Department of Shipping and Marine Technology CHALMERS UNIVERSITY OF TECHNOLOGY Gothenburg, Sweden 2015 Master Thesis NM-15/46 Challenges of achieving a high accessibility in remote offshore wind farms How will changing operational requirements affect access strategy during the operation and maintenance phase? Master’s Thesis in the Nordic Master’s Programme in Maritime Management CHRISTOPHER ANDERBERG A MASTER THESIS IN THE NORDIC MASTER’S PROGRAME IN MARITIME MANAGEMENT Challenges of achieving a high accessibility in remote offshore wind farms How will changing operational requirements affect access strategy during the operation and maintenance phase? CHRISTOPHER ANDERBERG Department of Shipping and Marine Technology CHALMERS UNIVERSITY OF TECHNOLOGY Gothenburg, Sweden 2015 Challenges of achieving a high accessibility in remote offshore wind farms How will changing operational requirements affect access strategy during the operation and maintenance phase? CHRISTOPHER ANDERBERG © CHRISTOPHER ANDERBERG, 2015 Master Thesis NM-15/46 ISSN 1652-8557 Department of Shipping and Marine Technology Chalmers University of Technology SE-412 96 Gothenburg Sweden Telephone +46 (0)31 772 1000 Cover: Mainprize Offshore Ltd.: The CTV at the Dantysk wind farm (2014) Printed by Chalmers Gothenburg, Sweden 2015 CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 i Challenges of achieving a high accessibility in remote offshore wind farms How will changing operational requirements affect access strategy during the operation and maintenance phase? Master Thesis in the Nordic Master’s Programme in Maritime Management CHRISTOPHER ANDERBERG Department of Shipping and Marine Technology Chalmers University of Technology ABSTRACT The wind offshore industry has experienced a vast development since the start in the early 1990’s. At the end of 2013 there were 117.3 GW of installed wind energy capacity in the EU: 110.7 GW onshore and 6.6 GW offshore. A natural consequence of development offshore is a need for suitable vessels to undertake the assignments that arise from site development, site construction and further on to site operations and maintenance. During the operation & maintenance phase, which involves various support activities to carry out planned or unplanned maintenance, special designated Crew Transfer Vessels (CTV) conduct the majority of these. The tendency for wind offshore is to develop more and larger farms further offshore. There exists a need from many perspectives to develop and optimizing the access systems and the procedures around it in order to meet new operational demands for future wind farms. This thesis main purpose is to investigate how changing operational requirement in remote offshore wind farms will affect the safe and efficient transfer of personnel to wind turbines. To answer this, a qualitative research approach was selected where a mixed methodology was carried out involving on-bard observation on a real wind farm crew transfer vessel and through semi-structured interviews. Two main conclusions were drawn in the study. Firstly, the ambition for a high availability in remote offshore wind farms is crucial for the development and also to defend that push to be attractive in the future. The level of availability is dependent of an acceptable level of accessibility. Far offshore wind farms will require that the operational margins for crew transfer need to be increased in maintaining that. The limitations of the CTV’s can to some extent cover that and still remain safe and efficient, but an increased transfer time will limit that option. Secondly the SOV (Service Offshore Vessel) or other accommodation concept will cover the duties in working in rougher sea conditions however its efficiency in technician distribution needs to be increased if this should remain a cost effective solution. Keywords: Accessibility, access systems, crew transfer vessel, offshore wind, operation and maintenance, offshore wind turbine, service offshore vessel CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 ii TABLE OF CONTENTS ABSTRACT ...................................................................................................................................... i TABLE OF CONTENTS ................................................................................................................. ii PREFERENCE ................................................................................................................................ iv LIST OF ABBREVATIONS ............................................................................................................ v LIST OF FIGURES .......................................................................................................................... v LIST OF TABLES .......................................................................................................................... vi 1 INTRODUCTION ................................................................................................................ 7 History of Wind Power Offshore ..........................................................................................7 Thesis Background ....................................................................................................................7 1.2.1 The European Strategy for the Offshore Wind Sector ...................................................................... 8 1.2.2 Offshore wind industry – trends and potentials ................................................................................... 8 Academic Relevance ..................................................................................................................9 Purpose ..................................................................................................................................... 10 Research questions ................................................................................................................. 10 Limitations ............................................................................................................................... 10 Structure .................................................................................................................................. 10 2 THEORETICAL OVERVIEW ........................................................................................11 Offshore wind farms ............................................................................................................ 11 2.1.1 Wind farm Turbines ..................................................................................................................................... 11 2.1.2 Different phases for offshore wind projects .................................................................................. 11 2.1.3 Accessibility and availability .................................................................................................................... 12 O&M strategies for offshore wind farms ............................................................................ 14 Different Access systems ........................................................................................................ 16 2.3.1 Helicopters........................................................................................................................................................ 17 2.3.2 Accommodation ships or fixed platforms offshore ......................................................................... 17 2.3.3 Direct transfer ................................................................................................................................................. 18 2.3.3.1 Vessel Concepts – Crew Transfer Vessels ..................................................................................... 19 2.3.4 Access methods options .............................................................................................................................. 20 Operational procedures of crew transfer............................................................................ 21 2.4.1 Normal conditions ......................................................................................................................................... 21 2.4.2 Extreme conditions ....................................................................................................................................... 21 2.4.3 Industry procedures and guidelines........................................................................................................ 22 Training and competence ...................................................................................................... 26 HSE – (Health, Safety and Environment) ........................................................................... 26 2.6.1 Incident Reporting ......................................................................................................................................... 27 3 METHODOLOGY .............................................................................................................30 Mixed methods ........................................................................................................................ 30 Grounded theory ..................................................................................................................... 30 Data collection ......................................................................................................................... 30 3.3.1 Interviews.......................................................................................................................................................... 30 3.3.2 Hierarchical Task analysis (HTA) - On-board studies and observations ............................... 31 3.3.3 HTA..................................................................................................................................................................... 32 Ethics ........................................................................................................................................ 33 Data Analysis ........................................................................................................................... 33 3.5.1 Interviews.......................................................................................................................................................... 33 3.5.2 HTA..................................................................................................................................................................... 34 CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 iii 4 RESULTS .............................................................................................................................34 Results from the interview investigation ............................................................................. 35 4.1.1 Challenges for the wind offshore industry .......................................................................................... 35 4.1.2 Near-shore and present situation ............................................................................................................. 36 4.1.3 Remote offshore wind farm and future perspective ........................................................................ 38 Findings from Observations and Task Analysis ................................................................ 40 5 DISCUSSION ......................................................................................................................44 Operational limitations for crew transfer vessels .............................................................. 44 Current access system and procedures ............................................................................... 45 Changing operational requirements in remote offshore wind farms ............................. 46 Development of access systems in remote offshore windfarms ....................................... 47 Methodological considerations ............................................................................................. 49 5.5.1 Written sources ............................................................................................................................................... 49 5.5.2 Interviews.......................................................................................................................................................... 49 5.5.3 On-board observation and HTA .............................................................................................................. 50 5.5.4 Cross-reference HTA and Interviews .................................................................................................... 51 Future Research ...................................................................................................................... 51 6 CONCLUSIONS .................................................................................................................52 7 REFERENCES .......................................................................................................................53 APPENDIX A ..............................................................................................................................56 APPENDIX B ...............................................................................................................................57 APPENDIX C ..............................................................................................................................58 CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 iv PREFERENCE This thesis is a part of the requirements for the master’s degree in Maritime Management at Chalmers University of Technology, Göteborg, and has been carried out at the Division of Maritime Human Factors and Navigation, Department of Shipping and Marine Technology, Chalmers University of Technology between January 2013 and June of 2015. I would like to thank Bob Mainprize from Mainprize Offshore and the crew on the MO1 for their support in conducting the observation and interviews, their assistance has been much appreciated. I would also like to thank Dr Sean McCartan, project leader of the EBDIG project for his support in providing an opportunity to conduct the on-board observation. A special thanks also to the companies and the informants that have taken time to enlighten me in the subject through the interviews. Finally a last thank you to my different supervisors along the way and especially to Fredrik Forsman, his support and guidance along the final period of this thesis was much vital to the outcome. Gothenburg 2015-08-31 Christopher Anderberg CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 v LIST OF ABBREVATIONS DP Dynamic positioning HF Human Factors HTA Hierarchical task analysis STCW Standards of Training, Certification and Watch keeping PTV Personnel Transfer Vessel WFSV Wind Farm Support Vessel CTV Crew Transfer Vessel SOV Service Operation Vessel Hs Significant wave height; defined traditionally as the mean wave height (trough to crest) of the highest third of the waves O&M Operation and Maintenance IMR Inspection, Maintenance and Repair OWT Offshore Wind Turbine UK Round 1 Wind farms in from coastline out to distance of 12 nautical miles UK Round 3 Includes nine zones across the UK with a total capacity of 25GW, including the Dogger Bank HTA Hierarchical Task Analysis NM Nautical Miles RIB Rigid Inflatable Boats IMCA International Marine Contractors Association LIST OF FIGURES Figure 1 – Present status of online, consented and under construction offshore wind farms (EWEA, 2011) ........................................................................................................................................................... 9 Figure 2 – Costs connected to different levels of availability (GL Garrad Hassan, 2013) ....... 14 Figure 3 – Ulstein SX175 with X-Stern; SOV Concept for offshore windfarm (photograph courtesy of Ulstein, 2015) .................................................................................................................................. 18 Figure 4 – Vessel transfer times and reference times over distance to port (Bard & Thalemann, 2011) ................................................................................................................................................. 20 Figure 5 - “6 degrees of freedom”, (Used with permission, 2015) .................................................... 21 Figure 6 – Vessel incident break down (Energy Institute (G9), 2014) ............................................. 28 Figure 7 – Marine operations – incident breakdown (Energy Institute (G9), 2014) ................... 28 Figure 8 – Marine operations – incident area breakdown (Energy Institute (G9), 2015) .......... 29 CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 vi LIST OF TABLES Table 1 –Illustration of level off accessibility (compiled from Van Bussel & Bierbooms, 2003) .......................................................................................................................................................................... 13 Table 2 – Different level of accessibility for two different farms (compiled from Salzman, 2007) .......................................................................................................................................................................... 13 Table 3 – Different access systems (compiled from Knudsen C et al, 2011)................................. 17 Table 4 – Reported incident activity (Compiled from the Energy Institute (G9), November 2014) .......................................................................................................................................................................... 27 CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 7 1 INTRODUCTION This chapter contains an introduction to the wind offshore area and the thesis main background; it also covers the thesis main objective, academic relevance, scope and limitations and finally the structure of the study. History of Wind Power Offshore The use of wind to produce electricity began in Scotland in 1891, where James Blyth demonstrated by the use of a vertical-axis wind turbine the ability to transform wind power into electricity in a limited scale. It was not until 1970s that a stronger development took place of onshore wind turbines in Europe and in the United States (MacAskill & Mitchell, 2013). Onshore wind has gone through a great development, however the industry has experienced complications which has limited its growth. Often has this been driven by visual intrusion and noise complaints. The interests have then turned to offshore where these complications were not of any public concern and even the energy potentials have been considered as larger. The development started in Sweden in 1991 where the first wind power unit was installed outside Nogersund and the first offshore wind farm was installed outside Vindeby, Denmark with 11 turbines producing 450 kW each. (MacAskill & Mitchell, 2013). The first “utility-scale” project was developed in Danish waters in 2001, where 20 turbines with a total capacity of 40 MW became operational. Since 2001, where 50,5MW of installed offshore capacity represented 1 % of the total European wind capacity, the development of total capacity have increased annually. At the end of 2013 there were 117.3 GW of installed wind energy capacity in the EU: 110.7 GW onshore and 6.6 GW offshore (EWEA, 2014). The main development has been seen in the European area connected to the North Sea and the Baltic Sea however other areas are under development in countries like United States, Canada, South Korea, Taiwan and China (MacAskill & Mitchell, 2013) Thesis Background A natural consequence of development offshore is a need for suitable vessels to undertake the assignments that arise from site development, site construction and further on to site operations and maintenance. Depending on the requirements in the operations these needs vary from basic generic vessels to purpose built vessels, designed for specific installations tasks. Given the expected forecasted development in the European offshore wind energy market within the next ten to twenty years, the demands on the involved vessels will increase (EWEA, 2011,) This thesis will focus on the sequence involving O&M duties; these activities often involve the transport of technicians and their equipment to and from the site for IMR (Inspection, maintenance and Repair) duties. Traditionally 12 passenger workboats have been used for these operations. Since the ambition of wind farm development is to go further out at sea, longer travel distances or response time might require needs for different vessel concepts and other methods than traditional work boat solution. For example helicopters are becoming more important to use for accessing the turbines, other concepts involves “Hotel-ships” and different kinds of accommodation units for larger and more remote wind farms. MacAskill and Mitchell (2013) also highlights the challenges in remote areas as a key driver to find solutions that could encounter rougher weather conditions, longer transfer time and at CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 8 the same time are cost effective. A necessity for an offshore wind farm is to maintain low down times during the operational phase in order to have it cost effective. Getting the technicians to the farms for their duties, the access system and the procedures around are often seen as the key in securing these in a safe and effective way. The majority of offshore wind farms today are often located less than 25km offshore in relatively calm operational conditions and normally consist of about a 100 wind turbines. Normal duties concerning maintenance and inspection is possible through the use of CTV (Crew Transfer vessels) or by other workboats operating from a nearby port. These operations consists of 90 % of the time when the wave heights are up to about 1,5 m significant (Hs) limit and with an accessibility for around 300 days a year ( Carbon Thrust, 2013). New planned wind farm projects offshore for the UK round 3 sites for example have an average distance to shore of 65 km(35 NM), these farms will encounter much rougher conditions and may consist of 600 turbines. With the status and operational capability of today’s access systems and procedure, this will only allow accessibility for about 210 days a year in 1,5m Hs and that is far too low to keep a farm operational. Increasing the wave height limit to 3.0m Hs will allow an accessibility of 310 days a year (Costa, 2013). There exists a need from many perspectives to develop and optimize the access systems and the procedures around it in order to meet new operational demands for future wind farms. The number of wind farm support vessels has grown and in this emerging fleet the concept of a safe transfer of personnel to the wind turbine unit is the most important objective. It must be done in a safe and efficient manner through certain access points or boat landings. General practise within the industry has been to “butt” the CTV tightly against friction bars on the wind turbine and hold it there with forward propulsion (Marsh, 2013). 1.2.1 The European Strategy for the Offshore Wind Sector The target of the European Wind Energy Association (EWEA) is to reach 230 GW of installed wind power in Europe at the end of 2020, 40 GW of these should come from Wind farms offshore (Besnard et al, 2013). This aligns with the European strategy for renewable energy and in the spring of 2007 the Council of Ministers agreed on ’20:20:20’ goals, the intention is to cut greenhouse gases emissions by 20 % from the 1990 levels, improve energy efficiency by 20 %, and secure 20 % of Europe’s energy demand from renewable sources – all by 2020(Carbon Thrust, 2013). The European commission predicts with reference to year 2013, a slightly lower demand compared to previous predictions from 2009. The forecast predicts 204 GW and offshore winds stands for almost 48 GW. The reason for reduced prognosis is due to the economic downturn in Europe. This has affected investment plans, new orders, investment decisions already taken, and existing installations in markets across Europe both onshore and offshore (EWEA, 2014) 1.2.2 Offshore wind industry – trends and potentials The expected tendency for offshore wind farm development is to go deeper, bigger and further out at sea. The new Dogger Bank project “Dogger Bank Creyke Beck” that was announced in early 2015, has a total generating capacity of 2.4 GW through two different wind farms containing around 400 turbines. This demonstrates the new potentials for far offshore wind farms. The offshore wind farms will be located in the Dogger Bank Zone which is located around 71 NM off the east coast of England (MarEx, 2015). This puts huge challenges in all phases related to construction and operations of wind farms offshore. The majority of wind farms available today are concentrated to the 20x20 zone (20 CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 9 km from shore and in 20 meters depth). Most of the future offshore wind farms will become bigger in terms of capacity and going into deeper waters, in some cases go further out at sea as seen in figure one (EWEA, 2011). Figure 1 – Present status of online, consented and under construction offshore wind farms (EWEA, 2011) The analysis based upon EWEA’s information and present trends reveals that the major projects are still beneath 60 meters of depth; however they vary in relation to distance from shore. Still the majority is found in the 60x60 area, but there are fields that extend in distance in relation to the depth 60m. The ones that exceed 60 meters of depth, mainly related to deep offshore wind farms will most likely involve new concepts of wind turbines. These floating units are under development however in reaching a field deployment require further modifications and testing to overcome the operational constraints of the sea (EWEA, 2011). Academic Relevance The subject area is appropriate of an academic relevance as it addresses an area where research needs to be involved more in the process and development. It’s also an emerging industry were new design concepts and various technology solutions constantly is entering the market and changing the operational environment. The safety aspects in accessing a wind farm turbine are of outmost importance and need to be examined further in order to secure strategies in the development of access systems and evaluate procedures in relation to remote offshore wind farms. CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 10 Purpose The main purpose is to investigate how changing operational requirements affect operational limits for Crew Transfer Vessels in order to secure safe and efficient maintenance and support operations in remote offshore wind farms. Research questions The research questions have been formulated based upon two main areas, followed by two sub-questions: 1. What are the present operational limits in practise that affect the operating window for maintenance and support tasks for Crew Transfer Vessels? a. What type of procedures and access systems exists today in order to meet these limits? 2. How will remote offshore wind farms affect the operational limitations for the operation and maintenance phase? a. How can existing procedures and access system be developed in order to meet new operational requirements? Limitations This thesis does not focus on technical aspects, so various design of vessels and access system options have been left out, only short description of different concepts are published. The focus on the thesis is not to add any comments or judgements on different matters on design in order to have a more objective view on the subjects. Further on, the thesis focus only on the O&M phase. Structure This structure is based on traditionally academic approach and layout. It starts with an introduction to the topic and followed by theory description. After that comes the method description, followed by findings chapters and a discussion chapter, which make out the body of the whole dissertation. In the end there is a conclusion chapter. CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 11 2 THEORETICAL OVERVIEW Offshore wind farms The primary components of an offshore wind farm include several turbines placed in a special designated area and these are connected by a series of cables to an offshore transformer or substation station. This one is further on connected to an onshore transformer station before the electricity finally enters the grid. The wind turbines are often placed latterly and divided to minimize the wake effects and turbulence. Placing the turbines closer to each other also reduces the amount of cables put down in the water. The position of each turbine must be planned in detail in order to maximize the power generation for an effective cost per unit optimizing (Malhotra, 2011). In Europe the wind farms are growing in terms of total project capacity and this development has affected the size of individual turbines. In 2011 the average size of an offshore wind project was 199 MV and already by 2012 this number has grown with 36 % to 271 MW. Looking upon the future planned projects, the average size could be over 500 MW (EWEA, 2013). The new Dogger Bank project “Dogger Bank Creyke Beck” that was announced in early 2015 has a total generating capacity of 2.4 GW through two different wind farms containing around 400 turbines, demonstrates the potential of far offshore wind farms (MarEx, 2015) 2.1.1 Wind farm Turbines The wind turbines offshore have gone through several design considerations; these have to meet more loads and environmental conditions than those onshore. Sea waves, currents, ice impacts from CTV’s and even wild life have to be considered while designing the turbines and could have a great effect on the turbine foundations. A wind turbine consists of many complex components some located above the waterline and some below and the most common used today are monopiles. In the development of new fields further offshore and as technology for wind turbines improves, the industry needs stronger and bigger wind turbines to optimize the cost benefits. Turbines that have a 150 m of rotor diameter with the capacity of 7, 5 – 10 MW could be a reality in the future which creates new operational challenges as some of these might be floating units (Malhotra, 2011). 2.1.2 Different phases for offshore wind projects An offshore wind project go through different phases during its lifetime and selection of the site requires a great amount of consideration. The obvious consideration is the area where the greatest amount of wind is located however some other important aspects are:  Distance from shore  Proximity to electrical grids, companies and the undersea cables  Visibility  Disturbance of any routes for airplanes and ships  Bird migration flight paths (Nicole, 2013) CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 12 When these factors have been considered the design, construction and installation of the wind farm can begin. When the installation process have been completed and the wind farm has been connected to the grid ashore, the commissioning can be complete as a final verification of functionality and operability. After the commissioning of the wind farm, it’s ready to produce electricity during the operation and maintenance (O&M) phase of the turbines and the farm (Nicole, 2013). 2.1.2.1 Operation and Maintenance (O&M) of an offshore wind farm This phase relates to two main activities as implied by the name: Operation – this refers to mainly management and “operations” of the farm or project and includes such as remote monitoring, environmental monitoring, electricity sales, marketing and other office tasks. Operations involve only a small proportion of O&M costs. Maintenance – these activities stand for the largest part of total O&M effort and cost. This part refers to inspection, maintenance and repair of the physical plant and is divided into two main areas:  Preventive maintenance – involves scheduled or proactive repair to, or replacement of known wear components based upon routine inspections or by information from different condition monitoring systems. Activities such as routine surveys and inspections are included.  Corrective maintenance – involves reactive or unscheduled repairs or replacement of failed or damage components. This may also affect serial-defects or problems that affect several wind turbines at one site. (GL Garrad Hassan, 2013) 2.1.3 Accessibility and availability The issue of accessibility is determined by the percentage of how much that turbine can be accessed, this is a major factor that will affect the operation of an offshore wind farm (Salzman et al, 2009). Access difficulties can be highlighted in the effect of device availability; availability is defined by the amount of time the turbine is operational to create electricity (Faulstich et el, 2009). Availability is therefore dependent on a number of factors such as failure rates, downtimes for recovery after failure, non-accessibility, lack of spare parts and logistical problems, which will have affection on availability. The accessibility in the offshore wind farms is especially critical due to loss of production from an OWT (Offshore Wind Turbine) which is often the greatest cost penalty for the wind farm operator (EWEA, 2009). According to Van Bussel (2002) “for a 150 unit wind farm consisting of 2 MW wind turbines at least 600 visits have to be paid each year to keep it in full operation”. Van Bussel also highlights local conditions as predominate factors that affect accessibility but this is also dependent upon the way which the turbine is accessed. For example, the large offshore wind farm in the North Sea at Horns Rev, the availability is around 90 % with accessibility by vessel on 65 % (Van Bussel, 2002). With reference to year 2013 the average availability rate was between 90-95% for a typical offshore wind farm (GL Garrad Hassan, 2013). This can be compared with an onshore wind farm with availability on 95-99 % (Dai, 2014). CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 13 In order to ensure a high availability for offshore wind farms, fast on repairs or device recovery must be done, that require that the level of accessibility needs to be quantified in order to ensure good economics (O’Connor, 2012). A majority of all the maintenance on an offshore wind turbine requires transfer of personnel and of parts hoisted up by the turbine’s internal crane, according to Rademaker & Braam (2002) this transportation and access can be done in (Hs) up to 2.0 meters. However, according to Salzman (2007), even if the vessels are being built stating workability up to Hs 2.0 m, the operators claim a more adjusted level between 1,5-2,0 m Hs. In the study from Van Bussel & Bierbooms (2003) looking upon different methods of transportation during the O&M phase for a wind farm located 45 km (24NM) off the Dutch coast. The study established the following table 1, were different level of accessibility was estimated from different wave height limits. Table 1 –Illustration of level off accessibility (compiled from Van Bussel & Bierbooms, 2003) Wave height limit Hs(m) Accessibility (%) 0,75 34 1,5 71 2 84 3 95 The study reveals accessibility on 71% on wave heights around 1.5 m Hs and 84 % accessibility on Hs 2.0 meters. These numbers were almost confirmed by Salzman (2007) who did a similar study looking upon yearly distributions for two different fictitious wind farms; one located 37km (20NM) offshore and one located 100km (54NM). Table 2 demonstrates the values of accessibility for the two farms. Table 2 – Different level of accessibility for two different farms (compiled from Salzman, 2007) Distance to shore Year-around accessibility % Hs= 1,0m Hs=1,5m Hs 2,0m Hs=2,5m Hs=3,0m 37 km 45 68 83 91 95 100 km 36 60 76 87 93 The study indicates that if the access system (vessel and transfer method) can work up to 2.5 m Hs it can be used for around 90 % of the year for both farms. 2.1.3.1 Accessibility and economy In order for the industry to be competitive and cost efficient in the future the level of availability needs to remain high. Therefore it’s important to identify a relevant level of accessibility to an offshore wind farm, the costs and incurred revenue losses for downtimes due to none-accessibility are strong incitements to develop access technology (Dahlén & Jakobsson, 2009). In order to found ambitious large-scale offshore wind projects it’s important to reduce the risks for possible investors. The wind turbine availability is the main factor influencing as it determines the obtainable income factor directly (Scheu et al, 2012). CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 14 Demonstrated in figure two illustrates indicative trends of cost of O&M in relation to availability. Figure 2 – Costs connected to different levels of availability (GL Garrad Hassan, 2013) Even if the cost of lost income declines zero as the turbines approach 100 % availability, the total cost in achieving that will increase dramatically. As the wind turbines is planned to become larger in the future, the risk of increased losses per unit time is an important aspect that affects tractability for further investment in the offshore wind sector. When the wind farms intend to move further out as sea, projects intended to become more complex, therefore, an optimal availability and cost effectiveness will require better accessibility (Dahlén & Jakobsson, 2009). It’s important in O&M strategies to have an overview over the costs associated with the operations of the wind farm, it’s also important to work with good models in order to plan for maintenance and inspections in order to reduce costs (Rademakers et al, 2008). Operation and maintenance costs are expected to stand for around 15 – 30 % of the cost of energy generated by offshore wind, maintenance and support strategies are vital to control these costs (Fischer et al, 2013). As a significant contributor to the total cost of energy, finding or exploring different concepts to reduce the cost of O&M services and optimizing asset performance have important role in the future (GL Garrad Hassan, 2013). O&M strategies for offshore wind farms The main activity for offshore logistics is to cover the duties related to operation and maintenance (O&M), mostly focusing on transporting technicians and their equipment out to the different wind farms for their different duties. Each offshore wind project has different characteristics, which determine the optimal strategy for operating and maintaining the plant, the main factors are:  Distance from onshore facilities  Average sea state  Number, size and reliability of turbines  Offshore substation design (GL Garrad Hassan, 2013) The most influential factor affecting, is the distance from onshore facilities to the offshore wind farm, this factor has the largest impact on the cost associated with O&M for wind offshore projects. For this reason, the distance from shore is also the primary consideration when determining the most cost-effective approach to O&M. There are three factors to consider regarding vessel concepts for O&M duties: CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 15  The weather conditions, more focusing on wave heights, wind speed and currents, affecting the operability of the vessel, personnel safety and accessibility of offshore structures.  The distance between the port and the working area, this together with a particular vessel’s transit speed decides the required journey time and therefore the actual working time on site.  The water depth in the working area, however this has more affection on jack-up rigs, which have a limitation on working depth. (Bard & Thalemann, 2011) A study by the ship design consultancy BMT Nigel Gee assumes 15 person-days of planned maintenance per year for a standard 5 MW wind turbine (Bonafoux, 2011) another suggestion is 40h of planned maintenance per year for a wind turbine (Zander, 2009 The transport consultancy UNICONSULT suggests the following data (Bard & Thalemann, 2011):  A team of 5 technicians will probably be needed for conducting a service job on one wind turbine at the time, two will probably be seasick during the journey out, and by that unfit to enter the wind turbine. The 3 technicians that remain can conduct the work.  The Manufactures calculate with 6-7 technical malfunctions per turbine and year, these can be handled in one day of work or less.  100 % of the wind turbines undergo an inspection once a year. During the inspections much of the components are verified carefully and malfunctioning items are replaced. This will take 2-3 days per turbine.  100% of the foundations and 50 % of the cabling undergo planned inspection of 1 day once a year. A consulting firm for the renewable energies PROJECT53°, stated in May 2010, that the upcoming offshore wind parks in the North Sea and the Baltic Sea are planned to contain around 80 or more wind turbines and possible distances will be more than 60 NM, this will have affection on vessel strategies and capacity. The options in reducing this transportation will have impact on site availability, therefore the choice of vessel fleet composition and the investment in potential offshore platforms will have great impact on O&M costs (Halvorsen-Weare et al, 2013). In the study by Besnard et al (2013) A model for the Optimization of the Maintenance Support Organization for Offshore Wind Farms, modelled different support organization and cost- based optimization in relation to location of maintenance accommodation, the numbers of technicians, the choice of transfer vessels and the choice for helicopters. The model was based upon a generic wind farm of 100 turbines of 5 MW each and located 60km (32NM) offshore. The most cost efficient solution was to use an offshore accommodation on service 24h / 7 days a week, and a crew transfer vessel with a motion compensated transfers system (Fisher et al, 2013). Utne (2010) identifies some important aspects in her study Maintenance Strategies for deep- sea offshore wind turbines, that the needs for maintenance and maintainability are used as a base for analysing and modelling optimization of planning and execution of maintenance actions. These are verified with operational experience and through tests, a maintenance strategy can be established for a certain deep offshore wind farm, further cost reduction can be achieved and availability maintained. CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 16 Even with an almost perfect wind turbine, considering design, components simplification and reliability of components, maintenance will always be necessary (Utne, 2010). Developing new concepts of deep-sea offshore wind farms/turbines and at the same time trying to reduce operations and maintenance costs is a complex process involving many different people with different knowledge. Due to the fact that design of the different parts in a wind turbine are carried out in different work groups compared to those working on maintenance and support activities creates a transfer gap. This separation imposes challenges with the need to share information and exchange of knowledge. It’s therefore hard to assess how different design solution affects maintenances and support tasks (Utne, 2010). In another study carried out by Scheu et al (2012) Strategies for large offshore wind farms; the focus was to evaluate how different variations in maintenance fleets can be optimized dependent on different weather forecasts and with the respect of site availability, cost savings and deployment of equipment. For the study a hypothetical wind farm where selected with a capacity of 2.5 GW close to the UK east coast consisting of 500 turbines, each with a capacity of 5MW. With regards to fleet variation four different combination of fleet sizes were considered, the alternative with the largest fleet (3 vessels with 3 cranes) had the highest availability achieved with slightly above 90 % (Scheu et al, 2012). The study focused on wave height boundaries from 1 – 2,6 m. At the limit of 1,4 and above an increased numbers of ships increased the availability and the alternative, with one ship and one crane ship only, secured a availability of slightly above 80 %. In the weather forecast scenario the number of deployments were observed in relation to “look ahead time (48h)” from weather forecast (predicted weather). In this scenario the same type of vessels were used. The Crane vessels have a stronger amount of number of deployments compared to the ordinary ship, the reasons were shorter transit and repair times and the ability to stay longer at the field compared to the ship that has to return to port for new loadings (Scheu et al, 2012 A 5 MW turbine was used as reference with all different fleet combinations and the highest boundaries have been evaluated for the diagram, a strong linear correlation exists between availability and production losses. For example a change of wave height boundary from 1,0 to 1,8m for both access methods in a “one ship one crane ship” configuration, would decrease losses with 30 %. The study also concludes that a cost savings can be achieved with better and more advanced access systems. Different Access systems In the literature access systems are sometimes used as a phrase for transportation vehicles (i.e. vessels and helicopters). The access systems used today differ in design, concepts and with procedures ranging from boat-ladder landings (CTV’s), lowering from helicopters, temporary gangways lowered from larger vessels. This also involves complex platforms developed by other industries (Dai, 2014). Environmental conditions like wind, sea state, current etc. have huge impacts on the operations of different access systems; vessels are limited mainly by wave heights and currents and helicopters by high wind forces and visibility. The task of finding a suitable access system is complicated with regards to technical implication and the cost for purchasing (Dai, 2014). Seen below in table 3 are different characteristics of different access methods CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 17 presented with their operating limits, advantages and disadvantages. Different types have different capabilities and all has to be evaluated depending maintenance strategies, travel distances and field characteristics. Table 3 – Different access systems (compiled from Knudsen C et al, 2011) 2.3.1 Helicopters This is an additional service that can be used together or separate from the workboat solution, helicopters have short transit time and can operate without regards to sea conditions and by that better accessibility. However the cost associated with helicopters is much higher and another disadvantage is that they only can carry a few technicians and a limited amount of equipment (GL Garrad Hassan, 2013). Despite that there are operators today that are embracing helicopters in the mean that they can cover a larger number of sites faster than work boats, then making it more cost efficient. There are still some uncertainties over how widespread their use can be, mainly restricted to their safety and regulatory implications which have not fully been explored (GL Garrad Hassan, 2013). 2.3.2 Accommodation ships or fixed platforms offshore Accommodation ships offshore also called SOV (Service Offshore Vessel) or “mother ships” and fixed platforms is a new strategy which will have an increasing influence when the wind farms are moving further out at sea (MacAskill & Mitchell, 2013). Today “hotel ships” and different types of fixed platforms are used to some extent within the industry for the technicians to remain offshore without going back and forth from the shore base with CTV’s. The main purpose of these is to host technicians, spare parts and repair facilities for a longer time offshore, allowing O&M tasks to be more efficiently conducted and avoiding longer transfer time. Type Significant wave heights in metres Average wind speed in m/s (1hr at 10 m height) Example of application Advantages Disadvantages Direct boat landing 0,5 - 1,5 (rubber boats) 2,5 (SWATH) 10 Nysted (rubber boats) Bard 1 (SWATH) Simple Sensit ive to marine growth and icing Boat landing with motion compensation 2 - 2,5 (OAS) 2 - 3 (Ampelmann) 11,5 (OAS) 14 (Ampelmann) Tested Not sensit ive to marine growth Installation of addit ional equipment on the vessel required Crane hoist 2,5 ? None Not sensit ive to marine growth Remote control of crane, Maintenance offshore required Helicopter None 15 - 20 Hors Rev, Alpha Ventus Not sensit ive to waves, fast transport Expensive CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 18 Figure 3 –Ulstein SX175 with X-Stern; SOV Concept for offshore windfarm (photograph courtesy of Ulstein, 2015) In figure three, a SOV design concept from Ulstein (SX175) with X-stern is demonstrated. This type of vessel can in addition to the gangway capability use small workboats stored on- board for launch and recovery in acceptable weather conditions. In rougher conditions the technicians can access the turbines with special heave compensated gangways maintaining a higher operational window (MacAskill & Mitchell, 2013). In the proposed Dogger Bank project in the North Sea, where the wind farm site has a planned capacity of 9 GW and will most likely become the world’s largest wind farm, located between 125 km to 290 km offshore require new methods for performing O&M duties (Gundegjerde & Halvorsen, 2012). Due to the location and the exposed area several concepts are analysed and there is a need for the accommodation unit to stay on site for a more effective operation. Helicopters are also a solution that can be available on these ships (Gundegjerde & Halvorsen). 2.3.3 Direct transfer In direct transfer special designed work boats or CTV’s transport technicians to and from the wind farm. These are operating from a port base in close vicinity of the wind farm. The direct transfer is most suitable in scheduled and planned O&M activities but response time and accessibility are often limited by transit time and environmental factors (GL Gerrad Hassan, 2013). It’s the most common method used today but the main limitations come from wave heights and currents, especially wave heights. As the vessels start to move up and down the turbine friction bars, when the conditions become too rough and unsafe for the technicians access the turbine. Direct transfer can be done with normal mono hull vessels but usually special designed vessels are used. These are less sensitive to waves due to their shape of the hull. The most common used today are catamarans and SWATH (Small Waterplane and Twin Hull). Due to the twin hull design they are more stable in waves and can work in higher sea heights. See SWATH type in table 3 for wave height limitations (Knudsen C et al, 2011). Mostly fenders are used on the vessel to create friction and prevention of damage on the turbine when this type of transfer is used (Knudsen C et al, 2011). CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 19 2.3.3.1 Vessel Concepts – Crew Transfer Vessels For the majority of the tasks during the O&M phase small supply vessels, or Crew Transfer Vessels (CTV’s are used. Normally these can carry 12 passengers and have a load capacity from 1-2.5 tonnes and can proceed in speeds up to 30kn. RIB’s (Rigid Inflatable Boats) are also used but only for shorter distances and in good weather conditions. For carrying more heavy equipment like main bearings or a yaw drive a larger supply vessel is required or a so- called Multi-purpose vessel (MPVs), often this is needed when lifting capacity is required (Gundegjerde & Halvorsen, 2012). In the early stages of wind farm operations local chartered conventional vessels were used as CTV’s. However this has changed due to new operational requirements, adoption of new design technology and to increase the comfort for the technicians. An example of that is the SWATH’s CTV’s, the SWATH technology or design is minimizing the ship's volume near the surface area of the sea. It’s in this area the wave energy is located and that maximizes the vessel's stability, even in high seas and at high speed. Therefore it makes SWATH’s ideal in order to increase comfort for the technicians. The different vessel concepts that are available today have mainly been constructed after different kinds of national standards or codes, which can vary from country to country. This adds a dilemma when operators want to employ their vessels in different jurisdiction around in Europe, causing problems with interpretation. Stakeholders and Flag states have asked for a more transparent and uniformed set of regulations and design standards in this segment in order to have a standardize approach to vessel capabilities (Bard & Thalemann, 2011). For example the classification society DNV has published specifications for wind farm service vessels in January 2011 based upon the High Speed Craft (HSC) Code developed by the International Maritime Organization (IMO). This has been revised and the latest version is from July 2013 (DNV GL, 2013), Service on wind farms and other offshore installations. It addresses not only design criteria’s. It also includes requirements regarding personnel transfer system, cargo and fuel transfer system and noise and vibrations. . The specified CTV classes comprise:  “Windfarm Service 1”-vessels: length < 24 m, transport capacity of 12 technicians  “Windfarm Service 2”-vessels: length >= 24 m, transport capacity of 13 to 60 technicians (Bard & Thalemann, 2011) The crucial aspect for these vessels is the transfer time, which can limit the working time on site, for example slower vessels are not suitable for far offshore working areas (Bard & Thalemann, 2011). Figure 4 shows speed curves of monohull-, catamaran- and SWATH vessels in relation to transfer time limits given by the wind farm operators. It demonstrates an acceptable transfer time of 60 minutes and 80 minutes as maximum. Further assumptions are based upon average sailing speed of 17 kn for SWATH CTV’s, 21 kn for catamaran CTV’s, and 30 kn for fast monohull CTV’s (Bard & Thalemann, 2011) CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 20 Figure 4– Vessel transfer times and reference times over distance to port (Bard & Thalemann, 2011) The maximum transfer time limits create a maximum transfer distance of 23 NM for SWATH CTVs, 28 NM for catamaran CTVs and 40 NM for monohull CTVs. A proposed wind farm wind working area of 60 NM offshore no CTV could arrive at site on time (Bard & Thalemann, 2011). In assuming a daily work time of 8-12 hours and transfer time of 2-3 hours (20-30 knots at a distance of 60 NM offshore) the PROJECT53° calculates with a shore assisted maintenance concept, this will only allow an effective working time of 4-6 hours. (Bard & Thalemann, 2011)This may be insufficient for some maintenance operations and could also affect operational safety due to the time pressure. The solution may be to add higher sailing speeds but with the limiting factor of sea heights a restricted weather window will only be achieved and this not an attractable solution (Bard & Thalemann, 2011). Another solution is to add a mother ship concepts in these circumstances with the capability of deploying on-board stored CTVs. This could reduce the transfer time significantly to perhaps less than 0,5h and 6-10 h effective working time on site may be achieved (Bard & Thalemann, 2011). 2.3.4 Access methods options In addition to several different designed boats or vessels, other access options have been developed in an ambition to actively or passively compensate for movements of the waves. These types of active or passive gangways and bridges are usually mounted in the front of the CTV or on the side of a larger vessel allowing the technicians to “walk to work”. Practice within the industry has been to butt the CTV tightly against the friction bars on the tower and hold it with forward propulsion. This “bump to bump” method works for smaller vessels and lighter conditions with wave height to around and less of 1, 5 m Hs (Marsh, 2013). However as the wind farms move further out at sea and with an ambition of higher accessibility, then a larger operating window in waves up to 2,5m Hs or even more is needed. This creates a demand for new methods of transferring technicians safely to OWTs. CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 21 The challenge is to control the 6 degrees of freedom (pitch, roll, heave, surge, sway and yaw) which is the reaction pattern for a vessel that moves freely in the sea as seen in figure 5. Figure 5 - “6 degrees of freedom”, image used with permission (2015) Depending on which vessel that is in focus, different strategies exist how to control or monitor the degrees of freedom. A CTV could stabilize all motions while pushing on for example. Within this lies a technical challenge and there exists a trade-off between cost and performance. Below are examples of different solutions that exist both actively and passively. The primary objective is to stabilize all motions for the access point in order to achieve a safe access condition. There are two schools of thought of what approach is the best:  Active positioning – uses a heave compensated gangway that are linked to a motion reference sensor. Signals of bow motions are then reversed in the access system and the access system actively compensate for the bow motions. For example if the bow raises the access system falls. With this solution the vessel does not need to be connected to the turbine, it can be positioned 10-15m off or more from the turbine with a dynamic positioning (DP) system.  Passive positioning – Relative motion between the vessel and the turbine tower is accommodated by a mechanical linkage which adjusts itself passively, the main difference compared to an active system. This is done with no servos or control system (Marsh, 2013). Operational procedures of crew transfer 2.4.1 Normal conditions A normal condition intends to describe periods when the projects operate as planned and when sea and wind conditions are on an acceptable level for safe transport and access to turbines. Preferred normal maintenance and inspections are conducted during these periods and interruptions based upon environmental factors are low. This period may last for 65 to 80 % a year depending on area (Dahlén & Jakobsson, 2009). 2.4.2 Extreme conditions In extreme conditions a safe access to turbines becomes more difficult and even impossible. Access systems may allow boarding and disembarking in levels of 1,5m Hs, however the first and foremost conditions is for systems to function in high amplitude waves but the length of the seas can vary dramatically and affect accessibility with regards to wave heights (Dahlén & Jakobsson, 2009). In some areas like the Baltic Sea and even some shallow parts of the North Sea, the waves may be short and difficult (Choppy Sea) despite lower wave heights. Shorter wave lengths makes conditions more difficult than larger. CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 22 At some operational sites there exists a strong current. With the combination of strong winds affecting wave heights, could be even more challenging conditions due to the diversity of forces acting upon the access direction and creates difficult docking situations (Dahlén & Jakobsson, 2009). Even tidal conditions can affect access systems. This requires completely different requirements and needs different types of systems in order to be able to adjust for change in sea levels. Wind farms are not common in icy areas, however there are those how can be exposed to cold environments affecting ladders near the splash zones with ice build-up, hampering accessibility (Dahlén & Jakobsson, 2009). 2.4.3 Industry procedures and guidelines Within the industry today different types of “best practice” guidelines or procedures exist that address crew transfer from different perspectives. These have been introduced in an ambition to have a common approach for crew transfer. Described below are three different guidelines. 2.4.3.1 IMCA M202 IMCA (International Marine Contractors Association) address in its document M202 boat transfer for the offshore renewables industry, the guidance document also takes up issues that affects different types of transfers in general such as risk assessment, training, responsibility and communication. The documents states; -“Transfer of personnel in the offshore renewable industry follows similar principles to that in the traditional offshore construction or oil and gas industries but there are some differences” (IMCA, 2014) The procedures are quoted from M202:  The majority of personnel transfers are made using small vessels of 10m to 30m in length using a ‘surfer’ arrangement (see section 4.5.1.1);  Crew transfer vessels (CTVs) in the offshore renewable energy industry are generally of displacement less than 500 tonnes and those mating with surfers are normally limited to 100 tonnes due to impact forces on the boat landings. Most boat landings are limited to a static impact force of between 200 and 240 kN and an emergency dynamic impact of 1,000 kN though the specifics for each structure will need to be determined at the time;  Personnel are primarily transferred from a base port ashore or accommodation offshore to the foundation structure of the wind turbine or other renewable energy generator and return at the end of the day;  Depending on the capability of the C T V , transfers are generally limited to 12 passengers, with only a few vessels certified to carry over 12;  The potential wave height in which transfer can take place can vary from location to location. In all cases, it should be demonstrated that the risks identified in section 3.1 have been appropriately assessed and mitigated. The maximum wave height at which transfer is allowable may be increased through use of transfer access systems such as dynamic gangways or active fenders;  CTVs may also carry cargo which can be handled on the forward or after decks using the cranes mounted on the renewable energy structure or installation/support vessels;  Landing areas for personnel transfer by carrier are often small or limited which can impact safe transfer;  Personnel being transferred should be using the appropriate PPE as described in section 3. Additionally, personnel should have received appropriate training in CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 23 climbing and, according to the on-location risk assessment, be wearing immersion suits that are suitable for climbing. (IMCA M202, 2014) The document also addresses risk assessment as a tool, irrespective of transfer method and should be carried out beforehand, the risk assessment could be completed as a part of the daily safety briefing or toolbox talk (IMCA, 2014). The assessment should address issues such as environmental conditions, vessel motions (Pitch, Roll and Heave), seaworthiness, training of involved personnel and a lot more (IMCA, 2014) 2.4.3.2 Good practice guideline – G9 The G9 Offshore Wind Health and Safety Association (G9) consists of nine of the world’s largest offshore wind developers, who have jointly come together to focus on important issues related to health and safety within offshore wind industry. This document “The Safe management of small service vessels used in the offshore wind industry” is produced as a part of that work and was published in November 2014. It addresses issues such as site management, marine coordination, marine operations, vessel management and it also contains some annexes. In chapter 4 marine operations are addressed and particularly passenger transfer to wind farm structures. In chapter 4.2.2 the following is extracted: ..The Transfer Assistant should: - conduct visual inspections of the ladder, transfer area, boat and structure fendering; - conduct pre-use checks of the Self-Retracting Lifeline (SRL); - conduct pre-use checks of any personnel transfer system in use, and - notify the Master on satisfactory completion of the checks. The Master should authorise personnel transfer based on: - the motions of the service vessel; - the prevailing environmental conditions, and - the stability of the connection between the vessel and the structure. Vessel motion monitoring systems may be fitted to assist the Master in judging the appropriate conditions for a safer transfer. Once the Master has authorised transfer from the vessel, the Transfer Assistant should: − call the first transferee forward to the transfer area; − check correct use of PPE by the transferee; − pull down the SRL and assist the transferee in attaching it; − stand back from the transfer area and observe the transfer when the transferee is clear of the vessel and − notify the transferee and the Master of any potential hazards observed during the transfer. When recovering passengers to the vessel, the Transfer Assistant should: - count down the remaining rungs of the ladder to the transferee and inform the transferee when it is safe to step across to the vessel; - assist the transferee back onto the service vessel, and - assist with disconnection from the SRL (Energy Institute G9, 2014) CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 24 Limiting weather criteria The Guidelines also address weather criteria and it lies with the responsibility of site management to establish limiting weather criteria for all marine operations that are to be under taken in the windfarm, these should include but not be limited to: − Significant and maximum wave heights − Wind speed and directions − Peak speeds and direction − Peak and mean wave periods − Current strengths and directions and tidal ranges The vessel specific limiting criteria should involve the service vessel and its motions in different weather conditions and be referred to the operating limits defined by the vessel operator or class documentation. Concerning any marine operation, the limiting criteria should be defined covering the whole operation and the master, marine crew, passengers and marine coordination should understand and have knowledge about these values. In addition to limiting criteria site management should also define marginal criteria for all operations undertaken in the wind farm. As reference the marginal conditions should be less than the limiting. The responsible marine coordinators should monitor current and weather forecasts and inform any service vessel involved in a concerned wind farm if the criteria of the forecast are to be exceeded during the operation (Energy institute G9, 2014). 2.4.3.3 The Renewable UK The Renewable UK address in its publication Vessel Safety Guide Guidance for Offshore Renewable Energy Developers (2012) the issues with Sea states and Weather forecasts as essential in order to carry out activities in a safe manner and states the following:  The weather limitations of the activity need to be determined taking into account the site and duration of the work;  The selected vessel must be capable of operations within the expected prevalent conditions with a safety margin to allow for changes in environmental conditions;  The assessment of weather conditions should include the time to transit to/ from the site and distance from a safe haven;  A common understanding of the limitations of the vessel between all parties is essential;  Site specific and up to date weather forecasts need to be reviewed to allow planning of the operation;  Local weather, wind, tide and sea state characteristics and other applicable metocean data must be taken into account at the time of carrying out the activity;  Local conditions should dictate when operations are safe to continue;  The environmental conditions should be below the limits set within the risk assessment and procedures for the activity. (Renewable UK, 2012) In the document Offshore Wind and Marine Energy Health and Safety Guidelines (2013) Access and egress procedures are highlighted. The standpoint is that every transfer exposes the people involved to a number of significant hazards. With regards to expected frequency of transfers, extremely robust and repeatable systems are required in order to ensure that the overall risk remains at a tolerable level and states the following (Renewable UK, 2013) The following part has been retrieved from chapter C in that document. CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 25 C.1.2.5 MANAGING THE RISKS A wide range of factors that could affect the risk to people transferring from vessels needs to be considered:  Any access system needs to have a clearly-defined operating window, supported by robust evidence of capability relative to metocean condition limits such as: o Wind speed and direction; o Sea state - wave height (significant and maximum), direction and period (which combines with height to affect steepness); o Visibility � fog, hours of darkness; o Effect of tidal height and currents; o Sea temperature; o Air temperature, as very cold conditions, combined with rain or sea spray, can cause icing on ladders and fall arrest systems; o Uncertainty in measurements or variations across a site;  Site characteristics, such as the distance to the onshore base or safe haven, will affect routine and emergency planning arrangements;  Structure to be accessed: o Orientation of access point(s) relative to prevailing metocean conditions; o Design of interface: o Structural strength; o Compatibility with vessels, including maintaining a safety zone so that the person on the ladder cannot be injured by vessel movement relative to the ladder; o Condition of the interface at the time of transfer, such as damage / deterioration, and contamination; o Guano presents a range of health risks, including the potential to aggravate respiratory disorders such as asthma; Relative movement of floating OREIs, or accommodation vessels, against access vessels, in response to the sea;  Access vessel: o Capability relative to metocean conditions; o Skill and experience of crew(s); o The manner in which it interacts with the landing system, for example, whether it moves under a stick-slip friction regime, or gradual release;  Human factors: o Pressure (from any source, including oneself) to get the job done: o Frustration if unable to transfer after long journey to site; o Wanting to get off vessel after journey in rough conditions; o Not wanting to be stranded, even if conditions have deteriorated whileon the offshore structure; o Financial incentives for offshore working; o Ability to make objective safety / capability assessments prior to a transfer, particularly if cold, wet or suffering from seasickness; o Fatigue, due to factors such as long working hours, intensive campaigns, or long transit journeys in rough sea. (Renewable UK, 2013) CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 26 Training and competence The training standards for the marine crew for CTVs are dependent on their size and passenger capacity. Normally these vessels are only certified to take maximum 12 passengers along. These requirements then formulate the competence level needed for the marine crew. The STCW (Standard of Training and certification and Watch keeping) addresses these issues on larger vessel normally above 500 GT. For the wind farm support vessels often different local or national rules apply like the British Large Commercial Yacht code (LY2) for masters on yachts up to 200 GT (MAIB, 2013). There has been a lack of a uniformed standard across the industry however the focus has changed and this ambition is address in several guidelines and IMCA are presently working on a competence standard for masters and deck crews. A key element of a master on a CTV is navigation, boat handling and manoeuvring close to turbines; often the master and his training are focused on these types of skills (MAIB 2013). In the accident report by the MAIB (2013) involving the vessels “Windcat 9” and “Island Panther” which collided on two different occasions with two different floating targets (the different accidents are covered in the same report) lack of competence standards and training is highlighted as a contributing factors, it states: “There is little relevant industry training available for masters and crews of PTVs” (PTV – Personnel Transfer Vessel), (MAIB 2013). It’s further on mentioned that one training provider offers an introductory half-day course which includes lectures and practical exercise in manoeuvring a PTV to dock with a turbine foundation. The reports also highlight a need for marine operational guidance to owners/managers and crews operating PTV’s. Another conclusion addresses the issue that often the masters are coming from the fishing industry and they are not used to operate high speed transfer vessels and it’s important to focus on correct and continuous training. There are challenges in the development in identifying and agreeing upon relevant training standards throughout the industry, and should be considered to be an industry good-practice framework for stakeholders to work towards. These are not mandatory industry standards but to be seen as guidelines. (Renewable UK, 2014). HSE – (Health, Safety and Environment) Safety is defined as the freedom from those conditions than can cause death, injury and occupational illness, or damage to or loss of equipment or property (Standard Practice for System Safety, 2000). Most of the time the offshore wind farm is unmanned, therefore health and safety issues only concern the installation, maintenance and decommissioning processes (Dai, 2104). There are guidelines in place who address different aspects of the operations in place, despite that there has been seen a high number of incidents (see chapter below) associated with different operations such as; crane and lifting operation during installation, heavy maintenance work and access to and egress from OWTs (Dai, 2014). Many lessons can be drawn from similar industries such as offshore oil and gas which is much more mature with regards to HSE. The offshore oil and gas industry has a strong focus on avoiding collision between service vessels and offshore installations. In the offshore wind industry, as Sharples and Sharples (2010) indicate service vessels colliding with OWT’s are realized as a potential threat, but has not given much attention by designers and operators. CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 27 On the other hand several studies have addressed the issue of passing vessels engaged in other marine activity colliding with OWTs and the associated risks (Dai, 2014). 2.6.1 Incident Reporting Between January 2011 and September 2012 DNV GL conduced a review of the G9 incidents categorised under “Marine operations and “Personnel transfer” in an attempt to identify trends or specific high risk operations. Marine operations and personnel transfers in general were identified, as areas where significant risk applied, seen below is a table 4 of reported incidents: Table 4 – Reported incident activity (Compiled from the Energy Institute (G9), November 2014) Activity Category Comment Incident count % of total reports Crew or personnel transfer All incidents involving transfer of boat crew or other personnel. 27 16 General Incidents in which the specific activity is not important. The Hazard represents a general on-board condition or is related to general voyage. 24 14 Installation operations Installation of equipment at wind farm. 18 11 Deck activities Non-specific activities involving the presence of personnel on the deck. 14 8 Mooring Incidents taking place during mooring operations. 11 6 Maneuvering Incidents involving boat maneuvers within a wind farm or in the immediate vicinity of an asset (excluding personnel transfer) 8 5 Anchor operations Incidents during anchor operations. 6 4 Jacking-up Incidents during jacking-up 5 3 Housekeeping Reports involving failure to follow housekeeping procedures. 5 3 Jetting Incidents during jetting. 4 2 Deck cargo Incidents involving deck cargo. Usually failure to secure cargo. 4 2 Sum 126 74 Regarding the incidents crew and personnel transfer has the highest number involving 16% of the total reports of all the incidents where it was possible to determine an immediate causal factor, 46 % of these were linked to a failure to follow procedure. Further incident data have been collected for the year 2013 and was published in 2014. It again identified small craft vessels and crew transfer vessels in particular involved in significant number of reported marine operations incidents (Energy Institute (G9), 2014). In the report 616 incidents were reported, 131 of these occurred during marine operations and 281 of the 616 occurred on vessels. Figure 6 demonstrates incident regarding vessel breakdown and illustrates a high number of incidents for un-classed vessels, often these vessels are the CTV’s as these are not covered by class rules. CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 28 Figure 6 – Vessel incident break down (Energy Institute (G9), 2014) Regarding marine operation the below figure 7 illustrates different incidents related to that area. Figure 7– Marine operations – incident breakdown (Energy Institute (G9), 2014) Total incidents were 131 and 106 of these occurred on the vessel them self with the highest rating for unclassed vessels. The annual incident data report from 2014, reveals again marine operations as a high risk area, 228 incident occurred during these activities, the majority of these (159) occurred on the vessels them self. Those connected to “transfer by vessel” were 44% (Energy Institute (G9), 2015). Seen below in figure 8 demonstrates incident data breakdown and as for the year of 2013, vessels below 24 meters still have the highest number of incidents. CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 29 Figure 8 – Marine operations – incident area breakdown (Energy Institute (G9), 2015) CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 30 3 METHODOLOGY This thesis has a qualitative research approach and containing mixed methods as a mean to answer the research questions. Mixed methods The term “mixed methods” refers to research that combines alternative ways of data collection in a specific research project (Descombe, 1998). Two different methods have been used in this thesis; semi-structured interviews and a hierarchical task analysis (HTA) as a result of an on-board observation of a CTV operating in a wind farm. Mixed methodology gives the researcher the opportunity to verify the result from one method with the result from another and when different methods are providing the same result, the researcher may be able to argue for a higher level of validity. The data from different methods can also be used to complement each other and by combining different perspectives a more comprehensive result can be provided than an approach only involving one method (Denscombe, 1998). In addition, with insights of positive and negatives sides of both methods, the combination of two might compensate for weakness in one and possible critics arising due selection of only one can be met (Denscombe, 1998). Mixed methods can also be used to bring the analysis forward, where one method can provide information that can be used in another; in this case you use an alternative method to develop the information that has been produced by the first one. However using mixed methods doesn’t say that “everything is allowed”, there has to be a clear ground and motivation to use mixed methods, in the same way mixed methods are not applicable on all research areas Denscombe (1998). Grounded theory Grounded theory is an inductive and theory generation approach and does not test hypothesis as mainly normal research does (Denscombe, 1998). Grounded Theory is relevant when empiric fieldwork is required and when there exists a need to create theories from practical situations that exist in the reality. The primary objective is to develop the theories based upon high amount of data collected from the “field” or reality. The characteristics of grounded theory are to develop theories based upon the data in a constant process where the ideas always are verified against the existing data. The theories that arise should be improved through additional testing against data which is collected for this purpose (Denscombe, 1998). Data collection The data is collected from the two methods described below. 3.3.1 Interviews To provide a foundation for analysis of the research questions, semi-structured interviews were conducted. In addition semi-structured interviews were also conducted as a part of the on-board observation for better a standpoint in the analysis and verification of the procedures. The selection of informants is important with regards to purpose and research questions. For this method; shipping companies, wind farm operators and a classification society were selected as the most relevant stakeholders as they represent different perspectives: CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 31  Wind farm operators – They are responsible for the wind farm to produce electricity, and by that the operation and maintenance phase.  Shipping companies – They are responsible for the vessels, the management of these and operation.  Classification society – These organisations are responsible for vessel classification and approves vessel after construction. They are also responsible for classification of wind turbines and some of these does also provide operational guidance for marine activities. Concerning the classification society, two interviews were conducted as the first informant recommended an additional interview with a person that was more experienced and had further knowledge in these matters. Altogether six interviews were conducted and they lasted for 45-60 minutes each. The type of interview selected was semi-structured, as the importance was to get the informants to develop and share his/her depth knowledge and express more experiences in the subject. All informants were giving the same set of questions represented in Appendix A and received the questions in advance for better preparations, understanding of the contents and relevance of the interview. A face-to-face interview was conducted with three informants and due to different circumstances with large geographical separations, three interviews were conducted by telephone. The interviews were recorded and later on transcribed According to Kvale (1997) preparation is vital and the key questions is what, why and how; what – to get the relevant knowledge of the area before the interview; why – to have a purpose with the interview; and how – selection of the most suitable interview method. Therefore the interviews were organized according to Kvale’s (1997) “seven stages”: 1. Thematiation – This involves the formulation of the purpose of the research and a description of the content before the interview parts starts. 2. Planning – Planning and preparation of the seven stages in the investigation and how and when the interviews will be conducted. 3. Interview – To carry out the interviews. 4. Transcription – Preparation of the interview material for analysis which involves transcription of recorded material into text. 5. Analysis – Selection of analysis method in relevance to the purpose of the investigation and subject. 6. Verification – Establish the degree of validity and reliability 7. Reporting – To report the result of the investigation and the methods used. In addition Kvale addresses two main aspects in this; thematic and dynamic. Thematic - is the creation of interview questions in relation to the subject and the research question, the acquisition of knowledge. Dynamic – involves the ensemble between the interviewer and the informants. A good interview question should contribute thematically of knowledge production and dynamically with creation of human connection. Kvale highlights this relationship and ensemble for the best outcome, which where an important part of the interviews. 3.3.2 Hierarchical Task analysis (HTA) - On-board studies and observations CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 32 The second method used was a hierarchical task analysis (HTA) which was conducted on a CTV, participating in this type of operation, primarily transporting technicians and cargo to and from the wind farm. The observation was conducted on the bridge of the concerned vessel covering: navigation to field, different approaches to different turbines/floatels/substation and a cargo operation at a sub-station was also observed. The importance in this method according to Decombe (2009) is being part of the concerned environment and conditions and this enables a deeper understanding of specific activities in a defined task. In this observation the author’s identity was known to all participants on the vessel that day, technicians and the crew. This allowed the author to experience the operational environment, the tasks being performed and learn about the conditions, vital aspects according to Descombe (2009) for being able to analyse the observations with the right background. The data recorded was later on used for creation of the HTA. The stand point of the observer was mainly to be “out of the way” and when necessary record conversations and the operations that were vital for the observations. In using video- and audible recordings the vital parts of the observation was documented. 3.3.2.1 Conditions The on-board visit/observations took place on a CTV which was chartered for a recognized wind farm operator; performing its duties in a wind farm 50 NM outside the west coast of Denmark. On that day for the observation there were eleven technicians coming out for conducting different duties in the wind farm. The conditions were; easterly winds around 20- 25 knots, the wave height in the morning when arriving the field was Hs 1,5-1,7 m and maximum wave height around 2-3 meters slowly reducing. 3.3.3 HTA Hierarchical task analysis (HTA) is a method to describe tasks. The HTA identifies and characterizes the fundamental characteristics of a specific activity or a set of activities by observing what an operator or a group of operators need to do to achieve a given goal (Hollnagel, 2006). The method is widely spread and used in several different domains such as air traffic control, product design and nuclear domains as a few examples. The HTA is the natural step after a collection of data and provides a step-by-step description of the activity under analysis. The analysis breaks down the task into a nested hierarchy of goals, operations and plans. The advantages with using the HTA are, that it is a quick method to implement and requires minimal training and equipment to get a description of a complete task. With pen and paper one can easily perform an HTA. 3.3.3.1 Procedures The performing of an HTA according to Stanton, et al., (2006) are divided into six different steps that are described below: 1. Performing an HTA is to define the task that is being analysed. The purpose of the analysis should also be defined. In this report the HTA analysis CTV operation, all relevant tasks and subtasks performed by the crew, and as well identify tasks with higher complexity. CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 33 2. The data can be collected in many ways. For the HTA in this report the data collections were conducted with on-board observation, interviews and Video/Audio recordings. 3. Is determine the overall goal of the task. This determination is the top of the hierarchy in the analysis. In this report the overall goal of the task is to describe CTV operation. 4. The overall goal is divided into task sub goals, the sub goals together should form the tasks required to reach the overall goal. Sub goals in the HTA in this report is for example planning of the operation and execute a safe and efficient transfer to a wind turbine. 5. The sub-goals are divided into sub-goals themselves. This is done until it cannot be done anymore and the bottom level of the HTA is reached and the operation is fully described. 6. The planning of the analysis and should describe how the goals are reached. A simple plan would say do 1, then 2, then 3 and when it is completed return to the super-ordinate level. Example: for planning the operation perform these operations and then return to the next step that comes after the planning the operation. 3.3.3.2 Interviews as part of the HTA For better understanding in the analysis and for a better verification on the analysis made, interviews were conducted with two masters working on a CTV. Another set of question were used as seen in Appendix B compared to those used on the other informants. The interviews were semi-structured, as this allows the master(s) to be more explorative in the answers in sharing their experience and knowledge in this subject and providing further insights that was usable when making the task analysis. 3.3.3.3 Review The Analysis has been reviewed by two captains; the on-board captain and one from another similar company and the comments have been used as update on the HTA. Only small adjustment was needed due to this and no change of the colour coding was requested. Ethics All informants in the interviews were asked if they accepted that the interview was recorded and that they could stop the recordings anytime if they felt uncomfortable with the situation. Their identity is kept confidential with regards to statements in the result sections, and there categorized as informants A, B, C, D, E and F. In the observations a “Participant Consent Form” (Appendix C) was used for the marine crew to get their approval for the recordings, the technicians were also informed about the observation. Data Analysis The data analysis has been conducted using two steps, first each of the primary data collection methods. 3.5.1 Interviews To analyze that amount of data from the interviews a categorization or concentration of different contents in the interview is required. The main approach in this analysis was to use “sentence concentration” to reduce the amount of text. According to Kvale (1997) the transcribed text are concentrated to smaller statements where the most important contents are mentioned by a few words. CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 34 The analysis has used five steps defined by Kvale (1997) as an approach to formalize the contents of the interview to a result: 1. Reading of the whole interview was conducted, to be able to have an understanding of the totality. 2. The different sentences were contextualized as expressed by the informants. 3. This step involved the formulation of the different themes as simple as possible; the standpoint here was to interpret the expressions in the interviews with no subjective judgment and organize them into defined themes. 4. This step compares the different themes against the research questions and organize them dependent on the content. 5. The final step is to contextualize all themes relevant to the research questions in a formative text description. 3.5.2 HTA In the HTA, the complexity of the single operations was of relevance. To denote the complexity of a single task a colour coding of the HTA-tree cells was chosen. The colour represents how complex the task in the box is to perform. Since the HTA is an analysis of a standard operation with no errors, the colour also shows tasks that can go wrong and that might lead to complete other tasks needing to be performed. In that case it can also be demanding and increase the workload demands on the crew. The level of complexity was created by author upon his own assumption and previous experience working with offshore activities but with other types of vessel in demanding operations. The following colour coding has been chosen:  Black framed tasks represent tasks with low complexity , none-demanding; like planning and preparation.  The yellow framed tasks demonstrate that the crew has to pay attention. It can be when the captain is communication with other vessels or technicians in the wind farm or navigating to the field or infield between the turbines.  The orange framed tasks represent tasks with a higher mental workload which require larger concentration. Typical tasks marked orange are where the bridge coordinates the operation with the deck crew or the technicians, and the same time as the bridge, captain has to keep the vessel in position and perform other tasks, or navigating in high traffic areas or in reduced visibility.  The red framed tasks with the highest workload and focus. During these tasks the crew has to be very observant on what they all are doing and often involves risky situations where mistakes easily can lead to accidents. Deck crew working on the deck in a cargo operation is such a high complexity (and very risky) situation. 4 RESULTS The results are divided into two parts; one about the result from the interviews and one addresses the result of the HTA. CHALMERS, Shipping and Marine Technology, Master’s Thesis NM-15/46 35 Results from the interview investigation The analysis of the interview has been divided into three areas with the following subareas: 1. Challenges for the wind offshore industry 2. Near-shore and present situation a. Operational limitations and challenges b. Procedure and access systems 3. Remote offshore wind farms and future perspective a. Operational limitations for O&M b. Development of access systems 4.1.1 Challenges for the wind offshore industry On the first question all informants mention one word as a main challenge and that is “cost” in general and that is not only related to the O&M phase but also for the wind offshore industry as a whole. The industry needs to be competitive in the future in supplying an acceptable cost of energy for the electricity market According to the informants the industry is comparatively new, the wind farms have become bigger and further offshore. A reasonable fast development and the transfer from learning and experience in many areas like technical and even operational into new projects, is sometimes difficult which drives the costs upwards. As mentioned by one of the wind farm operator – “That is some