A Carbon Trust-led offshore wind industry project is seeking to increase array voltage from 66kV to 132kV, to enable larger turbines and reduce offshore wind costs.
Increasing array voltage enables more efficient power collection at wind farms and also reduces the length of cables, reducing costs and minimising environmental impacts of building offshore wind electrical infrastructure.
The industry’s last voltage shift began in 2010, when the Offshore Wind Accelerator (OWA), which is the Carbon Trust’s flagship research, development and deployment programme, “drove the change” from 33kV to 66kV.
The OWA did this in collaboration with nine leading offshore wind developers, which resulted in 8-12MW turbines being installed and was considered a “key factor” in offshore wind’s success.
Since then, as the industry has grown rapidly in both wind farm and turbine size, it is anticipated that the next jump to 132kV will lead to significant cost savings, which will help the industry scale up to 250GW by 2030.
As an example, for a 1200MW wind farm, cost savings are predicted to be in the range of £32m to £50m relative to the equivalent 66kV system, stated OWA.
The 132kV conclusion was drawn from a recent project conducted by the OWA.
In 2020 the OWA prioritised the need to find a voltage that would accommodate the growing size of both turbines and wind farms, leading to the creation of the High Voltage Array Systems (Hi-VAS) project.
The partners are EnBW, Equinor, Ørsted, Ocean Winds, RWE, ScottishPower Renewables, Shell, SSE Renewables, TotalEnergies and Vattenfall.
The project was delivered by Carbon Trust, TNEI, Petrofac, Orient Cable and Hellenic Cables.
Hi-VAS engaged with over 70 different organisations, including suppliers, energy system operators, marine planners, policy makers and international regulators.
Building on the input received from these stakeholders, the project conducted a series of engineering studies to assess a range of possible future array voltages, and how they would impact wind farm design.
Of all the voltages considered, 132kV had the best cost-benefit ratio, and the lowest risk profile.
The conclusion of 132kV has been strength tested with the developer consortium and the wider industry stakeholder network and has received unanimous support.
The project found 132kV wind farms will be operational by the end of the 2020s at the earliest.
OWA said that even this timing is dependent on significant proactive work to be carried out by developers and supply chain.
Stephen Loft, electrical department manager at ScottishPower Renewables, said: “In order to provide cheaper green energy to everyone quicker, doubling the voltage of our wind farm cables is essential.
“The global offshore wind industry will benefit immensely from increasing the voltage to 132kV. Doing so will unlock cost savings by reducing cable lengths and reducing electrical losses.
“Further, it will enable the next generation of wind turbines to be brought to market, which will provide step-change cost savings for the industry.
“Reducing cable length offshore will also reduce the environmental footprint of offshore wind farms.”
Gonzalo Cuevas, senior electrical specialist at Ocean Winds, added: “The work done by the Hi-VAS group towards increasing to 132 kV as the next array voltage will unlock a whole new potential in the offshore wind industry, not only by accommodating the system for the next generation wind turbines, but also reducing the costs through innovation to achieve a carbon-neutral world.”