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.
But first, there are two reasons why the question needs to be raised.
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.
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.
To overcome the scarcity of copper, aluminum is increasingly being applied in subsea cables. Generally less expensive, its usage can substantially reduce costs. Above all, its source, bauxite is far more abundant, albeit it also comes with similar co-existence challenges as copper mining.
Current breakthroughs in the aluminum smelting process are reducing carbon dioxide emissions. For example, ELYSISTM, a technology partnership of industry pioneers Alcoa and Rio Tinto, eliminates direct greenhouse gas emissions from the carbon anode used in its electrolysis process, emitting oxygen as a byproduct.
By leveraging an increasing amount of recycled metals in the production of cables, their environmental impact is significantly reduced.
Let’s start with copper:
Same thing for aluminum:
The source of the recycled metals also matters. Two types of materials can be distinguished:
Of equal importance is sourcing metals from suppliers that adhere to responsible practices. Initiatives such as the Copper Mark provide a framework for responsible production, sourcing, and recycling of copper.
Producing cables also requires the use of plastics. Incredibly versatile, strong, lightweight and affordable to produce, they are the go-to choice for countless industries.
That is why recovery of plastic waste, including PE, is of growing importance.
Sulfur hexafluoride (SF₆), an insulating medium in switchgear, is also a major concern due to its high global warming potential (GWP).
Hopefully, a transition of plastic materials is possible:
Through improved recycling and thoughtful design, a circular economy makes plastic waste from cables minimized and its environmental impact significantly reduced.
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:
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.
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.
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.
Audun Johanson is an R&D Project Manager & New Opportunities in Nexans’ Generation & Transmission Business Group, where he drives technology development for future energy transmission with a particular focus on floating wind and circularity.
He has joined Nexans 10 years ago with an educational background in material science from the Norwegian University of Science and Technology, Norway.
Nils-Bertil Frisk is the Discipline Responsible for HVDC Extruded Accessories in Nexans’ Generation & Transmission Business Group, where he has the responsibility to develop, maintain and standardize HVDC Extruded cable accessory portfolio.
Nils-Bertil started in Nexans R&D department 10 years ago with a main focus on HVDC Extruded accessories.
Nils-Bertil has a Master’s degree in Electrical Power Engineering awarded from Chalmers University of Technology, Sweden.
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