Station keeping analysis and design for new floating offshore wind turbines

In the framework of the reduction of the emissions of greenhouse gases, FOWT will be the technology that will exploit the wind resources in deep seas. In order to achieve a commercial deployment of this technology, a cost reduction is necessary through the optimization of the wind turbine by detailed studies to reduce its design uncertainties. One important aspect is the mooring system, which commonly represents between a 10 to 15 % of the capex. The present research aims to increase the knowledge of the design and analysis of the station keeping systems for floating offshore wind turbines. One of the most important aspects for a correct analysis and design of the mooring system is the simulation of the lines coupled with the floating structure and the wind turbine. In this dissertation, two different mooring line models coupled to a finite element model for the analysis of floating platforms are presented. The first model is a finite element model based on a slender rod approach. The model is extended to consider the rheological damping in the axial and bending direction within the constitutive equations of the problem. The second model is a new approach named quasi-dynamic model. The model assesses the static solution of the catenary equation but updates the line tension based on the external hydrodynamic forces and the inertial forces from the theoretical motion of the mooring line. In the design of mooring lines is important to consider and foresee the different phenomena and loads that can act along on the life span of these elements. Within these phenomena, the effects of the waves forces over the mooring lines o have been studied. The study analyzes the contribution of the wave forces over the mooring lines to determine when it is an important source of damage for the fatigue strength. Finally, new floating platform concepts need to be tested and analyzed in controlled conditions in order to validate the models used for the final designs. It is common that pool and flume basins do not present enough size for the catenary shape mooring systems because they cover a large extension. In this area, an optimization model for a truncated mooring system is presented. The truncated mooring system is formed by two types of chains to emulate the actual prototype mooring system of a scale spar platform in a narrow flume.En el marc de la reducció de les emissions de gasos d’efecte hivernacle, l’energia eòlica marina flotant serà la tecnologia que explotarà els recursos eòlics marins a gran profunditat. Per tal d’aconseguir un desenvolupament a escala comercial d’aquesta tecnologia és necessari una reducció dels costos a través de l’optimització dels aerogeneradors a partir d’estudis i anàlisis molt detallats. Un dels aspectes importants és el sistema d’amarratge, el qual pot representar entre un 10 i 15 % del cost total d’una instal·lació. La present recerca aprofundeix en el disseny i anàlisis dels sistemes d’amarratge per a molins de vent flotant. Un dels aspectes més importants per a al correcte disseny i anàlisis dels sistemes d’amarratge és la simulació de les amarres conjuntament amb el sistema flotant. En aquesta dissertació es presenten dos models d’amarres diferents acoblats a un model d’elements finits per a l’anàlisi d’estructures flotants. El primer model, és un model d’elements finits per a línies d’amarres basat en un model de vareta esvelta. El model s’ha ampliat per tenir en compte l’esmorteïment material degut als esforços en les direccions axial i de flexió dins de les equacions constitutives dels problema. El segon model es tracta d’un model quasi-dinàmic, el qual es basa en la solució estàtica de les amarres però actualitza la tensió de l’amarra en funció de les forces inercials i hidrodinàmiques externes calculades a partir del moviment teòric de l’amarra. En el disseny de les amarres també s’ha de tenir en compte i preveure els diferents fenòmens i accions que poden influir en la vida útil d’aquests elements. Dins d’aquests fenòmens, s’ha aprofundit en l’anàlisi dels efectes de les forces de l’onatge sobre les amarres. En aquest sentit es fa una comparació entre la consideració o no d’aquestes forces sobre les amarres pe tal de determinar en quins casos poden suposar una font important de dany per a la seva resistència a la fatiga. Per últim, els nous conceptes de plataformes flotants s’han d’assajar i analitzar en condicions controlades per tal de validar els models utilitzats en el disseny final. És freqüent que les piscines i canals d’assaig no presentin les dimensions adequades per a l’experimentació dels sistemes d’amarres ja que poden ocupar una gran extensió d’espai. En aquest àmbit es presenta un model d’optimització d’unes amarres truncades formades per dos tipus de cadena diferents per tal d’emular el disseny d’amarres del prototip a escala real.Postprint (published version

Construction possibilities for monolithic concrete spar buoy serial production

The monolithic nature of Windcrete, that sees floater, transition piece and tower as a single concrete structure, has direct impact on its potential construction process. The large-draft spar-buoy, to be fully completed in a coastal facility, requires horizontal transport that prompts construction also to be done horizontally. Then, the constraints to produce Windcrete structures are: large concrete structure built in horizontal position, preferably in a single monolithic pour with high quality standards, and this within reasonable production time if the project is considered at commercial deployment stage. In search for an appropriate solution, proposals will seek inspiration from a variety of engineering fields: mechanized tunnelling practices, farreaching adaptations of slip-forming, reinforced centrifugal concrete pipe production and even trenchless technologies such as pipe jacking will all serve as a basis to elaborate a series of tailored solutions compatible with the specific requirements of Windcrete.Postprint (published version

Procediments constructius i materials per a estructures off-shore. Aplicació a aerogeneradors

[ANGLÈS] In this minor thesis a research on different installation methods of marine structures has been done in order to propose the installation process of a SPAR floating wind platform. Nowadays offshore technology is mainly founded on building petrol platforms to get crude. The prototypes of the floating wind platforms are based on offshore platforms but on a smaller scale. This is the reason why the installation process must be reformulated to be more efficient and economical, always checking the integrity of the structure. The main studies carried out in this dissertation are the transport settings of the structure and its erection. The structure during transport is submitted to different conditions from its final work configuration, therefore the possible effects it can suffer during the operation have been studied. The buoyancy of the structure in the transport position has been studied too. Also, the stress that the structure has to support, the elements which are necessary to transport and the tugs that are required to carry out this operation have been checked. As the transportation is in horizontal position, the most important operation is the erection process and it has to be very detailed. This thesis proposes carrying out the erection by ballasting seawater inside the structure that helps the rotation without external mechanical elements. In this section, also a thorough study has been made to ensure the integrity of the structure, to guarantee that the structure is not damaged during the process and to control the tensions that it has to support. Based on the results, it is proposed the main phases that are necessary to install a SPAR floating wind platform and to ensure a proper set up without any risk situations that could damage the structure.[CATALÀ] En aquesta tesina s’ha realitzat una recerca dels diferents mètodes d’instal·lació de les estructures marines per tal de proposar el procés d’instal·lació d’un aerogenerador marí flotant tipus SPAR. La tecnologia offshore que existeix actualment es basa principalment en la construcció de plataformes petrolíferes per a l’obtenció del cru. Les tipologies estructurals dels prototips d’aerogeneradors flotants actuals es basen en la tecnologia de les plataformes petrolíferes però en una escala més petita. És per aquest motiu que els processos d’instal·lació s’han de reformular per tal de plantejar una manera més eficient i econòmica, controlant sempre la integritat de l’estructura. Els estudis principals que s’han dut a terme han estat les configuracions de l’estructura durant el transport d’aquesta i la seva erecció. Durant el transport l’estructura es troba en unes condicions que no són les configuracions finals de treball i per tant s’ha estudiat els possibles efectes que pot tenir. S’ha estudiat la flotabilitat de l’estructura en la posició de transport. Per altra banda s’han comprovat els esforços als quals es veu sotmesa l’estructura i quins elements són necessaris per al transport i els remolcs que siguin necessaris per dur a terme aquesta operació. Al transportar l’estructura en posició horitzontal l’operació més important i que cal tenir ben detallada és el procés d’erecció d’aquesta. En aquesta tesina s’ha proposat realitzar el procés d’erecció de l’estructura de l’aerogenerador per mitjà del llastrament d’aigua marina dins de l’estructura que afavoreixi el moviment d’erecció per tal de disposar dels mínims elements mecànics externs possibles. En aquest apartat també s’ha fet un estudi exhaustiu de l’operació per tal d’assegurar la seva integritat, que no sofreixi danys durant aquest procés i un control dels esforços que ha de suportar. En base als resultats obtinguts s’han proposat les principals fases que s’hauran de dur a terme per tal d’instal·lar una estructura d’un aerogenerador marí flotant del tipus SPAR i per assegurar la seva correcta posada en servei sense que es puguin produir situacions que siguin un risc i puguin malmetre l’estructura

Validation of numerical models of the offshore wind turbine from the alpha ventus wind farm against full-scale measurements within OC5 Phase III

The main objective of the Offshore Code Comparison Collaboration Continuation, with Correlation (OC5) project is validation of aero-hydro-servo-elastic simulation tools for offshore wind turbines (OWTs) through comparison of simulated results to the response data of physical systems. Phase III of the OC5 project validates OWT models against the measurements recorded on a Senvion 5M wind turbine supported by the OWEC Quattropod from the alpha ventus offshore wind farm. The following operating conditions of the wind turbine were chosen for the validation: (1) idling below the cut-in wind speed, (2) rotor-nacelle assembly (RNA) rotation maneuver below the cut-in wind speed, (3) power production below and above the rated wind speed, and (4) shutdown. A number of validation load cases were defined based on these operating conditions. The following measurements were used for validation: (1) strains and accelerations recorded on the support structure and (2) pitch, yaw, and azimuth angles, generator speed, and electrical power recorded from the RNA. Strains were not directly available from the majority of the OWT simulation tools; therefore, strains were calculated based on out-of-plane bending moments, axial forces, and cross-sectional properties of the structural members. The simulation results and measurements were compared in terms of time series, discrete Fourier transforms, power spectral densities, and probability density functions of strains and accelerometers. A good match was achieved between the measurements and models setup by OC5 Phase III participants.OWEC Tower is acknowledged for releasing the jacket substructure, transition piece, and foundation design data for Phase III. Senvion is acknowledged for sharing the definition of the Senvion 5M wind turbine and its tower. The RAVE consortium is acknowledged for releasing the measurement data from the alpha ventus wind farm. This work was authored (in part) by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding provided by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Wind Energy Technologies Office. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan. http://energy.gov/downloads/doe-public-accessplanPeer ReviewedWojciech Popko / Fraunhofer IWES, Fraunhofer Institute for Wind Energy Systems / , Division Wind Turbine and System Technology, Am Luneort 100, Bremerhaven 27572 / , Germany / Amy Robertson / National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 / Jason Jonkman / National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 / Fabian Wendt / National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 / Philipp Thomas / Fraunhofer IWES, Fraunhofer Institute for Wind Energy Systems / , Division Wind Turbine and System Technology, Am Luneort 100, Bremerhaven 27572 / , Germany / Kolja Müller / University of Stuttgart / , Allmandring 5b, Stuttgart Wind Energy, Stuttgart 70569 / , Germany / Matthias Kretschmer / University of Stuttgart / , Allmandring 5b, Stuttgart Wind Energy, Stuttgart 70569 / , Germany / Torbjørn Ruud Hagen / OWEC Tower AS, Sommerrogata 17, Oslo 0255 / , Norway / Christos Galinos / Technical University of Denmark / , Department of Wind Energy, Frederiksborgvej 399, Roskilde 4000 / , Denmark / Jean-Baptiste Le Dreff / Electricitéde France, Recherche et Développement, 13 Boulevard Gaspard Monge, Palaiseau 91120 / , France / Philippe Gilbert / IFP Energies Nouvelles, 1 et 4 avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex / , France / Bertrand Auriac / Principia La Ciotat, 215 Voie Ariane, La Ciotat 13600 / , France / Sho Oh / Nippon Kaiji Kyokai (ClassNK), 4-7 Kioicho, Chiyoda-Ku, Tokyo 102-8567 / , Japan / Jacob Qvist / 4Subsea, Hagaløkkveien 26, 1383 Asker, Hvalstad / , Norway / Stian Høegh Sørum / Norwegian University of Science and Technology / , Department of Marine Technology, Trondheim 7491 / , Norway / Loup Suja-Thauvin / Simis AS, Leonardveien 3, Malm 7790 / , Norway / Hyunkyoung Shin / University of Ulsan / , School of Naval Architecture and Ocean Engineering, Ulsan / , South Korea / Climent Molins / Polytechnic University of Catalonia / , Campus Nord, Carrer de Jordi Girona, 1, 3, Barcelona 08034 / , Spain / Pau Trubat / Polytechnic University of Catalonia / , Campus Nord, Carrer de Jordi Girona, 1, 3, Barcelona 08034 / , Spain / Paul Bonnet / Siemens Industry Software, Luis, Carrer Lluís Muntadas, No. 5, Cornellà de Llobregat, Barcelona 08940 / , Spain / Roger Bergua / Envision Energy Limited, 8/F, Building B, SOHO Zhongshan Plaza, 1065 West Zhongshan Road, Shanghai 200051 / , China / Kai Wang / Envision Energy Limited, 8/F, Building B, SOHO Zhongshan Plaza, 1065 West Zhongshan Road, Shanghai 200051 / , China / Pengcheng Fu / China General Certification Center, Room 1108, Yiheng Building No. 28, North 3rd Ring Road East, Chaoyang District, Beijing 100013 / , China / Jifeng Cai / China General Certification Center, Room 1108, Yiheng Building No. 28, North 3rd Ring Road East, Chaoyang District, Beijing 100013 / , China / Zhisong Cai / China General Certification Center, Room 1108, Yiheng Building No. 28, North 3rd Ring Road East, Chaoyang District, Beijing 100013 / , China / Armando Alexandre / DNV GL, One Linear Park, Avon Street, Temple Quay, Bristol BS2 0PS / , UK / Robert Harries / DNV GL, Edificio Trovador, Plaza de Antonio Beltrán Martínez, Zaragoza 50002 / , SpainPostprint (published version

Implantació d’un SIG a Chefchafeu

Implantació d’un SIG a Chefchafeu te un objectiu general molt clar, construir una eina que permeti identificar i gestionar elements arquitectònics tradicionals de la medina de Chefchauen, municipi i ciutat del Marroc situada al nord-oest del país, per tal de realitzar anàlisis i obtenir conclusions per possibles intervencions. Desglossant l’objectiu global, el projecte es divideix en cinc parts. La primera és la unificació de criteris per a la gestió dels elements d’interès arquitectònic que destaquen al paisatge urbà de la medina. Potser la part més creativa, consisteix en analitzar tota la informació per tal de reduir-la i transformar-la en un format de base de dades. El següent pas és fer el disseny d’aquesta. La segona part recau en la recopilació d’informació per la seva posterior organització. Treball de camp realitzat in situ durant tres setmanes al Novembre de 2012. Un cop obtinguda tota la informació el tercer objectiu consisteix en introduir-la en un Sistema Informàtic Goreferenciat, l’ArcGIS. Aquesta eina permetrà realitzar una gestió eficient que relacionarà cada element arquitectònic amb la informació que d’ell es disposa. Seguidament s’importa aquesta base de dades al software PostgreSQL/PostGIS que servirà de suport a l’últim objectiu. Crear una pàgina web que contingui les suficients eines per fer consultes a la base de dades, un visor que mostri els resultats, és a dir els polígons dels elements estudiats en un mapa i una finestra amb la fitxa tècnica en format pdf de cada un d’ells

Nutrient status and transplant shock on Mediterranean shrubs under semiarid climate

Hemos utilizado diferentes regímenes de fertirrigación en vivero y fertilizante de liberación lenta para producir brinzales de cinco especies leñosas mediterráneas (Pistacia lentiscus, Quercus coccifera, Rhamnus lycioides, Rhamnus alaternus, Tetraclinis articulata) con características morfológicas y funcionales contrastadas, y hemos evaluado el efecto de estos tratamientos sobre la vitalidad (potencial de crecimiento de raíces) y comportamiento en el campo (supervivencia tras el shock de transplante). El tamaño de los brinzales varió sustancialmente con los tratamientos. Observamos una relación positiva entre el estado nutricional y el crecimiento potencial de raíces, relación que era consecuencia del tamaño de las plantas. Las deficiencias de nitrógeno y fósforo, la reducción de la dosis de nutrientes o el endurecimiento por reducción de la proporción de N en las últimas fases de cultivo en vivero favorecieron la supervivencia de los brinzales a corto plazo. No observamos relación positiva entre el crecimiento potencial de raíces y la resistencia al shock post-transplante. Estos resultados contrastan con los obtenidos en zonas con déficit hídrico menos acusado.We have analyzed the effect of different fertilizer types and doses on the morphology and performance of five semiarid shrubs commonly used in afforestation programmes. Species selected had contrasted morpho-functional traits: Pistacia lentiscus, Quercus coccifera, Rhamnus lycioides, Rhamnus alaternus, Tetraclinis articulata. We found a relationship between application regime and root growth potential (RGP). Most of the variation in RGP was explained by seedling size, suggesting that other effects of nutrient application were less important. Short-term mortality reduced by nitrogen and phosphorus deficiency and nutrient hardening. No positive relationship was observed between RGP and transplant shock. Results contrast with works carried out in sub-humid areas.Este trabajo ha sido financiado por CEAM-Fundación Bancaja y una beca de investigación concedida a R. Trubat en el marco del proyecto CREOAK

Experiments on a scale model of a monolithic concrete spar for floating wind turbines

Preliminary studies of a concept consisting of a monolithic concrete SPAR platform were presented in 2014. The studies were performed in the framework of the AFOSP KIC-InnoEnergy project (Alternative Floating Platform Designs for Offshore Wind Towers using Low Cost Materials) showing significant costs reduction. The experimental phase of the project was developed during 2014. The experiments comprised a set of hydrodynamic tests performed in the CIEM wave flume facility at the Universitat Politècnica de Catalunya (UPC), with a 1:100 scale model assuming Froude similitude. The complete experimental campaign included free decay tests, a set of 22 regular wave trains of different periods to determine the RAO’s and another set of 21 regular and irregular wave trains in conjunction with a mechanical wind device, simulating the mean thrust force exerted by the wind turbine. To adjust the weight of the whole system, a set of adjustable weights inside de scale model were designed assuring such properties, particularly the pitch/roll inertia. The scaled model of the mooring system was carefully studied because the constraints in width of the flume facility. A mechanical wind device was also specifically designed to ensure an averaged force at the top of the model, simulating the effect of the mean rotor thrust force. A detailed description of the methodology for the experimental campaign and a summary of the experimental results are presented.Peer ReviewedPostprint (author’s final draft

OC6 project Phase III: validation of the aerodynamic loading on a wind turbine rotor undergoing large motion caused by a floating support structure

This paper provides a summary of the work done within Phase III of the Offshore Code Comparison Collaboration, Continued, with Correlation and unCertainty (OC6) project, under the International Energy Agency Wind Technology Collaboration Programme Task 30. This phase focused on validating the aerodynamic loading on a wind turbine rotor undergoing large motion caused by a floating support structure. Numerical models of the Technical University of Denmark 10¿MW reference wind turbine were validated using measurement data from a 1:75 scale test performed during the UNsteady Aerodynamics for FLOating Wind (UNAFLOW) project and a follow-on experimental campaign, both performed at the Politecnico di Milano wind tunnel. Validation of the models was performed by comparing the loads for steady (fixed platform) and unsteady (harmonic motion of the platform) wind conditions. For the unsteady wind conditions, the platform was forced to oscillate in the surge and pitch directions under several frequencies and amplitudes. These oscillations result in a wind variation that impacts the rotor loads (e.g., thrust and torque). For the conditions studied in these tests, the system aerodynamic response was almost steady. Only a small hysteresis in airfoil performance undergoing angle of attack variations in attached flow was observed. During the experiments, the rotor speed and blade pitch angle were held constant. However, in real wind turbine operating conditions, the surge and pitch variations would result in rotor speed variations and/or blade pitch actuations, depending on the wind turbine controller region that the system is operating. Additional simulations with these control parameters were conducted to verify the fidelity of different models. Participant results showed, in general, a good agreement with the experimental measurements and the need to account for dynamic inflow when there are changes in the flow conditions due to the rotor speed variations or blade pitch actuations in response to surge and pitch motion. Numerical models not accounting for dynamic inflow effects predicted rotor loads that were 9¿% lower in amplitude during rotor speed variations and 18¿% higher in amplitude during blade pitch actuations.This research has been supported by the office of Energy Efficiency and Renewable Energy (grant no. DE-AC36-08GO28308).Peer ReviewedRoger Bergua1, Amy Robertson1, Jason Jonkman1, Emmanuel Branlard1, Alessandro Fontanella2, Marco Belloli2, Paolo Schito2, Alberto Zasso2, Giacomo Persico3, Andrea Sanvito3, Ervin Amet4, Cédric Brun5, Guillén Campaña-Alonso6, Raquel Martín-San-Román6, Ruolin Cai7, Jifeng Cai7, Quan Qian8, Wen Maoshi8, Alec Beardsell9, Georg Pirrung10, Néstor Ramos-García10, Wei Shi11, Jie Fu11, Rémi Corniglion12, Anaïs Lovera12, Josean Galván13, Tor Anders Nygaard14, Carlos Renan dos Santos14, Philippe Gilbert15, Pierre-Antoine Joulin15, Frédéric Blondel15, Eelco Frickel16, Peng Chen17, Zhiqiang Hu17, Ronan Boisard18, Kutay Yilmazlar19, Alessandro Croce19, Violette Harnois20, Lijun Zhang21, Ye Li21, Ander Aristondo22, Iñigo Mendikoa Alonso22, Simone Mancini23, Koen Boorsma23, Feike Savenije23, David Marten24, Rodrigo Soto-Valle24, Christian W. Schulz25, Stefan Netzband25, Alessandro Bianchini26, Francesco Papi26, Stefano Cioni26, Pau Trubat27, Daniel Alarcon27, Climent Molins27, Marion Cormier28, Konstantin Brüker28, Thorsten Lutz28, Qing Xiao29, Zhongsheng Deng29, Florence Haudin30, and Akhilesh Goveas31 1National Wind Technology Center, National Renewable Energy Laboratory, Golden, CO 80401, USA 2Department of Mechanical Engineering, Politecnico di Milano, Milan 20156, Italy 3Laboratory of Fluid-Machines, Dipartimento di Energia, Politecnico di Milano, Milan 20156, Italy 4Wind Department, Bureau Veritas, Paris 92937, France 5Marine Division, Research Department, Bureau Veritas, Saint-Herblain 44818, France 6Wind Turbine Technologies, Centro Nacional de Energías Renovables, Sarriguren 31621, Spain 7Integrated Simulation Department, China General Certification Center, Beijing 100013, China 8Research Institute, China State Shipbuilding Corporation, Chongqing 401122, China 9Offshore Technology Department, DNV, Bristol BS2 0PS, UK 10Department of Wind Energy, Technical University of Denmark, Lyngby 2800, Denmark 11State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China 12Département Electrotechnique et Mécanique des Structures, Électricité de France, Paris 91120, France 13Wind Energy Department, eureka!, Errigoiti 48309, Spain 14Department of Wind Energy, Institute for Energy Technology, Kjeller 2027, Norway 15Département Mécanique des Fluides, IFP Energies nouvelles, Rueil-Malmaison 92852, France 16Research and Development, Maritime Research Institute Netherlands, Wageningen 6708, the Netherlands 17Marine, Offshore and Subsea Technology, Newcastle University, Newcastle NE1 7RU, UK 18Aerodynamic Department, Office National d’Etudes et de Recherches Aérospatiales, Paris 92190, France 19Department of Aerospace Science and Technology, Politecnico di Milano, Milan 20156, Italy 20Floating Offshore Group, PRINCIPIA, La Ciotat 13600, France 21Wind Energy Group, Shanghai Jiao Tong University, Shanghai 200240, China 22Department of Offshore Renewable Energy, Tecnalia Research & Innovation, Donostia-San Sebastián 20009, Spain 23Wind Energy Department, Netherlands Organisation for Applied Scientific Research, Petten 1755, the Netherlands 24Wind Energy Department, Technische Universität Berlin, 10623 Berlin, Germany 25Institute for Fluid Dynamics and Ship Theory, Hamburg University of Technology, 21073 Hamburg, Germany 26Department of Industrial Engineering, University of Florence, Florence 50139, ItalyPostprint (published version

The role of ecophysiology in reforestation

La repoblación forestal ha sido la práctica de restauración ecológica a gran escala más extendida en la mayoría de países mediterráneos. El establecimiento de las diferentes especies depende de diversos factores abióticos y bióticos, y entre estos últimos las características morfofuncionales propias de cada especie. Las especies implicadas y la calidad de la planta forestal son factores esenciales en el éxito de las reforestaciones. Hasta hace unos años, los resultados de las reforestaciones se analizaban en un contexto de respuesta en términos de supervivencia y crecimiento de las especies introducidas y su relación con sus características morfológicas. La aparición de equipos de ecofisiología, en mayor o menor medida portátiles, ha permitido incorporar información ecofisiológica en la evaluación de la calidad y el estado de las plantas. De esta forma se ha abierto un amplio abanico para la interpretación de los resultados que contempla desde aspectos puramente morfológicos hasta aspectos que incluyen el funcionamiento de las especies. La ecofisiología puede ser una herramienta muy útil para ayudar a explicar los procesos involucrados en la respuesta de las especies. Dentro de los aspectos ecofisiológicos, el análisis de las estrategias desarrolladas en relación con variables bióticas y abióticas ha sido el campo de investigación que en mayor medida ha aprovechado los avances técnicos y metodológicos en ecofisiología. Desde la comprensión de los diferentes factores que interactúan en una planta, se podrán adecuar las técnicas de vivero para poder manipular las características morfofuncionales de los plantones según los intereses y objetivos de la restauración forestal.Afforestation and reforestation have been the more extended practices of forest restoration in most of Mediterranean countries. The establishment of the different species depends on both abiotic and biotic factors, the later including morphofunctional characteristics of each species. Target species and stock quality of seedlings are two of the main factors influencing reforestation success. Until recently, results of reforestations were analyzed in terms of survival and growth of the introduced species and the relationship of these variables with the morphological characteristics of seedlings. The new developments of ecophysiological instrumentation, with improved portability, have allowed to incorporate ecophysiological information in the assessment of the quality and the performance of seedlings. In this way, new perspectives on functional and morphological evaluation of seedlings have been opened. Ecophysiological techniques can be a very useful tool helping to explain the processes involved in the responses of the species.Within the ecophysiological aspects, the analysis of the strategies developed by species in relation to biotic and abiotic factors has been the more developed field of research. Starting from this point and from the understanding of the different factors that interact in a plant, a deeper knowledge on seedling ecophysiology will help to produce high performance seedlings and we will be able to adapt nursery techniques in order to manipulate morphofunctional characteristic of seedlings according to the interests and objectives of forest restoration.La elaboración de esta revisión ha sido parcialmente financiada por la Generalitat Valenciana, BANCAIXA y los proyectos REDMED (Restoration of Degraded Ecosystems in Mediterranean Regions, ENV4-CT97-0682), CREOAK (Conservation and Restoration of European Cork Oak Woodlands: a Unique Ecosystem in the Balance, QLRT-2001-01594) de la CE y XilRefor (Grupos 155/03) de la Generalitat Valenciana

OC6 Phase II: Integration and verification of a new soil–structure interaction model for offshore wind design

This paper provides a summary of the work done within the OC6 Phase II project, which was focused on the implementation and verification of an advanced soil–structure interaction model for offshore wind system design and analysis. The soil–structure interaction model comes from the REDWIN project and uses an elastoplastic, macroelement model with kinematic hardening, which captures the stiffness and damping characteristics of offshore wind foundations more accurately than more traditional and simplified soil–structure interaction modeling approaches. Participants in the OC6 project integrated this macroelement capability to coupled aero-hydro-servo-elastic offshore wind turbine modeling tools and verified the implementation by comparing simulation results across the modeling tools for an example monopile design. The simulation results were also compared to more traditional soil–structure interaction modeling approaches like apparent fixity, coupled springs, and distributed springs models. The macroelement approach resulted in smaller overall loading in the system due to both shifts in the system frequencies and increased energy dissipation. No validation work was performed, but the macroelement approach has shown increased accuracy within the REDWIN project, resulting in decreased uncertainty in the design. For the monopile design investigated here, that implies a less conservative and thus more cost-effective offshore wind design.US Department of Energy Office of Energy Efficiency and Renewable Energy Wind Energy Technologies Office, Grant/Award Number: DE-AC36-08GO2830