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Wednesday, 12 March 2014
11:15 - 12:45 On- and off-shore installation technologies
Hardware Technology  

Room: Tramuntana
Session description

Installation of wind turbines is an area that has attracted significant attention, in an attempt to increase efficiency and reduce costs. Bigger, better, cheaper ways of transporting and installing turbines are vital in the drive to reach grid parity. Onshore, increasing tower heights lead to alternative materials and assembly procedures. Offshore, costs can be reduced by optimising design, transportation and installation of foundations.

Learning objectives

  • Discover the design concepts and assembly procedures that ensure steady installation rates of concrete towers
  • Identify the current challenges and solutions in the installation of new onshore technologies
  • Summarise the calculation, design and manufacturing criteria for optimised offshore monopile foundations
  • Examine the savings in materials and cranes derived from an innovative transportation and installation structure for a floating foundation
Lead Session Chair:
Jose Luis Sevillano Izarra, GES, Spain

Thorsten Kramer, GES
Iván Garcia Maestre Acciona Windpower, Spain
Iván Garcia Maestre (1) F P
(1) Acciona Windpower, Noain, Spain

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2014 and are published here unedited

Mr. Garcia Maestre has been working in different companies in the structural engineering field for almost 10 years. During these years his main responsibilities have been related with structural analysis (FEM, concrete, steel, pathologist, design). He studied industrial engineering at the UPM (Spain) developing his master thesis at NTNU (Norway). He started to work in renewable industry since 2006 and has been involved in several projects linked with towers and foundations for windturbines. Nowadays he is the head of support structures group in R+D+I Acciona Windpower Department and he has several patents related with foundations and concrete and steel towers.


Industrial Assembly of 120m HH Concrete Tower


The present work focuses on the concepts, developments, technical analyses, procedures and assembly processes that AW has developed so that the concrete tower of 120m HH reaches an assembly rate of 2 towers per week, every week, in any emplacement.
From the initial tower concept up to the assembly procedures, everything has been conceived so that the assembly is an industrial assembly: a global product, with the same processes, easily repeatable in the same periods, with certified quality (GL), in different countries, with different weather conditions and with local human and materials resources.


The market demands higher towers, bigger rotors, greater production and lower costs, which means, a more efficient COE (cost of energy). The local production of concrete towers is the way of obtaining this, but it must go accompanied of a fast, robust, repeatable and reliable assembly with high rates of towers assembly.
Grouting procedures, tower and nacelle erection processes without intermediate steps, joint sealing systems, solutions for assembly under cold climate conditions, use of local materials, etc. are solutions that allow us to minimize the cost of assembly and reach high assembly rates.

Main body of abstract

While it is true that the concrete tower technology has clear advantages, one of the main drawbacks is that the assembly needs more activities, which implies lower assembly rates than the ones obtained with a steel tower.
AW does not only have a tower concept that allows reaching assembly rates of 2 towers per week, AW also installs 2 towers per week, in wind farms of 20, 40 or 80 turbines. What do we do to obtain it?
- We have a tower concept : big and extended pieces, with variable number of keystones per section, which reduces the lifting operations and the number of joints (INN1-US US8505244B2)

- That allows us to plan the parallel assembly in several towers simultaneously: the keystones pre-assembly phase and the sections assembly phase are well differentiated (INN2-US US7765766B2 and INN2-US2 US8381487)

- And we have particular solutions which optimize every phase of assembly:
o Sealing of vertical joints: up to 3 developed and tested methods to choose depending on the weather conditions
o Erection the tower sections and nacelle more without horizontal joints (US2013001954A1.pdf).
o Grouting of vertical and horizontal joints, with pumping of up to 100m heights, from -20 up to 40ºC. (ES201230287)
o System for assembly in low temperature conditions. (ES201331008)
o Installation of post tensioning cables in 1.5 days
o Reduction of grout curing time and elimination of waiting times. Adjustment of minimum necessary resistance in every phase of assembly


The technology of precast concrete towers of AW is a mature technology with over 200 towers installed that allows and ensures high assembly rates of 2 towers/week, with clear advantages in terms of local content and production and COE optimization.
This technology solves the industrial assembly of concrete towers over 100m hub high, with well-defined and controlled processes but flexible enough to be adaptable to new environments or planning changes.

Learning objectives
Only the development, the detailed analysis, the optimization and the application of industrial criteria to every assembly phase makes the concrete tower concept with industrial assembly a reality