InvestigationThe European offshore champion wants to quintuple its capacity within a decade. But the intermittency of this renewable energy complicates the situation.
Arriving nearby, the gigantism of the mechanics being prepared suddenly becomes evident. An 81-meter blade is stretched along the factory, while employees who appear microscopic beside it prepare to move it. It will take over an hour to move this monster of balsa wood, fiberglass and resin. The interior may be hollow, and the walls do not exceed twenty centimeters, the whole thing weighs 35 tons. Every week, a dozen of them come out of the Siemens Gamesa factory, a Spanish company in a joint venture with the German Siemens.
It is located in Hull, in the northeast of England, on a port in the Humber estuary, close to the sea. Impossible to transport such giants other than by sea. Soon, three similar blades and a giant metal tower will be put on a boat, to be assembled in the open sea, more than 100 kilometers from the coast. Once erected, the gigantic wind turbine will be 204 meters high, the equivalent of the Montparnasse tower.
Off the English coast, more than 2,200 of these white birds have already been landed, each time a little bigger and a little more powerful. “When I started in 2007, the turbines had a power of 1.4 megawatts. Today, we are preparing 14 megawatts”, notes, almost incredulous, Andrew Elmes, in charge of the development of Siemens Gamesa for the United Kingdom. Year after year, records are broken and the largest wind farms in the world are built off the east coast of Britain. Part of the blades from the Hull plant equip, for example, Hornsea One, opened in 2019: 174 turbines 120 kilometers from the coast, 30 meters deep, with a total capacity of 1.2 gigawatts. On paper, it’s as much as a nuclear reactor.
40% of their theoretical power
On paper only. The control room of Orsted, the operator of the wind power plant, is located in Grimsby, on the opposite bank of the Humber. In a building overlooking the port, a multitude of screens monitor in real time the electricity generated on this gray day at the end of April. “Right now, we’re producing 181 megawatts, that’s not a lot”, notes the operator. Or one-seventh of the maximum production. Nothing abnormal: the wind is by definition intermittent, blowing more or less strongly. On average, offshore wind turbines operate at 40% of their theoretical power.
The entire British energy gamble lies in this difficulty. In a decade, the United Kingdom has become the second country in the world for offshore wind turbines, with 10.5 gigawatts installed, twice less than China but twice as much as Germany and four times more than the Netherlands. Bas (France will only open its first offshore wind farm at the end of the year). “It’s the great success [britannique] of the last decade »says Michael Grubb, professor of energy and climate change at University College London.
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