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Harnessing the winds of change
These are testing times for the energy sector. The Covid-19 pandemic has hit hard, bringing with it supply chain disruption, plummeting energy demand and questions over long-term financing.
The economic headwinds are real. Yet there is still room for optimism, particularly when it comes to renewables. Offshore wind is a case in point. This remains one of the world’s fastest growing industries (Source: Global Wind Energy Council, May 2020) and it could play a vital role in post-crisis recovery – providing governments with an opportunity to pursue economic stimulus and Green Deal goals at the same time.
More about wind energy on GWEC:
Driving down costs
One factor that makes the offshore wind sector attractive is its track record of innovation. Despite the relative newness of the sector – utility-scale offshore wind is less than 20 years old – it has made massive strides in terms of efficiency. Costs have fallen dramatically.
To put this in context, both offshore and onshore wind costs have dropped by more than 50% on average over the past five years. The cost of offshore fell by nearly a third between 2018 and 2019 alone, research by Bloomberg New Energy Finance shows. (Source: Global Wind Report 2019 - Global Wind Energy Council).
So how are these savings being achieved? And what innovations can be expected in the future?
Related information on wind energy:
“ One factor that makes the offshore wind sector attractive is its track record of innovation. ”
Taller towers, bigger blades
Bigger is always better in the world of power engineering: the laws of physics dictate that large machines are always more efficient than small ones. In the case of wind turbines, larger rotors with longer, lighter blades allow greater energy capture, even at relatively low wind speeds.
Towers are getting taller. Wind speed increases with height, so higher towers allow rotors to tap into stronger and more consistent airflows – reducing intermittency. Currently, the tallest turbine is 260m and capable of generating 12MW – enough to power around 16,000 homes. Turbines with a capacity of 15MW are expected by the mid-2030s.
Bigger turbines are not only more efficient at generating electricity, but are also more cost effective to deploy. Fewer turbines are required, so installation and maintenance costs are lower. Together, these factors contribute to a low levelised cost of energy.
technical potential of global offshore wind (*source: IEA Offshore wind outlook)
potential jobs in wind energy by 2030 (*GWEC statement - April 2020)
One of the big challenges with offshore wind is building foundations for turbine towers. The conventional method is to fix the structure directly to the seabed. A number of approaches are adopted. These range from relatively simple monopile foundations, suitable in shallow waters, to complex jacket foundations for depths over 30m.
The problem with conventional foundations is that they are not economically viable in deep water. This matters because most of Europe’s wind resource – 80% of it – occurs over waters that are 60m deep or more.
The answer could be floating offshore wind. Floating turbines do not require conventional foundations. Instead, turbines stand on a floating substructure that is tethered to the seabed with mooring lines and anchors.
The technology is proven: the world’s first commercial floating wind farm, Hywind Scotland, has been in operation since 2017. The beauty of floating turbines is that they allow developers to tap into stronger and more consistent winds further out to sea, transforming the economics of offshore wind.
As wind farms grow in size and are built further out to sea, new approaches to cabling are needed. Electrical resistance is a key constraint: in order to overcome transmission losses, the current must be kept to the minimum. This means that high-voltage transmission is required.
The trend towards higher export voltages is already established with 220kV AC increasingly the standard. However, limitations inherent in AC transmission mean that high-voltage DC systems are becoming more prevalent for long-distance export.
Both AC and DC export solutions use conventional cabling, so high voltages are essential. But what if you could export electricity without the need to step up the voltage?
Superconducting cables could hold the key. Unlike conventional copper and aluminium cables, superconducting cables offer no resistance. This means they can handle extremely high currents at medium voltage. As well as eliminating resistive losses, superconductors have the potential to reduce the amount of equipment and maintenance needed offshore.
Innovations like these hold the key to enabling the energy infrastructure of the future – and to providing clean, cost-effective electricity for decades to come.
Nexans solutions and services are designed to drive down costs and accelerate the deployment of offshore wind. Our innovative WINDLINK® cable harnesses for wind turbines are an example. These plug-and-play kits make turbine installation quick and easy – and provide years of reliable service. That’s why Nexans is a preferred supplier to the offshore wind industry, with customers including Iberdrola, Ørsted, Siemens Gamesa and Vestas
Nexans is present throughout the offshore value chain with a complete offer that includes advanced submarine cabling systems, accessories and services from design engineering to maintenance. And in 2021, we’re launching CLV Nexans Aurora, the world’s most advanced cable laying vessel – underlining our commitment to helping our customers achieve their biggest ambitions.