PO071

Cost effective jacket foundation development to support the current and next generation of offshore wind turbines.

Norman Skillen 2
1ST3 Offshore sp. z o.o., Szczecin, Poland, 2Salzgitter, Berlin, Germany

Abstract

With many Developers planning offshore wind farms in increasingly deeper water, and with increasing turbine sizes, the demands and resultant forces on fixed foundations have never be greater.  Most developers have two main fixed foundation choices; monopiles, or jacket foundations.   The monopile is a mature solution, and many in the industry think that monopole is close to reaching its  limits.   However, the jacket is still a relative newcomer, and has significant design optimisation potential while offering a lighter more stable alternative, and in most of the steel price cycle,  an attractive cost alternative to the monopile. 

This presentation focuses on how jacket foundations are being developed, from a fabricator's standpoint,  to cope with increasingly water depth and larger heavier turbines.  Questions this presentation will seek to answer include:

With the downward forces on a foundation increasing with turbine size, these forces must be distributed through the foundation and for today's larger turbines and expected turbine development, jacket foundations present a technical and commercial alternative to just building larger monopiles.

Method

Using Europe's newest and most advance offshore wind foundation serial manufacturing plant, ST3 Offshore, working with industry partner Salzgitter and a number of major Developers, has pioneered the development of an industrial standard jacket foundation, that is adaptable for the majority of seabed, water depth and turbine requirements.   The industrial (standardised) jacket foundation is built using prefabricated nodes,  standard pipes and serial production techniques.  The pre-fabricated nodes are prepared using robotic welding and automated manipulation as part of the serial production process.  An overview of jacket manufacture will be presented, including the use of robotic welding, assembly and foundation outfitting,  using a real live example of an offshore windfarm currently in the construction phase.

Results

 

ST3 Offshore has now built a number of standardised jackets and found that in terms of a significant contribution to LCOE, and solving the challenges of weight reduction while being able to support ever increasing turbine weights and forces, the ST3 standardised jacket with associated serial manufacturing, offers Developers a real alternative foundation solution.  This jacket solution is a lower cost and environmentally friendly solution, particularly when considered within the lifecycle cost of the offshore wind farm.  Presentation will highlight results to justify these claims.

Conclusions

With the challenges of building out wind farms in deeper Round 3 locations, and other deep water locations, the ST3 Offshore fabrication development work has shown that jacket foundations can continue to help solve the technical and environmental challenges of deeper water and heavier turbines while still contributing to reducing LCOE.  The technical and cost impact is real as witnessed by recent foundation awards, and the significance is that the UK will continue to see more jacket foundations benefits, including environmental benefits, over the next decade.   

Objectives

This presentation will give an up to date overview of leading edge jacket foundation development and the role that jackets are currently playing in offshore wind foundations.  Delegates working in offshore wind foundations in roles that consider foundations for turbines, towers and transport and installation, will receive an insight into how jacket foundations will continue to standarise to meet future wind farm requirements, and provoke thought for other areas of the wind farm that will interact with the jacket foundation.  This presentation will also provide an appreciation of robotic welding and serial production.