Following an international competition the Carbon Trust’s Offshore Wind Accelerator (OWA) has awarded contracts to three cable manufacturers to help commercialise the development of 66kV offshore wind farm intra-array cables. It is providing funding of £400k (£133k to each cable manufacturer) to accelerate the time to market of the cables for use in the large scale UK Round 3 offshore wind farms. Testing of two of the new cable designs is due to be completed as early as the end of 2015.
The OWA identified the potential for higher voltage electrical arrays to deliver significant cost benefits to the design of future offshore wind farms. It was found that moving to 66kV can demonstrate a material improvement in lifecycle costs compared with 33kV. Moving to the higher voltage becomes even more attractive as wind turbines continue to increase in size – and it should also allow intra-array cable lengths to be reduced.
The Carbon Trust has calculated that a move to 66kV cables could cut the cost of offshore wind energy by 1.5% which equates to a Round 3 cost of energy saving by up to £100m per year. Cost saving benefits of 66kV will be achieved through increasing the availability of turbines by optimising the intra array cable layout of offshore wind farms.
Megan Smith (Electrical Systems Project Manager, Offshore Wind Accelerator) said:
‘Moving to 66kV intra-array networks offers a great opportunity to cut costs in time for Round 3 offshore wind farms. But the industry faced a classic chicken and egg problem. Cable manufacturers were unwilling to invest in the certification process of a new cost effective 66kV cable without knowing if there is demand, and developers can’t specify a new array cable voltage when cables are not yet certified. The Carbon Trust’s OWA has resolved this by enabling the cable industry to work with the offshore wind sector to develop a solution that will benefit all.”
The Carbon Trust has awarded funding to the three cable manufacturers to qualify 3 different cost effective cable designs, as well as share the results from the qualification of a fourth cable. These are:
– JDR: will qualify a 3-core 630mm2, copper conductor, wet design, 66kV cable,
– Nexans: will qualify a 3-core 630mm2 aluminium conductor, dry design, 66kV cable, as well as share findings from their qualification of a 3-core 630mm2, copper conductor, dry design, 66kV cable,
– Prysmian: will qualify a 3-core 800mm2, aluminium conductor, 66kV cable.
Test results from all four cables will be available in 2015, with extended test programmes for some cable prototypes expected to be complete by 2017.