MB Concrete Solutions Wind Towers Nov10

Offshore and onshore wind farm development

Concrete Solutions for Wind Tower Foundations

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ContentsIntroduction 3With wind tower projects in the UK rapidly increasing the

challenge for the UK wind industry is to facilitate development

of alternative solutions to ease pressure on the supply chain and

drive down costs. Concrete can assist with this challenge.

Thebenefitsofconcrete 4Concrete is an ideal material in the construction of tall, strong,

sophisticated wind farm structures, for onshore or offshore

deployment, in aggressive marine or remote inland environments

requiring durable materials and details as a matter of course.

Onshoresolutions 6Concrete gravity bases provide an ideal solution when

constructing the foundations of onshore wind farms.

NewUKoffshorewindzones 6A variety of concrete gravity base solutions currently under

development are well placed to meet the needs of the

approximately 7,700 wind energy pylons commissioned through

Round 3 development zones and Scottish Territorial Waters

development licences.

ConcretefoundationsolutionsGBF ® (Gifford/BMT/Freyssinet) 7Arup/Costain/Hochtief 8DTI 50 design concept 9Consolis Hormifuste 9Vertax 10 Xanthus Energy 10

Constructionrequirements 11To minimise costs, the construction process for gravity bases

must be simplified and achieve high repeatability; a challenge

well within the scope and potential of concrete construction.

Summary 11Concrete offers a variety of durable, sustainable and economic

solutions for wind towers and foundations, and is easily adaptable

to meet specific wind farm requirements.

ForewordThere is no prescriptive plan for the development of a wind farm,

whether onshore or offshore. Each prospective site is unique, with its

own mix of physical, economic and access constraints. This document

demonstrates the key role concrete can play in realising cost-efficient,

sustainable and constructible energy converters; addressing the major

issues relevant to any onshore or offshore wind farm development.

Concrete is uniquely adaptable in terms of performance, design

and constructability, making it the material of choice for wind tower

foundations and a viable option for the towers themselves.

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Concrete Solutions forWind Tower Foundations

IntroductionTheprovisionofwindenergyfrombothonshoreandoffshoresourcesisfundamentalinenablingtheUKtomeetitscommitmentofproviding15percentofenergyfromrenewablesourcesby2020.Thistargetisaseven-foldincreaseinrenewableenergyfromthe2008level.

In order to play its part in meeting this renewable energy target, set

under the EU Renewable Energy Directive, the UK wind industry is

growing at an unprecedented rate.

The recent announcement of Round 3 development zones has

confi rmed the UK’s commitment to the target, and will provide the

construction industry with over £100 billion of new work. For this

offshore development, many of the prime sites in shallow water have

already been used so deeper sites further from the shore will become

more common. The next 10 years will witness the delivery of the largest

ever programme of wind farm development in the UK. This rapid growth

in the market will require the development of alternative foundation

solutions which by necessity have to be both economic and deliverable

in a challenging environment.

The challenge for the UK wind industry is to facilitate development

of new solutions to ease pressure on the supply chain, while also

developing different methods of working to drive down costs. Turbine

technology has advanced rapidly to offer turbines with a capacity up

to 5 MW, while 10 MW units are under development. To accommodate

these ever larger turbines, the towers need to be taller and more robust

than previously required.

Concrete gravity bases meet all the requirements, and are increasingly

considered by developers and contractors as an economic solution for

wind farm developments.

This brochure sets out the benefi ts of utilising concrete gravity bases

for wind farm construction, and also provides an overview of several

proposed solutions.

This brochure serves as an accompanying document to

Concrete Towers for Onshore and Offshore Wind Farms,

published in partnership with Gifford in 2007. The original

document presented ideas and issues related to the

deployment of concrete towers

and associated structures, and

highlighted a real opportunity

for the future of concrete in

the wind energy market; then

a conceptual view but now

coming to fruition. Work has

advanced since the 2007

publication, with a number

of examples following in this

document. Please refer to the

References section (page 11)

for more information.

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Round3Sites1.MORAYFIRTHMoray Offshore Renewables (EDP Renovaveis, SeaEnergy Renewables)

2.FIRTHOFFORTHSeaGreen Wind Energy (SSE Renewables, Fluor)

3.DOGGERBANKForewind Ltd (SSE Renewables, RWE Npower Renewables, Statoil, Statkraft)

4.HORNSEASMart Wind Limited (Mainstream Renewable Power, Siemens Project Ventures)

5.NORFOLKBANKEast Anglia Offshore Wind (Scottish Power Renewables, Vattenfall Vindkraft)

6.SOUTHERNARRAY(FORMERLYHASTINGS)Eon Climate and Renewables, UK Southern Array Ltd (Eon Climate, Renewables UK Developments)

7.WESTISLEOFWIGHTEneco Round 3 Development Ltd (Eneco New Energy)

8.BRISTOLCHANNELBristol Channel Zone Ltd(RWE Npower Renewables)

9.IRISHSEACentrica Energy RenewableInvestments Ltd (Centrica)

For wind farm sites in

Scottish Territorial Waters,

see page 6.

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ThebenefitsofconcreteforwindenergyfoundationsandpylonsThewindindustry ’sidentifiedneedforincreasedturbinesizes,rotordiametersandtowerheightsmakesconcreteacompetitiveoption.Concrete’sversatilityenablesdesignsolutionsunlimitedbyheightorsizetomeetchallengesfromsiteconditionsandaccessibilityconstraints.Itwillpermitfavouredconstructionmethodstobeusedtogetherwithspecialistproductiontechniques.

LowmaintenanceConcrete is an inherently durable material, capable of maintaining its

desired engineering properties under conditions of extreme exposure.

Concrete’s constituent materials can be easily tailored to economically

provide different degrees of durability depending on exposure,

environment and further desired properties. Overall durability can

be ensured by placing more sensitive structural elements such as

prestressing strands in protective sheaths or, if external to the concrete,

inside the pylon. With design lives for offshore wind farms in particular

on the increase, concrete’s inherent durability leads to reliability;

resulting in wind towers with minimal maintenance requirements

throughout their service life.

DesignandconstructionflexibilityWind farm developers require maximum power output from their

sites, which can be achieved using higher-output turbines operating at

heights in excess of 100m. Concrete’s versatility enables design solutions,

unlimited by height or size, to meet challenges from site conditions

and accessibility to favoured construction methods and availability of

specialised production.

Efficiency can be realised by optimising either in-situ or precast concrete

construction methods. High quality sections can be precast in factories

under controlled conditions and transported to site in units limited only

by size and weight. Simple jointing details are easily achievable with

precast concrete units, leading to cost-effective formwork solutions

and fast and efficient construction. In-situ concreting takes advantage

of proven construction techniques and formwork solutions to deliver

quality and efficiency. Any initial investment in formwork will be offset

through its multiple uses over long production runs, giving lower unit

costs. Concrete can be supplied by established ready-mix suppliers who

have a track record of controlled supply from well-understood materials

or alternatively from on-site mixing. With a state-of-the-art mobile onsite

mixing plant, in-situ construction can easily overcome transportation

issues associated with more remote sites.

MaterialflexibilityConcrete is an adaptable construction material, which can be finely

tuned through alterations in mix design to optimise parameters such

as strength, stiffness, density and heat generation during curing. Recent

concrete technological advancements, including the use of chemical

admixtures and alternative reinforcement options, allow the production

of very high strength, stiff, light-weight and corrosion-resistant solutions.

A study [1] into carbon fibre reinforced polymers (CFRP) showed that

in view of enhanced material properties and reduced concrete cover

requirements, the weight of a concrete wind tower prestressed with

CFRP would be about 40 per cent lower than that of an equivalent steel

prestressed structure.

As such, the range of diameters and thickness of sections available to

concrete wind tower designers is much greater than when working

with other materials; allowing a wider range of solutions and adaptable

construction methods.

AvailabilityofconcreteconstituentsConcrete is the most widely used construction material. It is a local

material and readily available throughout the UK. Existing production

facilities will either already be established near the yard where the

gravity bases are to be pre-constructed or could be positioned adjacent

to the works with the minimum of lead time.

This approach will minimise the need for transportation of materials to

the construction site, with the associated reduction in environmental,

economic and social impact. Localised production will provide jobs for

the community and support the local economy.

D ynamicperformanceAs concrete has inherently higher damping properties than other

materials, solutions with less noise and vibration are deliverable [2]. This

is beneficial in terms of not only structural demands such as fatigue

failure but also public acceptance issues in relation to noise emissions.

Use of concrete for pylons, foundations or both can generate

considerable advantages, offering design solutions potentially more

tolerant of occasional resonance and with a reduced risk of dynamic

problems. For tall offshore wind towers, for example, the use of concrete

gravity foundations instead of monopiles can offer improvements

in dynamic response. For wind tower pylons, prestressed concrete

offers high fatigue resistance, providing more tolerance and less risk

from dynamic failure. As concrete can accommodate dimensional

changes relatively easily, designs can be adapted to larger diameters

to economically produce stronger, stiffer towers and avoid transport

problems.

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WholelifeperformanceConcrete can offer cost-effective wind tower solutions. Conceptual designs

and cost studies undertaken by independent consulting engineers

[3] indicate that by taking full advantage of concrete technology and

adaptable design and construction opportunities, significant cost savings

can be achieved for wind farm developments. For tall towers in particular,

concrete can deliver large diameter, low-maintenance pylons with lower

relative grid-connection costs with the capability of generating increased

levels of power. With relatively short lead-in times for concreting works,

construction programme savings can be achieved.

SustainablecredentialsThe fundamental objective of operating wind turbines is to reduce

CO2 emissions and contribute generally to a more sustainable future.

Concrete’s environmental credentials are excellent, with optimisation

possible through conservation of materials, the use of waste, cement

additions, admixtures and recycled aggregates – all with no detrimental

impact on structural performance [4]. Responsibly-sourced concrete

improves the economic, environmental and ethical standards

throughout the supply chain. Clients are now seeking a level of trust in

products which goes beyond safety and quality. Concrete which can be

manufactured locally using readily-available materials and resources

also reduces transportation costs, a key environmental consideration

with significant social and economic impacts.

Estimates proposed by independent consulting engineers [5] have

shown that - compared to tubular steel - for a typical 70m onshore wind

tower configuration, concrete pylon designs can deliver significant

improvements in embodied energy and embodied CO2.

Due to the excellent sustainability credentials of concrete and the efficiency

of the designs the operational time required to offset the amount of energy

used to construct the gravity bases is approximately six months.

In terms of life-cycle design, precast concrete solutions in particular lend

themselves to simple deconstruction steps and techniques. For offshore

concrete gravity foundations, the employment of established flotation

techniques avoid potentially complex decommissioning processes and

environmental issues associated with driven monopiles in the sea bed.

Reinforced concrete is additionally 100 per cent recyclable, with options

including reuse of individual concrete structural units or material

crushing to provide what is now an industry-accepted aggregate source.

UpgradeableBy providing strong, stiff, durable wind tower structures with a

prolonged service life, prestressed concrete design solutions offer

the option to retrofit turbines after their design life of about 20 years

expires. Prestressing forces can be easily adapted to cope with increased

loading. Around three to four next-generation turbine life cycles could

easily be accommodated in this way; thereby avoiding the financial and

environmental costs of reconstruction. To fully realise this potential,

the structures would need to match this durability requirement; easily

achieved using concrete gravity base foundations and towers.

MarineenvironmentConcrete is a highly versatile construction material well suited to the

harsh conditions existing in marine environments. Its use in marine

engineering has been well proven over many years in a wide variety

of coastal protection projects, with concrete used extensively as the

material of choice. Concrete foundations for offshore wind energy

pylons do not need piling and will provide an economic, durable and

sustainable solution which will readily accommodate turbine upgrades

when required.

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OnshoresolutionsConcretegravitybasesarethemostcommonlyusedsolutionforthefoundationsofonshorewindfarms,withaprovenhigh-performancetrackrecord.

NewUKoffshorewindzonesIn 2010 the winners of tenders for Round 3 development zones (see page 3) were announced, this followed the award of development licences in Scottish Territorial Waters (see Table 1). The successful bidders for these developments are now taking the development process forward, prior to the commencement of construction.

The total renewable energy capacity to be provided is in excess of 38GW, and the resulting construction programme will require the installation of approximately 7,700 wind energy pylons in water depths of up to 60m.

The graph below, published by The Crown Estate, shows the foundation depths associated with these development zones. The concrete gravity base solutions highlighted in this document could provide solutions for these development zones.

The full range of benefits attributable to concrete enables the delivery

of durable and robust solutions, able to withstand the most challenging

of environments. The material is always readily available local to the

construction site, minimising the environmental impact of transport.

Concrete construction (both precast or slipformed) can be used for

the towers of onshore wind farms. The resultant structure is extremely

durable with high damping properties, reducing the impact of noise and

minimising vibration.

Number of installations required vs. mean water depth

Water depth range (from mean sea level)

less than20m

20-25m 25-30m 30-35m 35-40m 40-45m 45-50m 50-55m 55-60m

2000

1800

1600

1400

1200

1000

900

800

400

200

0

Num

ber o

f Ins

talla

tion

s

Bars show theminimum andmaximum numbersof installationsrequired within eachwater depth range

The low �gureassumes all 6MWturbines, the high�gure assumes all3.6MW turbines

Foundations

Table 1: Wind farms in Scottish Territoral Waters

MW capacity Developer

Argyll Array 1500 Scottish Power Renewables

Bell Rock 700 Airtricity & Flour

Beatrice 920 Airtricity & SeaEnergy

Forth Array 415 Fred Olsen Renewables

Inch Cape 905 Npower & SeaEnergy

Islay 680 Airtricity

Kintyre 378 Airtricity

Neart ne Gaoithe 360 Mainstream

Solway Firth 300 E ON

Wigtown Bay 280 DONG Energy

In-situ slipformed concrete tower. Image courtesy of Bierrum

Graph courtesy of The Crown Estate

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ConcretefoundationsolutionsFoundationsforEuropeanoffshorewindfarmshavetodatebeenmostlysteelmonopiles,whilstconcretegravitybasefoundationshavebeenwidelyusedintheBaltic.

As the new wind farm developments move into more challenging

sites in deeper waters, the existing solutions are reaching the limit of

their performance. New solutions are needed to meet the challenging

requirements of the recently announced offshore wind farms.

These solutions need to be straightforward to install, as well as

economic and sustainable. Where possible, existing supply chains should

be utilised; this will enable the sector to deliver the numbers of turbine

foundations required for the UK government to meet its commitment

towards the generation of renewable energy.

The following pages provide a summary of some of the gravity

base foundation solutions that have been proposed to meet the

requirements of the Government’s wind farm programme.

GBF®proposedfoundationsolution

The integrated solution proposed by Gifford, BMT Nigel Gee and

Freyssinet (GBF®) avoids many of the supply chain hot spots and

inefficiencies of traditional construction methods. Offshore operations

are minimized and onshore assembly works maximised; improving

safety and quality whilst enhancing productivity and surety of delivery,

as less of the process is weather-dependent.

The solution is suited to a variety of sea bed types; sand, clay and rock,

water depths between 15m and 60m and is fully removable upon

decommissioning.

The GBF® integrated solution combines three distinct advantages:

� Mass production of concrete gravity base foundations.

� Onshore installation of steel mast segments, nacelle, rotor and blades

onto the gravity base.

� Transportation and positioning of the completed turbine onto the

sea bed using a purpose built transport and installation barge (TIB).

The foundations will be produced on an industrial scale using a

production line technique. A purpose-designed un-manned transport

and installation barge (TIB) will be used to transport and install the

foundation. The TIB will be towed to the wind farm site, where it will be

ballasted to lower the foundation into position on the prepared seabed.

Once positioning has been verified, the TIB releases the gravity base,

moves away and is re-floated, ready for its return journey back to the

quayside. The scour protection can then be placed, the electric cable

connected and commissioning of the wind turbine can start. The same

TIB would be used for eventual decommissioning of the wind turbine.

The GBF® system is offered by the three consortium companies

of Gifford, BMT Nigel Gee and Freyssinet. This grouping combines

the strengths and expertise of Gifford (world renowned consulting

engineers) BMT Nigel Gee (International Naval Architects) and Freyssinet

(world leading specialist contractor.)

The GBF® solution has been selected by The Carbon Trust for

development within the CT Offshore Wind Accelerator programme.

The methods and concepts are protected by international patent

applications.

Constructionprocess

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Arup,Costain,Hochtiefproposedfoundationsolution

This solution is a self-installing turbine foundation, which can be

mass-produced in a construction facility located at ports to suit rapid

deployment to UK wind farms.

The key features of this solution are:

� Reinforced concrete non-piled ballasted gravity structure.

� Caters for water depths up to 60m.

� Suits larger turbines (up to 8MW units can be accommodated).

� Minimises the need for sea-bed preparation by accommodating

existing seabed slopes and surface sediments.

� Incorporates skirt variants to suit seabed soil conditions.

� Standard designs to enable cost optimisation.

Construction/installationprocess

� Foundations are self-buoyant for ease of deployment to the wind

farm location.

� Standard tugs (readily available) are required for towing to site.

� Reduced weather dependency.

The gravity base foundation has been developed through a partnership

between Hochtief, Costain and Arup, founded on long-term relationships

from previous projects, and combines unique capabilities to serve the

growing energy sector.

Hochtief’s strong marine competence, Costain’s civil engineering

and marine construction experience and Arup’s offshore marine and

concrete structure design expertise are the ideal basis to offer a unique

and differentiated solution, fully integrating the design, construction,

offshore installation and decommissioning of foundations for offshore

wind farms.

DEMEbuiltsolution-ThorntonBankFarShoreWindFarm,Belgium

The first phase of the Thornton Bank wind farm, which is now

complete, comprised six concrete gravity base foundations in an

average water depth of 16m - each supporting a 5MW turbine.


The foundations were pre-constructed at a facility on the

quayside and then transported to the installation site by barge,

prior to being lowered onto a pre-prepared foundation.

After final positioning, the foundation units were ballasted with

sand/gravel and the turbine system installed in a single lift onto

the foundation.

Courtesy of Arup.

Courtesy of Dredging International.

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Concrete Solutions forWind Tower Foundations

DTI50designconcept

Designconcept

The concept is a concrete gravity based structure for wind turbine

foundations. The structural support foundations, turbine tower, nacelle

and blades are delivered and installed as one unit by a purpose built

installation pontoon. The turbine tower is stowed within the main

support column, reducing the overall height by approximately 60

metres, during transit. On site, a fl otation cylinder built into the base

of the turbine tower raises the nacelle and blades to a working height

when the main support column is fi lled with water. The turbine tower is

then bolted and grouted to the working platform. By de-watering the

main support column, the turbine tower can be lowered, allowing access

to the nacelle and blades for maintenance or major repairs.

The design is engineered to allow component parts to be manufactured

by fabrication yards nationwide before delivery to dedicated assembly

yards with good quayside facilities. By spreading the workload

nationally, the social and economic problems of large workforces

working away from home can be avoided.

Advantages of the system:

� Can support 10 MW turbine in up to 50m water depth.

� Complete wind tower pre-assembled to eliminate heavy lifting on

site and minimise weather dependency.

� Self-installing foundation minimises seabed preparation.

� Modular construction enables spread of workload.

� Foundation built afl oat, requiring less land for construction.

ConsolisHormifusteproposedfoundationsolutionThis solution is formed of precast reinforced concrete components,

factory-cast for accuracy and economy with rapid assembly at a port

facility to minimise the construction period. The approach represents an

innovative design simplifying construction, without the need for large

pontoons or cranes at sea. Only standard tug boats are required for the

installation process.


The components are cast in a factory and then transported to a coastal

construction facility where they are assembled using post-tensioned

steel tendons. The completed unit is then transported by barge to

its fi nal location where it is placed over a stone bedding layer on the

seabed in water depths of up to 25m.

After lowering onto the seabed, the caisson is fi lled with ballast and the

remainder of the tower together with the turbine and rotor blades is

placed on it.

The proposed base structure is 25m in height with a diameter of 6m at

the top and 20m at its base. Computer graphic by Architech Animation Studios (UK) Ltd, Inverness.

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VertaxproposedwindtowersolutionVertax Wind leads a group of major organisations in the UK developing

the potential of its patented design of a multi-megawatt vertical axis

wind turbine generator.

The overall structure from sea bed to the electrical hub is marine

concrete with a design life of 50 years. Different seabed interfaces have

been developed to accommodate varying geological conditions. These

interfaces include a concrete gravity base or a concrete monopile. The

solution is applicable to water depths of up to 35m with a concrete

gravity foundation. For deeper waters other foundation concepts

utilising concrete foundations are under development.


The entire structure (less the seabed interface) is deployed as one

completely assembled unit, inclusive of generators and rotor. In order to

eliminate any unwanted wind loading on the blades during installation,

the blades are collapsed in their nesting position close to the tower. •

XanthusEnergyfoundationsystemSea Breeze is a self-installing buoyant concrete foundation system

proposed by Xanthus Energy. The foundation is suitable for offshore

wind farms in water depths of up to 60m.

Key benefits of the system are:

� Self-buoyant system that enables a completely assembled wind

turbine generator to be towed to the offshore site and installed

without specialist towing or lifting equipment.

� Can be manufactured close to the shoreline using local labour and

materials under factory controlled conditions.

� Minimal weather dependency for both manufacture and installation.

� Patented leveling footpads and built-in scour protection suits

virtually all sea bed conditions.

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ConstructionrequirementsEachofthesolutionsreferredtowillrequireafullassessmentoftheirspecificconstructionrequirementsandapplicabilitytoparticularwindfarms.

To minimise costs, the construction process for gravity bases must be simplified and achieve high repeatability; a challenge well within the scope and potential of concrete construction. A number of port locations have been identified as potential sites for the construction of gravity base foundations. These potential sites are strategically located around the UK, minimising transportation of the pre-constructed foundations and cutting costs and time.

Additionally, a number of port operators are endeavouring to create global offshore wind hubs which would provide a focus for the industry and facilitate the construction of foundations, turbines and blades in a single location. At least four such hubs need to be established to service the needs of the industry.

The design criteria for offshore wind energy foundations and towers are extremely demanding. The harsh conditions encountered offshore, together with increasing requirements from turbine manufacturers, need to be taken into consideration in the design of the foundations. Concrete, being an extremely versatile material, is able to meet and exceed these demands; thus enabling designs to be future-proofed and allow turbine upgrades when required.

A summary of the design drivers to be considered includes:

� Ground conditions and water depths.

� Size of turbines and rotors.

� Appropriate materials and design details for aggressive marine conditions and storm loadings creating cyclical loading on the tower structure.

� Fatigue effects due to blade rotation with wave loading.

� Simplicity in design concept, and economic construction.

� Minimised weather-dependency during construction and installation.

� Low maintenance, and ease of decommissioning and eventual removal.

� Full installation requirements and availability of the required lifting equipment.

� High repeatability production for maximum economy.

� Future-proof by allowance for future turbine upgrade.

For additional details on the design requirements for an offshore wind energy pylon, refer to The Concrete Centre publication Concrete Towers for Onshore and Offshore Wind Farms – Conceptual design studies atwww.concretecentre.com/publications.

SummaryThe UK wind industry is demanding cost-effective, robust and durable solutions for the next generation of wind energy foundations and pylons.

Overall heights in excess of 100m are required to seat ever more powerful turbines - with capacities of 5MW typical.

Concrete is able to provide a variety of economic solutions for these foundations and towers; readily adaptable to meet specific wind farm

requirements.

References

1. For further information visit the University of Cambridge,

Department of Engineering website (www.eng.cam.ac.uk)

2. For further information visit the Mecal website (www.mecal.nl)

3. An Initial Study Into The Feasibility Of Concrete Pylons For Large

Offshore Wind Energy Converters, The Concrete Centre, October 2004

4. Concrete Credentials: Sustainability, The Concrete Centre, 2010

5. An Estimate of the Embodied CO2 in Steel and Concrete Wind

Turbine Towers, The Concrete Centre, September 2005

All advice or information from MPA -The Concrete Centre is intended only for use in the UK by those who will evaluate the significance and limitations of its contents and take responsibility for its use and application. No liability (including that for negligence) for any loss resulting from such advice or information is accepted by Mineral Products Association or its subcontractors, suppliers or advisors. Readers should note that the publications from MPA - The Concrete Centre are subject to revision from time to time and should therefore ensure that they are in possession of the latest version.

Printed onto 9Lives silk comprising 55% recycled fibre with 45% ECF virgin fibre. Certified by the Forest Stewardship Council.

The Concrete Centre,

Riverside House,

4 Meadows Business Park,

Station Approach, Blackwater,

Camberley, Surrey GU17 9AB

Ref. TCC/02/10

ISBN 978-1-904818-97-7

First published 2010

© MPA - The Concrete Centre 2010

The Concrete Centre is part of the Mineral

Products Association, the trade association for the

aggregates, asphalt, cement, concrete, lime, mortar

and silica sand industries.

www.mineralproducts.org

www.concretecentre.com

MB Concrete Solutions Wind Towers Nov10

Documents

offshore wind farm development

wind towers

offshore development

uk wind industry

wind tower projects

wind energy pylons

development zones

concrete gravity bases