Electricity has started flowing from the Hornsea 2 wind farm, which will become the world's largest offshore wind farm when it is complete. Located off the UK's east coast, it's unlikely to hold the title long, however. The expansion of onshore wind has flattened out, but offshore is very much in the exponential growth phase, and some immense projects are under development and consideration. China's largest offshore wind farm reached full operation a day later.
When complete, Hornsea 2 will consist of 165 Siemens Gamesa wind turbines, each with a peak capacity of 8 MW. Many of those turbines are still to be installed, but the offshore substation and associated equipment for smoothing fluctuations were completed in October, and shortly before Christmas developer Ørsted announced power had started to flow from the first turbines.
The timing is fortuitous. The possibility that limitations in gas supply could, in combination with a cold winter, cause serious disruptions to electricity networks in the UK and northern Europe has caused anxiety for months. Even a fraction of Hornsea's eventual production will help buffer against that danger. On its first morning, it contributed to wind power providing almost 50 percent of Britain's electricity.
At 1,320 MW (equal to 1.3 million typical UK homes) Hornsea 2 will take the title of world's largest from the neighboring Hornsea 1, which has smaller but more numerous turbines, for a total capacity of 1,218 MW.
The development coincides with China's largest offshore wind farm, Jiangsu Qidong, being connected to the grid at full capacity on Christmas Day. At a total of 802 MW, Jiangsu Qidong is behind either Hornsea stage, but it is twice the size of the next largest existing offshore wind farm outside northern Europe. Where European and North American wind farms usually standardize by using a single size and make of turbine to save costs, Jiangsu Qidong has gone in the opposite direction, using seven models from four manufacturers.
Neither Hornsea nor Jiangsu Qidong remotely compares to the giant wind farms being developed by Denmark and South Korea, and the more speculative giant off Iceland. Even before those come to fruition, Hornsea's third stage – with 2,400 MW soon to start construction – will leave them well behind.
Even with operations beginning at these wind farms, offshore wind accounts for less than 10 percent of global wind production. It's also currently more expensive. However, prices are falling faster for offshore, as turbines get larger and experience grows, than for wind developments on land. It is anticipated the next round of UK wind farms, instead of requiring subsidies, will return money to the public. Moreover, with rare exceptions, winds are steadier offshore than on, reducing the intermittency that is now wind's last major disadvantage compared to fossil fuels. In some locations, offshore wind also peaks at different times from onshore, so a mix of the two complements each other.