and to cross the finish line by 2050 industry needs to shed the burden of fossil fuels. But which energy sources have the power to replace them?

Although electricity is the undisputed front-runner when it comes to cleaner energy alternatives, electrification falls short in parts of the world that are isolated or lack solid electrical infrastructure. And this is without mentioning all the “hard-to-abate” sectors such as steel industry or intensive mobilities.

That’s where hydrogen steps in. The gas is already used as a chemical reagent in industries such as oil refining and agrochemicals, to the extent of 90Mt a year. And now a boom is on the cards, with demand predicted to increase by a factor of 4 to 6 by 2050. Production from water electrolysis would then account for over a quarter of the global power demand!

Decarbonizing hydrogen

But just how virtuous is hydrogen? Its production processes vary wildly in their environmental impact, leading to the informal and sometimes bewildering hydrogen rainbow classification system. The vast majority of hydrogen today comes from fossil fuels via high temperature steam reforming of methane, with 10kg of CO2 emitted for every kilogram of H2. This type of production is responsible for 2-3% of global CO2 emissions, on a par with air-travel!

Making hydrogen is also possible using electrolysis. This process, that splits water molecules into oxygen and hydrogen, is energy-intensive – 50-60 kWh generates 1kg of hydrogen. But when the electrolyzers are connected to renewable energy sources, very low-carbon hydrogen can be achieved.

However, its low density at room temperature means it must be compressed at high pressures – up to 700 bar – or cooled to a very low temperature – -253°C (20K) – to turn it into a liquid that can be transported and stored.

Furthermore, the carbon intensity of hydrogen produced by water electrolysis depends on the energy mix of the electricity source. In some countries with lots of coal power plants, the carbon footprint of electrolysis process could be more detrimental than steam methane reforming.

High-pressure challenges

New applications for hydrogen are springing up in the fields of energy and mobility. But to ensure the boom doesn’t run out of gas, big changes must be made over the whole lifecycle.

This starts with production. For hydrogen to truly contribute to a net zero emission world, the energy used for the electrolysis must come from renewable sources such as onshore or offshore wind and solar farms which Nexans already connects. This will have a direct impact on hydrogen’s price tag, which will then be driven by the costs of electricity and capital investment in farms and electrolyzer units.

Once it has been produced, all this hydrogen still has to reach the end user, and the right storage and transportation solutions could mean the difference between success and failure. Just one kilogram of hydrogen takes up 12m³ at atmospheric pressure, and very high pressures (up to 700 bar) are needed to bring this volume down to manageable levels.

The solution? Liquefy hydrogen. This has been a practice in aerospace for decades, and new applications for liquefied hydrogen (LH2) are emerging, such as:

• Overseas transportation of energy between production and consumption places. The Hystra project – producing hydrogen in Australia and shipping it by cargo to Japan – was a world first, enabled by Nexans high-flexibility cryogenic transfer lines. Projects aiming at deploying the infrastructures for maritime transportation of LH2 are now starting in key maritime ports to prepare the forthcoming worldwide trade of LH2.
• Aeronautics. Airbus is aiming to fly the first commercial plane fueled with LH2 in 2035. This will mean a complete change of airport infrastructures to supply hydrogen, electricity and sustainable aviation fuels, in places where safety and floor space are major stakes.

Innovation at every stage of the game

Nexans is contributing new technology and business solutions all the way down the hydrogen value chain.

• On the production side, we provide solutions for optimizing the operating and capital expenses of producing renewable energy. Applied to electrolyzing units, our unique know-how on grid design could help achieving optimized hydrogen production facilities
• On the storage and distribution side, Nexans has long been a pioneer in supply infrastructures for cryogenic fluids. Our vacuum-insulated flexible transfer lines offer easy-to-install, safe and reliable solutions for tank-to-tank transfer of LH2. Their “plug-and-play” installation is as easy as laying a power cable and beats conventional rigid piping systems when it comes to speed of implementation. We recently equipped the world first loading systems for ship-to-shore transfer of LH2 in Kobe, Japan, with long length, high flexibility cryogenic transfer lines capable of high flow rates, numerous bending cycles and minimal boil-off.

The future is hybrid

If smartly combined, electrification and hydrogen will team up to contribute to more efficient low-carbon energy supplies. Pushing forward the complementarity between the two energy vectors, we are currently developing new concepts of hybrid lines able to vehiculate both hydrogen and electricity in the same system, including:

• Subsea umbilical systems to transfer hydrogen, data and electricity between offshore production units, such as wind farms or energy islands, and land;
• Superconducting systems combining LH2 transfer and superconductivity for hybrid energy highways that can transmit impressive amounts of power over long distances and help modernize power grids.

Ultimately the transition to net zero will require a shrewd combination of many interlocking energy sources and technologies. Together with electrification, Nexans is empowering hydrogen to become a safe, effective, economically and environmentally viable contributor to the energy supply of tomorrow.