JUNE/JULY 2013 | £5.25 - Wind Energy Network

developments in foundation technologydevelopments in foundation technologyHonorary degrees forthe demands of Round 3 Wind Farmsindustry leadersConcrete Gravity Foundations can meetThe Round 3 sites, leases for whichhave been awarded by The CrownEstate, are much further fromshore and in considerably deeperwaters than the earlier wind farmdevelopments. Hence the locationand depth of the sites provide aconsiderable challenge to developers.This challenge requires the adoptionof alternative solutions as the systemsthat have been utilised up to nowin relatively shallow waters, are notsuitable for these new sites.Gravity foundations, concrete shells thatare placed on the sea bed and thenballasted, provide the engineering solutionto enable the Round 3 developmentsto be successfully constructed. Thebenefits of concrete gravity foundationsfor the water depths under consideration,20m to 50m, are that they are extremelydurable and provide a solution whichis both economic to build and deliversconsiderably reduced maintenance overthe life of the structure. Additionally thesefoundations are placed on the sea bed,thus eliminating the environmental issuesassociated with piling.Part of the solutionThe design, construction and installationof the bases is all part of the solutionthat is offered to developers. In additionmaintenance and removal processeshave all been taken into considerationin the development of gravity basesolutions. The solutions offered areeither self-buoyant, where conventionalvessels are needed for the transportationprocess, or are buoyancy assisted wherea customised vessel is required to assistwith transportation and installation. In bothcases the foundation is ballasted, once inposition, with sand or gravel which ideallywould be available from a nearby location.A little help please…At present I am a second year PhDstudent at Leeds University BusinessSchool studying Logistics andSupply Chain, with a particular focuson the UK offshore wind industry.I graduated from Hull UniversityBusiness School in 2011 with anMSc in Logistics and Supply ChainManagement.PhD focusMy PhD focuses on the strategic reductionof offshore wind supply chain costs. Itaims to identify cost structures in theindustry, track down the major cost driversand discover links between supply chainmanagement practices and the costincreases.concrete gravity foundationmanufacturers co-locating onport facilities in the North Eastof England.The aim is to reduce totaldelivered costs of foundationsthrough…• Minimising movements ofmaterials and products• Minimising the number of timesmaterials and products are handled• Reducing the number of individualmaterials and product storagelocations• Reducing the logistics costs ofmaterials, products and peopleConcrete Centre interest groupinitiativeThe contractors within the interestgroup have designed and developedsystems which enable the foundationsto be launched, transported to siteand then installed with the minimumof potential downtime due to theadverse weather conditions. They haveplanned facilities which will enable thesimultaneous construction of multiplefoundations, similar to concepts adoptedfor car production. This application ofmanufacturing efficiencies will help deliverthe cost savings that the government,energy providers and energy users arehoping for from renewable energy.Positive responseThere is no doubt that the challengesof Round 3 will require both innovativesolutions and a full commitment from thewhole of the associated supply chain. Theconcrete industry through the interest grouphas shown that it has responded positivelyto these challenges and is ready to deliver.The Concrete Centrewww.concretecentre.comClick to view more infoIn building this dynamicperspective and incontrast to other formsof data collection thatfail to fully understandwhy issues occur, thestronger the level ofparticipation the strongerthe knowledge base willbe, allowing me to betterarticulate and fully forma coherent case that willoutline key areas for costreduction in the industry.I am now seeking collaboration with majorOEMs, 1st – 3rd tier suppliers, and UKenterprises. Can you help me?Patrick HennellyInnovativegravity basefoundationthroughteamworkRoyal BAM Group and Van OordOffshore Wind projects have teamedup to design, manufacture and installreinforced concrete gravity basefoundations (GBFs) for the offshorewind industry.ExperienceThe innovative hybrid concept for the GBFhas been developed using BAM and VanOord’s wide experience of designing andconstructing immersed tube tunnels andgravity base structures. The basic GBFsolution has been specifically designedfor deep water applications and hasundergone model testing. It is adaptableto suit a range of water depths, waveheights and sea bed conditions.Self-buoyantThe GBF is designed to be mass producedonshore in a quayside construction yardusing BAM’s core skills in reinforcedconcrete construction. Beingself-buoyant, it is then towedout to sea using standard oceangoing tugs.Marine worksOnce in position the GBF issubmerged under closelycontrolled conditions on apre-prepared sea bed. Rockarmour is then placed aroundthe base to afford protectionagainst scour and the structureis ballasted with sand. All marineworks are carried out by VanOord using vessels from theirown fleet. The GBF structureis then ready to receive thetransition shaft and turbine,mounted on the central shaft.AdvantagesThe hybrid solution has many advantages,including…• Adaptability to a wide range ofmetocean conditions and turbineloadings• Low centre of gravity, giving goodstability when towing• Towed into position using standardtugs, obviating the need for costlyspecialist vessels• Simple steel to steel connectionbetween shaft and transition piece tothe turbine• NDV design certification achieved forthe concept• All required vessels available withinVan Oord’s fleet• Short weather window required forinstallation• Competitive cost• High use of local materials and locallabourRoyal BAM Groupwww.bam.euVan Oord Offshore Windwww.vanoord.comCentral to my research is understandingand developing buyer-supplierrelationships, in particular, from thesupplier’s perspective.Concrete gravity foundationsI am currently working on a projectthat aims to assess the benefits forEngagement with the industryMy research engages with issues that arerelevant to the UK offshore wind supplychain. The tools utilised throughout myresearch focus on capturing and buildingcurrent and dynamic perspectives throughdirect engagement with key stakeholdersin the industry.Ed’s NotePlease email our editorduncan@greenenergypublishing.co.ukand we will pass your contact detailson to Patrick. In helping him we aresure you will be helping the industry.38 www.windenergynetwork.co.ukwww.windenergynetwork.co.uk 39