Jaime de Rábago · PRECAST CONCRETE WIND TOWERS AND OFFSHORE FOUNDATIONS: A HUGE MARKET COMING AHEAD

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PRECAST

CONCRETE

WIND TOWERS

AND

OFFSHORE

FOUNDATIONS:

A HUGE MARKET

COMING AHEAD

Jaime de Rábago,

Managing Director, Consolis Hormifuste S.A.

Madrid, 13/05/2011

EOI: Claves para emprender en renovables

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Content

About Consolis Group

About Consolis Hormifuste

Understanding wind

Consolis Hormifuste products and services

Consolis Hormifuste onshore

Consolis Hormifuste offshore

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Consolis history

100+ years of history

Consolis Oy in Northern Europe

Bonna Sabla in France & North Africa

Today, European leader

in pre-cast concrete industry

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Activity area (23 countries):

• Europe

• North Africa

• Asia

Personnel: ~ 10000

Turnover: + 1500 M€

Factories: ~ 130

Headquarter: Brussels

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Solutions for

•Residential & non-residential

buildings

•Railways

•Civil works (pipes,

environment etc.)

•Unlimited…

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Continuous innovation

Consolis Technology (Finland-France) at

the cutting edge

Developing pre-cast concrete concepts,

products, manufacturing processes and raw

materials to improve productivity and quality

Technology Roadmap

boosting internal co-operation

Consolis Innovation Training (CIT)

• intensify & better manage innovation

• improve the transfer of best practices

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People & practices

Skills development – a top priority

Training – a major investment

Consolis Academy

Transfer of best practices (TOB)

sharing experience among Consolis companies

International functional networks

sharing knowledge and building synergies

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Respect for the environment

New ideas for sustainability over the entire product life cycle

better use of materials

production with reduced environmental burden

design for re-use/dismantling/recycling

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The wind tower centre of Consolis, located in Madrid

Since 2008 a member of Consolis Group and since 2005 in the renewable energy business.

Coordination of product development and design

Certification of solutions

Customer relationships

Coordination of marketing and sales

Consolis Hormifuste S.A.

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Understanding wind

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How we obtain the energy from wind?

FORMULA: and

So, energy is:

in square proportion to rotor diameter

in cubic proportion to wind speed

Wind energy basics

A: Area of the rotor

D: Rotor diameter

V: Wind speed

P: Power output

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hub height

rotor diameter

... both parameters of

paramount

IMPORTANCE

to increase

energy production

Wind energy basics

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110

100

90

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60

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The world wind industry

Today: nearly 200.000 Mw

installed in a global scale

-Year 2015: 500.000 Mw

-Year 2020: ….nearly

1.100.000 Mw!!

-Wind industry: growth,

growth, growth

One tower (windmill) = 2 - 5 MW

On-shore / off-shore0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

1,000,000

1,100,000

1990 2010 2015 2020

MW

Cumulative Global Wind Power Development

Prediction Forecast Existing capacitySource: BTM Consult - A Part of Navigant Consulting -March 2011

Actual 1990-2010 Forecast 2011-2015 Prediction 2016-2020

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The evolution of MW

per WTG in different

segments is as follows

(average composed

nominal power)

2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

100%

90%

80%

70%

60%

50%

40%

30%

20%

10%

> 2,5 MW 1,5-2,5 MW 0,75-1,49 MW < 0,75 MW

Source: real data up to 2009, then, own estimations

From MW to concrete towers

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A market of bigger and higher machines…

1970 1980 1983 1985 1987 1990 1995 1998 2000 2003

10 15 20 25 30 50 60 70 85 110

5 11 12,5 20 23 48 58 61 77 116

5 20 30 100 100 600 1100 1200 1500 5000

Year

Height (m)

Rotor Ø (m)

Power (kW)

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Why concrete towers for the wind industry?

… there are technical reasons…

Less maintenance requirements

More flexibility of construction and design

Better dynamic response (less vibrations and fatigue)

Better transportation possibilities

Precast plants can be easily adapted for manufacturing of

concrete towers

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… and economic reasons

Variation of steel prices

With greater and higher wind

turbines (> 100 meters), the

concrete solutions for towers is

cheaper

The tower can account for up to

20-25% of the total wind farm cost

and this percentage increases

with greater turbines

Why concrete towers for the wind industry?

60 70 80 90 100 110 120 130 140 150

Approx. cost comparison

between concrete and steel

wind towers

Concrete

Steel

Tower height (metres)

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Consolis product range for wind farms

Onshore

• Hybrid precast concrete-steel towers

• Full precast concrete tower

Offshore

• Precast concrete gravity based foundations

Consolis does

Design

Production

Transportation to the building site

Assembly and other site works

Post tensioning

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Hybrid precast

concrete-steel tower

- max height 150 m

Post tensioning

cables

Steel part

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Full concrete tower

- max height 105 m

Intermediate slab

Post tensioning

cables

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Consolis

Hormifuste

solution

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1. Technical Introduction

1.1 Basic Vocabulary

1.2 Classical Structures vs. Wind Towers

2. General Calculation Scheme

3. Calculation Process

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3

4

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Wind Turbine Manufacturer Data

Geometry and Post-tension

Pieces reinforcement

Joints

Consolis Hormifuste solution

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1. Technical introduction

1.1. Basic Vocabulary

• Geometry: tower shape

• Joints: connections between pieces

•Own frequency of structure: dynamic behaviour parameter to be

controlled in order to avoid interaction with the turbine→ Resonance

• ULS: Ultimate Limit State of strength, stability and fatigue. Loads that

should cause the collapse of the structure

• SLS: Serviceavility Limit State. We differentiate between extreme loads

(50 years return period) and frequent loads (one year return period)

• Fatigue: Time repeated loads → load cycles and damage accumulation

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1. Technical introduction

1.2 Classical Structures vs. Wind Towers

In an classical structure ,design is

conditioned by SLS and ULS. Once we

have the structural design the fatigue is

checked.

In concrete wind towers initial design is

conditioned by SLS and fatigue. After this,

ULS are checked. Fatigue is determinant in

calculation, as the cycles are huge (108)

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2. General Calculation Scheme

WT Manufacturer Data

Max. Fatigue Load

Geometry and

Post tension

Own

Frequency

SLS

Pieces

reinforcement

Geometry

Modification

General

Joints

Vertical

Horizontal

Fatigue

Loads

Accumulated damage

ULS, shear and torsion

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3

4

2

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3. Calculation process

Wind Turbine Manufacturer Data

Main data to be provided by Wind Turbine Manufacturer:

Loads and Markov Matrix of bending moments at different heights of the

tower

Clearance: Minimum distance to maintain between blade tip and the

tower.

Frequency: Tower Frequency used in loads calculation.

1

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Ring Number

of

elements

per ring

Weight of

each

element

1 6 25,4

2 6 26,9

3 6 26,4

4 5 28,2

5 5 24,7

6 4 24,5

7 4 22,8

8 3 28,3

9 3 26,1

Detailed geometry

Once the geometry and

post tension is

confirmed, the tower is

divided in precast units

(rings and elements per

ring)

Geometry and Post-tension2

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Reinforcement of precast elements


Horizontal reinforcement is

necessary to support shear and

torsion forces caused by temperature

gradient between inner and outer

part of the tower

Vertical reinforcement is only

necessary for handling of pieces

Pieces reinforcement3

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Joints4


Detail of the horizontal jointDetail of the vertical joint

Proper

reinforcement

and grouting of

vertical joints

during assembly

will assure the

monolithic

behaviour of rings

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Our first project:

100 metres hybrid towers in Finland

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Consolis Hormifuste solutions for offshore

Since 2007, Consolis-Hormifuste has carried out several works concerning offshore

wind turbines. These works range from basic studies to the designs of a concrete

foundation structure, designed to perform in different conditions.

The following studies have been developed until now:

•Research proposal for offshore concrete foundations for wind turbines

• Structural and stability calculations for an offshore windturbine foundation

• Foundations for offshore wind turbines: state of the art

• Founfations for offshore wind turbines: Analysis of structural solutions

• Foundations for offshore wind turbines: Analysis of a conical caisson in locations with

25 m of depth

• Foundations for offshore wind turbines: Analysis of precast pieces for a foundation

structure in locations with 25 m of depth

In the following slides, a summary of these works is made.

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RESEARCH PROPOSALS

In this study, a brief and preliminar state of the art was made, and some researchlines were proposed:

• Predesign abacus

• Construction methodologies

• Economic evaluations

• Environment evaluations

Some of these lines would be developed then in the following works

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STRUCTURAL AND STABILITY CALCULATIONS FOR

AN OFFSHORE WIND TURBINE FOUNDATION

Here, a design of a foundation made of a reinforced concrete caisson was developped.

The caisson was designed for depths from 10 to 30 meters, and with the ability to betransported afloat .

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ANALYSIS OF STRUCTURAL SOLUTIONS

Two structural solutions were studied here, both of them valids to perform at depths of

50 m.

Both solutions were designed to be transported afloat.

Solution #1: a

conical caisson

supporting a

cylindrical structure

Solution #2: three

piles supporting a

cylindrical structure

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CONICAL CAISSON IN LOCATIONS FOR UP TO 25m SEA DEPTH

(2009-2010)

It was inferred from the former study that the conical solution had lower costs than thethree pile solution.

A foundation structure for 25 m depth, made of a conical caisson which was able tobe transported afloat was designed.

The following calculations were carried

out for this solution:

•Buoyancy of the foundation structure

•Geotechnical stability

• Structural calculations

• Estimated costs

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ANALYSIS OF PRECAST PIECES FOR A FOUNDATION STRUCTURE

IN LOCATIONS FOR UP TO 25m SEA DEPTH

Finally, a design of the conical caisson making

use of precast pieces was developed.

-The foundation structure was made to perform

up to 25 m depth.

-It was designed to be built on the coastline

and then transported afloat.

-The reinforcement was made with

post-tensioning tendons, due to the high tensions.

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Offshore foundation for

up to 25m sea depth

Bottom diameter: 22 m

Height of conical part 18,5 m

Total height 25 m

The foundation has vertical

and horizontal post tension.

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Offshore costs... the big battle in the

coming years

Cost comparison? Not yet possible in real terms:

A lot of different sites, depths and tipologies

Good reference: Vattenfall Kriegers Flak conceptual

foundation study (5Mw, 35 metres, 40 foundations, 5 types:

between 2,4 Meur to 3,8Meur)

Our solution has a clear aim: reducing cost in the production

phase. Transportation and installation should not vary a lot

from other solutions.

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Precast advantages for offshore...

Serial production as big amount of pieces to be

precasted

High quality guaranteed at factory

Pieces easy to transport (no more than 20 tons each)

to harbour or to coastline

Small area needed in harbour and or coastline

Possibility of keep independent production from

installation: not dependent on weather conditions…

Sea tranportation not too difficult…

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We want to avoid this...!

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.. and even this...!

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CONSOLIS HORMIFUSTE S.A.

C/ José Silva, 3 4ºD

28043 Madrid (SPAIN)

[email protected]

www.consolis.com

Let’s harness wind together!!

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Jaime de Rábago · PRECAST CONCRETE WIND TOWERS AND OFFSHORE FOUNDATIONS: A HUGE MARKET COMING AHEAD