Sif and Smulders complete study on Tripod foundation concept

Sif and Smulders recently completed a feasibility study on the Tripod foundation concept.

Smulders and Sif realized that the Tripod basis had been overlooked by the market in September 2020. Due to this, Sif and Smulders announced that they would conduct a cooperative research effort to determine whether and how it would be possible to revive the Tripod foundation in order to create a new Sif-Smulders product line for deeper seas and difficult soil conditions.

Abandoned concept

The Tripod foundation concept was dropped ten years ago since it was discovered to be inferior to a monopile or jacket foundation in terms of competitiveness. In compared to jackets, it was too heavy, and the Tripod’s production was more involved than that of monopiles.

The more affordable monopile foundation for shallow waterways eventually took the place of the Tripod foundation on the market, with jackets being used in deeper waters or in soil types that weren’t suited for monopiles.

The Tripod was last used in the Global Tech 1 wind farm roughly nine years ago. Its 400 MW capacity was reached by deploying 80 Tripods in water that was between 38 and 41 meters deep. The playing field for foundations has shifted in recent years as more wind farms are constructed in deeper oceans. Today, monopiles are employed in waters up to 50 to 60 meters deep, and jackets are used as a backup option.

Investigating the Tripod’s feasibility

There are two key advantages to the tripod design. First off, building a Tripod is less expensive than building a jacket foundation. Second, the Tripod has a larger potential for use in deep waters because to its more durable structure than a monopile. Smulders and Sif established a goal for the Tripod to be produced at a rate of two units per week and sought to build a Tripod with a capex-installed akin to a jacket.

The largest challenge is not designing the ideal tripod for deeper seas, but rather reducing the Tripod’s weight below the target weight specified in order to achieve a capex-installed of a comparable jacket.

After experimenting with various design solutions in order to determine the one that allowed the Tripod foundation to achieve its lowest weight while maintaining the advantages of serial manufacture, the conclusion is that, at the current price of steel, the Tripod is still about 15% more expensive than a comparable jacket. However, this disparity can be reduced by a half based on steel prices prior to the Russia-Ukraine war.

As a result, for the identical conditions, a capex premium of 5 to 15% (or around a difference of €1 million per foundation) will apply when compared with a jacket design. The installation costs of a jacket and a Tripod are comparable, despite the fact that a jacket design for the same conditions would cost an additional €1 million per foundation.

Despite the fact that Smulders created a serial production approach that drastically decreased fabrication costs, this does not entirely offset the Tripod’s weight gain and its accompanying cost. 

Niche product

As a result, the Tripod will serve as a niche product for particular projects including difficult soil conditions that make monopiles inappropriate or other external factors (such as ice loading) that forbid the use of jackets. A region that might experience these difficult climatic conditions and make the Tripod the foundation of choice is the northern part of the Baltic Sea.

Given that a weekly output of two Tripods has been demonstrated to be realistic, supply chain issues may also cause the Tripod to be chosen as the cornerstone for some projects.

The Tripod has been revived, is prepared, and is awaiting the perfect project.

Image source: Sif

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