Page 69: of Offshore Engineer Magazine (Sep/Oct 2013)

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“The stability of the foundation is

EPIC ensured by a combination of earth pressures on the skirt and the vertical capacity of the foundation,” he says.

There have been questions about the bucket foundation: Installation in seabed that is too rocky presents challenges; manufacture requires a lot of welding; delivery and installation methods remain to be perfected.

Universal has answers for all of the questions: If installers encounter unexpected rocks, the bucket founda- tion is easy to shift slightly; the relative shallowness of its penetration into the seabed, compared with traditional suc- tion piles, also helps when installing in potentially problematic seabed.

As for the welding in manufacturing, promoters say it is a beneft because it enables the cost savings associated with unitization.

As for hauling and installation, exist- ing jackup vessels have the capability needed for delivery, and other hauling options are being studied for larger projects; installation has been proven at Dogger Bank and will be optimized in future projects, Universal says.

But the bucket foundation has to do more than work effectively to be com- petitive. It has to cost less.

The Carbon Trust’s head of offshore wind, Phil de Villiers, warned a recent

UK conference that offshore wind power development could stall without more powerful turbines, lower-cost founda- tions and full-scale demonstrations that the technology can be cost effective.

Cost is clearly an issue; especially with offshore turbines costing as much as four times onshore turbines, in the range of £3-4 million per MW of capacity.

Universal is happy to talk about cost.

They estimate the design can shave 30% off the cost of traditional subsea foundations (the old-style monopoles, jackets and gravity bases).

First, the bucket foundation is much lighter. It uses less steel. “Compared to monopiles, we expect to demonstrate a 25-30% reduction in weight,” says

Universal spokeswoman Michelle

Fred. Olsen Windcarrier’s

Maria Langkilde.

jackup Brave Tern was used

With the transition piece already to install Universal’s bucket attached, installation requires fewer foundation. Engineers are steps. Importantly, the design avoids studying additional installation the grouted connection that can lead to options.

Photo: Maersk future problems.

oedigital.com September 2013 | OE 71 070_OE0913_EPIC4 forewind.indd 71 8/18/13 8:34 PM