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telescopic tower, both made of concrete, with a 5MW

Siemens Gamesa turbine on top. The structure can be fully assembled onshore, including the turbine, and then towed to the installation site where, after ballasting the

GBS to the seabed, conventional heavy-lift strand jacks which are reused to lift one tower level after the other, lifting two sections weighing a total 960 metric tons into their ? nal positions. The recoverable jacks that lift each level are supported by the one below, which also guides the hoisted tube as it rises, in a self-installing procedure in which the tower itself is the only supporting structure required. All works are carried out from a single access platform, which is removed once the turbine is installed.

The consortium – comprising Esteyco, Siemens Game- sa, Ale Heavylift, Dewi GmbH and PLOCAN (the Oce- anic Platform of the Canary Islands) – claims this method could reduce installation costs by more than 35% when compared to jackets or XXL monopiles in deeper water (35 meters plus). The project partners also say the design is scalable and would be “a readily available means” to install new 12MW turbines.

Room for improvement

The ? rst offshore wind project was built in 1991, at

Vindby, Denmark (and is now decommissioned), and there’s now more than 18GW of offshore wind capacity. “But, to put that in perspective, the global onshore wind capacity is about 600GW,” says Barla. “So, from a vol- ume perspective, offshore still has the biggest room for improvement.” This could be in policy, process, technol- ogy and then supply chain, he says.

In terms of technology, there’s a move toward use of carbon ? ber in blades. “Historically, manufacturers have been reluctant to make investment into sourcing carbon ? ber because it’s expensive, and with very few supply- ing it, controlling the supply chain can be challenging,”

Barla says. “If you look at the biggest players, Siemens

Gamesa, all their offshore turbines have been glass ? ber.

Now, they’ve announced the 8MW DD167, a prototype of which was installed a few months ago, and the 10MW

DD193, both of which incorporate carbon ? ber. There’s been a paradigm shift in the largest players in the industry.” “In terms of processes, we are still not there yet,” he adds. “It you talk about the automotive industry, with as- sembly lines and ef? ciency, they are far ahead, but they’re a 120-year-old industry. Offshore started many years ago, but the real commercial projects only started in the last seven years. There is still a huge learning curve, Europe and globally.”

But, while there’s room for improvement, the les- sons already learned in Europe can be replicated now in newer markets – such as in the US and Asia – to help them scale up faster. 18-31 OE MayJune 2019.indd 27 6/10/2019 4:36:15 PM