Offshore Wind Turbine Foundations -OffshoreWind.net

Offshore Wind Turbine Foundations- Current & Future Prototypes

Current Foundation Types- includes foundations currently available to offshore wind developers

Future Prototypes- includes floating and deepwater concepts

Offshore Wind Foundation Overview

(Source: NREL)

Foundations Used On Utility-Scale Offshore Wind Projects Today:

The common foundations used for current offshore wind projects are shown in the diagram below

Mono pile- Consists of a steel pile which is driven approximately 32-64 ft into the seabed.

Gravity foundation- Currently used on most offshore wind projects, the gravity foundation consists of a large base constructed from either concrete or steel which rests on the seabed. The turbine is dependent on gravity to remain erect.

Tripod foundation- Designs tend to rely on technology used by the oil and gas industry. The piles on each end are typically driven 32-64 ft into the seabed, depending on soil conditions. This technology is generally used at deeper depths and has not been used on many projects to date.

For additional information on commonly used offshore foundations click here

Overview- Basic Offshore Wind Turbine Foundation Types:

Note: Drawings not to scale, demonstrates simplified design concepts for the purposes of education only. Accuracy not warranted.
(sources used in this section include the Danish Wind Industry Association)

Deep Water Foundation Concepts:

While deep water concepts have huge potential, current floating offshore wind foundation technology is not used on a commercial scale and has little operational track-record. Many of the proposed concepts utilize designs borrowed from the oil and gas industry. The advantages of deep water offshore wind is that winds are stronger further from shore and projects can be invisible from the shoreline lowering the chances of opposition. Cost may be one of the biggest challenges facing deep water offshore technology.

Several prototypes for offshore wind floating foundations exist including the ones seen below considered by MIT, NREL and DOE:

Overview-Floating Turbine Foundation Prototypes:

Depicts deep water concepts considered by MIT, NREL and DOE. Drawing based on image from NREL.
Note: Drawings not to scale, demonstrates simplified design concepts for the purposes of education only. Accuracy not warranted.

Grounded Deep Water Concepts:

Best known to North America is Winergy's Mobile Self-Installing Platform (MSIP) which is slated to be first utilized off of Plum Island, NY. As proposed, the turbine would sit on a three legged foundation. The foundations legs would each extend to the bottom of the seabed. Installation would take place on land and the turbine could be towed out to sea.

Floating Concepts:

While several floating offshore wind concepts exist, two designs are the best known:

Blue H Technologies, a Dutch company proposing an offshore project off of Massachusetts, has launched a test an 80 Kw Submerged Deepwater Platform (SDP) off the coat of Puglia, Italy. The company uses a tension-leg platform design which relies on a platform that floats below the surface of the water (similar to the ballast stabilized concept below) moored to the bottom with chains. The design is unique in that it uses a two bladed turbine. The company has proposed an offshore wind project using this technology off the coast of Massachusetts

Blue H Prototype:
Blue H Floating
Source: Blue H

The SWAY concept consists of a floating spar buoy that is some 640 ft tall, designed to rise and fall with wave activity. The concept is unique in that the turbine will face downwind. A prototype of the SWAY concept will likely be installed by 2010.

SWAY Concept:
SWAY
(Source: SWAY)

Additional Resources: (more to come)

NTVA Wind Power Offshore Presentation

Danish Wind Energy Association

SWAY floating turbine concept

Winergy

Blue H

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Last Updated: May 8, 2008
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