When it comes to wind turbines and winning the public relations charm offensive, offshore is definitely the way to go. The very nature of siting wind turbines out at sea ensures there are fewer objections from protesters, environmental pressure on the brownfield sites of Europe is considerably eased and, most importantly, higher and more constant wind speeds offshore mean higher efficiencies.
As with life generally, there is of course a price to pay for the advantages of building offshore wind farms and for every bonus there is a potential downside. Recent industry figures, for instance, point to potential spiralling repair and maintenance costs, particularly for Europe’s growing flotilla of offshore installations. The figures suggest some 600 turbines at 13 wind farms could be affected and may face repair bills estimated to be around the £25m mark. Nevertheless, the pioneers of the offshore wind industry did not take the business to the heights it has already achieved in renewables by being negative and with a little ingenuity and determination most of the hurdles facing offshore can be surmounted. So what are some of the major difficulties and what can the industry do to address them?
Design issues
Hundreds of European offshore wind turbines have a design fault allowing them to slide on their bases, it was reported in 2010. Finding a solution could take months and cost millions of pounds, European turbine makers and wind farm operators said at the time. The shortcoming involved wind towers using grouting, a mixture of cement, sand and gravel to attach the turbines to their base, they told the Reuters news agency. In some cases the main superstructure of the wind towers had moved several centimetres on their base after the initial installation.
Experts recommended the monitoring of any movement and the use of steel blocks on the T-piece brackets to support the structure. Meanwhile, the grout, which was initially classified with a safety factory of three has been reclassified for this type of design to one or below – with the proviso that the larger the design, the less safe it is. As for costs, Scottish & Southern has quoted £4 to 5 million for the 140 turbines at Greater Gabbard, should they require a retrofit.
