Deriving logistics decision variables and impact trade-offs to facilitate sustainable maintenance logistics for offshore wind farms

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Deriving logistics decision variables and impact

trade-offs to facilitate sustainable maintenance

logistics for offshore wind farms

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ABSTRACT

Extant research suggests that conducting logistical activities during the operations and maintenance phase of offshore wind farms is a costly, ecologically- and socially impacting endeavour. Hence, sustainability, i.e. the interplay of economical-, environmental- and social effects of decisions, requires consideration in this context. However, little is yet known about which decision variables and trade-offs between sustainability consequences need to be considered by the responsible firms, in order to attain sustainable logistics. Therefore, this research aims to develop comprehensive and empirically valid frameworks of sustainable maintenance logistics decision variables and sustainability impact trade-offs, related to these increasingly important assets.

By interviewing a wide variety of practitioners, this research shows that, amongst others, wind farm owners, maintenance- and logistics service providers and fleet managers together constitute a well organized maintenance logistics network, in which these firms need to seamlessly cooperate to ensure maximum electricity production revenues. Furthermore, it can be derived that within these networks numerous decisions have to be made on ‘transport & materials handling’, ‘warehousing & inventory management’, ‘information flow management’ and ‘packaging’. This research also reveals that in declining order of significance, particularly the former three areas contain decisions and trade-offs that influence firms’ sustainability performance. Specifically, critical decisions relate to which transport methods to employ and whether or not to share resources related to warehousing and inventory management or information, within or across maintenance logistics networks of wind farms. However, while safety is a non-discussable pre-condition, generally a financial-, rather than an environmental- or social-, impact orientation is found to be prevailing in the decisions. Simultaneously this study highlights that the significance of the decisions and trade-offs depends considerably on the existence of contextual variables. Finding an optimum by trading-off sustainability impacts is thus shown to be not straightforward and optimal solutions vary for different contexts. The list of known contextual variables is extended with factors such as the maintenance scope, wind farm ownership structure and the warranty-/subsidy period.

Ultimately, this research validates and extends the sparse and dispersed extant studies within this emerging research field. Furthermore, this research provides practitioners and researchers with incentives and insights required in order to make decisions, further develop conceptual- and mathematical models and supporting theories, which holistically establish and increase economical-, environmental- and social sustainability of maintenance logistics activities and decisions for offshore wind farms.

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ACKNOWLEDGEMENT

Dear reader,

Before you lies the MSc thesis report resulting from the research on sustainable maintenance logistics for offshore wind farms, which I conducted in order to complete the MSc Technology & Operations Management at the University of Groningen and the MSc Operations & Supply Chain Management at the Newcastle University. With the completion of this research there has come an end to my time as a student, a journey that I can look back upon with great pleasure. During my studies and industrial placements in diverse professional settings, I have had many enjoyable experiences with colleague students, teaching staff and companies and their operations processes.

Also during this final phase of my studies I have been able to explore a dynamic industry with fascinating assets and I have come into touch which numerous persons that have assisted me along the way. First of all, I would like to thank all the practitioners that were willing to share their knowledge on managing offshore wind farms and maintenance logistics with me. With their help I have been able to collect the information required to answer my research questions and thus to conduct this research. Furthermore, I wish to sincerely thank my supervisors from both universities and the Energy research Centre of the Netherlands (ECN) for their guidance and their efforts to challenge me to get the best out of this research and myself. From the University of Groningen, I would like to thank Dr. J. Veldman for his advice and supportive criticism at the times that I was struggling with my research. Next, from the Newcastle University I would like to thank Dr. J. Dong for his insightful comments on my various draft versions. My gratitude also goes to Mr. P. Eecen and Mrs. S. van Eijk of ECN. They provided me with the opportunity to apply and increase my knowledge and capabilities on operations and supply chain management, within the specific setting of the offshore wind industry. Moreover, their challenging but supportive comments on my work assisted me in increasing the research value. Finally, I would like to thank my family. Their support and faith throughout my studies has enabled me to dedicate myself to making the most out of my education. They also encouraged me when situations got tough and helped to put things into perspective when I needed it. Their guidance has been of tremendous value in getting me where I am today. Therefore, I would like to say:

“Soe ik alles witte wat te witten is, soe ik alles krije wat te krijen is, dochs sûnder jim leafde, begryp en bertrouwen, ik soe neat wêze.” 1

Joure, 8 December 2015

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8 December 2015

MSc thesis, MSc Technology and Operations Management University of Groningen, Faculty of Economics and Business.

MSc thesis, MSc Operations and Supply Chain Management Newcastle University, Newcastle University Business School.

Author/researcher S.B. (Sjirk Bareld) Bijma

Student number S2581159 (RUG) & B14061476 (NUBS) Address Scheen 94

8501 HJ Joure

E-mail s.b.bijma@student.rug.nl - s.b.bijma1@newcastle.ac.uk

Supervisor J. (Jasper) Veldman J. (Jingxin) Dong S. (Soledad) van Eijk Institution University of Groningen,

Faculty of Economics and Business

Newcastle University,

Newcastle University Business School Energy research Centre of the Netherlands (ECN) Address Nettelbosje 2 9747 AE Groningen 5 Barack Road

Newcastle upon Tyne, NE1 4SE

Westerduinweg 3 1755 LE Petten E-mail j.veldman@rug.nl jingxin.dong@newcastle.ac.uk vaneijk@ecn.nl

All rights reserved. No parts of this publication may be reproduced, stored in an unauthorized retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior

written permission of the author/researcher.

During this research due care has been taken in processing the information provided by external parties and in ensuring their confidentiality. As such any transcripts of information provided by these parties are not enclosed in this report. In the

eventuality an external party feels offended or if a party experiences improper use of the data provided by him/her, then

Deriving logistics decision variables and impact

trade-offs to facilitate sustainable maintenance

logistics for offshore wind farms

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LIST OF ABBREVIATIONS

BoP Balance of plant (i.e. foundation, electricity substation and -cables)

CO2 Carbon dioxide

CTV Crew transfer vessel

IMSP Independent maintenance service provider LSP Logistics service provider

MW Megawatts

NOx Nitrogen oxides

OA&SP Offshore accommodation and service platform O&M Operations and maintenance

OEM Original equipment manufacturer

OWF Offshore wind farm (i.e. all components of an offshore wind farm: BoP and turbine) ROV Remotely operated vehicle

SLSP Specialized logistics service provider

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LISTS OF FIGURES AND TABLES

List of figures

Figure 1 Logistics management elements and research scope (adjusted from Ballou, 2004)... 5

Figure 2 Sustainability elements (Carter & Rogers, 2008)... 6

Figure 3 Initial conceptual framework of SMLDV’s... 8

Figure 4 Logistics network layout for OWF’s (GL Garrad Hassan, 2013a) ... 10

Figure 5 Maintenance logistics framework for OWF’s (Shafiee, 2015)... 10

Figure 6 Final conceptual framework of SMLDV's for OWF’s... 13

Figure 7 In-depth field study structure & components... 17

Figure 8 Research model... 17

Figure 9 Maintenance logistics network for OWF’s... 23

Figure 10 Warehouse, inventory & human resource centralization & decentralization options... 26

Figure 11 Sustainability trade-offs & contextual factors: warehousing & inventory management consolidation... 39

Figure 12 Sustainability trade-offs & contextual factors: transport mode selection / investment... 43

Figure 13 Sustainability trade-offs & contextual factors: information sharing... 45

Figure 14 Final empirical framework of SMLDV’s for OWF’s... 48

List of tables

Table 1 Grouped logistics management elements ... 5

Table 2 Breakdown of sustainability elements (adjusted from Labuschagne & Brent, 2005) ... 6

Table 3 Decision variables for sustainable logistics discussed in extant research ... 14

Table 4 Research design selection (adjusted from Handfield & Melnyk, 1998) ... 16

Table 5 Industry practitioner interviewee overview ... 19

Table 6 Additional data sources ... 20

Table 7 Research quality assurance measures ... 21

Table 8 Contextual variables affecting the maintenance logistics network composition ... 24

Table 9 Maintenance logistics decision variables: warehousing & inventory management ... 27

Table 10 Maintenance logistics decision variables: transport & materials handling ... 30

Table 11 Maintenance logistics elements: relative sustainability impacts ... 38

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INTRODUCTION

1.

In efforts to expand energy production, nowadays the potential of offshore wind farms (OWF’s) is increasingly sought after (Bilgili, Yasar, & Simsek, 2011; Leung & Yang, 2012). For instance, the Dutch government aims to develop multiple new OWF’s in the near future, expanding the national production from 228 megawatts (MW) in 2014 to 4.450MW in 2023 (Ministry of Infrastructury and Environment & Ministry of Economic Affairs, 2014). Similar developments are also noticeable on a European scale (Bilgili et al., 2011; EWEA, 2013).

Managing OWF’s during their lifecycle involves numerous hand-offs between and collaboration amongst firms, such as component-, civil-, maintenance contractors, OWF owners and logistics service providers (e.g. see Joschko et al., 2015; Markard & Petersen, 2009; Utne, 2010; Wieczorek et al., 2013). Combined their responsibilities and interrelationships form nodes and linkages that together appear to constitute a complex logistics network. In the context of managing OWF’s, a logistical network is defined here as the set of firms involved in the onshore and offshore logistics management processes of planning, implementing and controlling the flow and storage of goods, services and related information (Lambert & Cooper, 2000). An aspect that increasingly attracts attention regarding logistics is sustainability. In fact, scholars argue that the consideration of economic-, environmental- and social- impacts of logistics decisions should be embedded within the design and management of logistics networks and processes (e.g. see Carter & Rogers, 2008; Neto, Bloemhof-Ruwaard, van Nunen, & van Heck, 2008; Seuring & Müller, 2008b). In this research the decisions concerning logistics that affect these sustainability areas are referred to as sustainable logistics decision variables. However, little is yet known on how these specific logistics networks of OWF’s operate and which decision variables and trade-offs existent therein need to be considered in order to establish sustainability in logistical operations in the OWF context. This research addresses these issues for a key phase in an OWF’s lifecycle, namely the operations and maintenance (O&M) phase. Logistics in this phase is also known as ‘maintenance-’ or ‘service’ logistics (Shafiee, 2015)2_.

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Clarifying insights regarding sustainable logistics are provided by Wu & Dunn (1995), Carter & Jennings (2002), Carter & Rogers (2008) and Dey, LaGuardia, & Srinivasan (2011). They concur that logistics strongly contributes to a firm’s economic-, environmental- and social impact and therefore practitioners should aim to achieve sustainable logistics. In this respect several decision variables have to be considered, such as inventory positioning, transportation mode selection and many more (Dey et al., 2011; Wu & Dunn, 1995). Furthermore, Neto et al. (2008) and Hassini, Surti, & Searcy (2012) highlight that designing and managing sustainable logistics (networks) inevitably requires trade-offs between the elements of sustainability, as the best performance on all elements is hardly attainable. None of these studies, though, focuses on OWF’s, logistics for offshore assets or maintenance logistics in general.

Ultimately, however, the body of knowledge on maintenance logistics for OWF’s, let alone sustainable logistics, is still in its infancy. Apart from the recent studies cited above, little research has been performed on these topics. This can be considered problematic as maintenance logistics is argued to impact significantly on the profitability of OWF’s (e.g. see Karyotakis, 2011; Shafiee, 2015). Indeed it can account for approximately ten per cent of the substantial expenditure levels incurred in managing such assets (Madariaga, De Alegría, Martín, Eguía, & Ceballos, 2012). Moreover, offshore logistics for OWF’s can negatively impact on the environment, as these logistical activities have been identified to deteriorate the function and stability of marine ecosystems (Arvesen & Hertwich, 2012). Hence, consideration of sustainability within maintenance logistics for OWF’s seems imperative. However, although Shafiee (2015) highlights decision variables for maintenance logistics he does not indicate how these variables relate to the three sustainability elements. Moreover, Neto et al. (2008) and Pagell and Shevchenko (2014) find that, generally, few studies exist that advance our understanding of how logistics functions should be designed in order to be considered sustainable. Similarly Gunasekaran & Spalanzani (2012) state that too little attention has been paid to sustainable logistics and argue that additional strategic frameworks should be developed that are concerned with embedding sustainability within logistics. Studying sustainable maintenance logistics for OWF’s contributes to this request when enabling theoretical generalization of such a framework developed for the OWF context. However, it also addresses the request by Hassini et al. (2012) for more industry specific research in this research field. Finally, Shafiee (2015) asserts that, while good practice on maintenance logistics for OWF’s exists, little has been actually reported upon in literature. As result little practice-based information is available to scholars to build further knowledge upon. Therefore, it is suggested to complement extant theories with insights from practice through interviewing experts (Shafiee, 2015). Accordingly, an empirical research on sustainable maintenance logistics for OWF’s can enrich existing theoretical insights. Ultimately, the identified gaps in academic literature for which this research can prove beneficial, are summarized as follows:

§ A lack of strategic frameworks covering decision variables for logistics management and their relationships with economic-, environmental- and social sustainability, which could facilitate understanding and consideration of embedding sustainability within logistics related decisions.

§ Limited theoretical discussions on the sustainability considerations within decisions regarding maintenance logistics for OWF’s.

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To conclude, in the light of the growing focus on OWF’s as means of energy production and the little scholarly knowledge currently available on the maintenance logistical network and sustainable logistics practice of these increasingly important assets, this research aims to contribute both to practice and theory. Specifically, the research objective is to:

Develop comprehensive and empirically validated frameworks of the sustainable maintenance logistics decision variables (SMLDV’s) and the involved sustainability impact trade-offs relating to

the O&M phase of the OWF lifecycle.

The methodology adopted to achieve this objective consists of two phases. First, a literature study is performed in order to identify SMLDV’s described in general (maintenance) logistics management- and sustainable logistics literature as well as those described in the few studies focussed on OWF’s. This will result in a conceptual framework of SMLDV’s potentially relevant to OWF’s. Subsequently, these SMLDV’s will be empirically validated and complemented with findings drawn from semi-structured interviews with practitioners in the offshore wind industry. By mapping the decision variables together with the various responsibilities in the logistical network of the O&M phase, this research aims to provide a holistic sustainable maintenance logistics overview. Such an overview could aid in managing and reducing the substantial expenditures and environmental- and social risks seemingly involved in this context and therefore could contribute to making this energy source truly sustainable. Furthermore, through theoretical generalization this study can aid in the development of sustainable logistics management frameworks requested by other scholars, as discussed earlier. Finally, such an overview can form a stepping-stone for identifying new important topics for research in this emerging industry and academic field.

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THEORETICAL FRAMEWORK

2.

The first research phase consists of a literature study that should result in a conceptual framework of SMLDV’s that can be relevant in the O&M phase of an OWF lifecycle. This framework can then subsequently be detailed, complemented and validated through an empirical study. To achieve this initial objective, the following question should be answered:

What are the sustainable logistics decision variables, discussed in extant literature, that can be relevant in the context of maintenance logistics for OWF’s?

In the following paragraphs the answer to this question will be gradually developed. Firstly, an elaboration is provided on what logistics management entails in the context of this research. Thereafter logistics management is discussed from the sustainability perspective that is increasingly adopted by academics. Based on this discussion an initial conceptual framework of SMLDV’s will be presented. Subsequently the scope is narrowed to logistics in the O&M phase of an asset lifecycle, which is the focus of this research. The final paragraphs focus on (sustainable) maintenance logistics for OWF’s. Additionally, several contextual variables will be introduced that should be considered when taking maintenance logistics decisions for OWF’s. Ultimately, by combining these paragraphs the initial conceptual framework of SMLDV’s will be refined, thereby answering the question posed above.

LOGISTICS MANAGEMENT

2.1

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Logistics management elements from Ballou (2004)

Grouped logistics management elements

Grouping rationale based on Bozarth & Handfield (2006) and Visser & van Goor (2011)

Transportation _{Transportation &} Materials handling

These elements concern activities and equipment employed to move parts, tooling and human resources across locations.

Materials handling

Warehousing _{Warehousing &}

Inventory management

Both elements concern activities and facilities used to store parts, tooling and human resources. Finished goods inventory

Packaging Packaging Only concerned with packaging of parts and tooling.

Distribution planning

Information flow management

Elements are concerned with information preceding, accompanying or following the physical flow of parts, tooling and human resources.

Order processing Customer service

Table 1 Grouped logistics management elements

Although arguably the OWF logistics network definition provided earlier bears similarity to the definition of supply chain management in Lambert & Cooper (2000), the use of this term is refrained from. This research is concerned with logistical processes, rather than all business processes included in supply chain management. However, where appropriate insights will be drawn from this related research field. Furthermore, textbook explanations of the logistics management elements will not be provided here. Rather the reader is referred to Bozarth & Handfield (2006) and Visser & van Goor (2011). Instead these elements will be discussed from a sustainability perspective.

SUSTAINABLE LOGISTICS

2.2

The concept of sustainability is most often described as the utilization of resources to meet present needs, in a manner that does not compromise the ability of future generations to meet their needs (Carter & Rogers, 2008). Following Chandima Ratnayake & Markeset (2012) it concerns balancing

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welfare and wellbeing advantages for society and firms if it is strategically embedded and focussed on activities that firms can actually affect, namely their core processes (Porter & Kramer, 2006). In the logistics context, sustainability increasingly attracts scholarly attention (Seuring & Müller, 2008a; Winter & Knemeyer, 2013). According to Carter & Rogers (2008) sustainability can be operationalized for logistics management purposes as the strategic integration of economic-, environmental- and social objectives in the intra and inter-firm logistical processes and decisions (see figure 2). As such

Hassini et al. (2012) find that it implies trying to achieve multiple goals, which potentially conflict. For instance, they state that minimizing environmental- and social burdens can result in poorer economic performance due to the costs of impact reduction actions. Hence, trade-offs between sustainable logistics objectives can exist (Neto et al., 2008). Examples of sustainable logistics goals are cost efficient warehousing (economical), carbon dioxide (CO2) emission reduction in transport

(environmental) and safety assurance for persons involved in logistical activities (social) (Dey et al., 2011; Wu & Dunn, 1995). Labuschagne & Brent (2005) provide a more extensive overview of the sub-elements of each sustainability element (see table 2). The last column provides an operationalization of the sub-elements in the context of logistics. The operationalization’s are derived by inserting the sustainability elements identified for logistics in general (e.g. see Carter & Jennings, 2002; Gunasekaran & Spalanzani, 2012; Wu & Dunn, 1995) into the corresponding sustainability sub-elements defined by Labuschagne & Brent (2005). As reported by Kudla & Klaas-Wissing (2012) many activities can be conducted in order to attain sustainable logistics but foremost it requires acknowledgement of its criticality and cooperation between parties in a logistics network.

Sustainability elements Sub-elements Sub-elements operationalized in the logistics context

Economical sustainability

Financial health & benefits Profitability of the focal logistics provider

Economic performance Perceived profitability by the logistics stakeholders Trading opportunities Financial vulnerability and risks for the logistics network

Environmental sustainability

Air resources Reduction of polluting substance emission (e.g. CO2) by storage and transport of parts, tooling and human resources Water resources Reduction of water quality deterioration caused by transport

of parts, tooling and human resources over sea Land resources Reduction of eco-toxicity (e.g. oil leakage) caused by

storage and transport of parts, tooling and human resources Mineral and energy

resources

Reduction of fossil fuel usage by transport methods and storage facilities of parts, tooling and human resources

Social sustainability

Internal human resources Stability of employment, safety and ethics assurance External population Reduction of community burden (e.g. noise pollution) Stakeholder participation Transparent provision of logistics related information Macro social performance Contribution to regional or national sustainability objectives Table 2 Breakdown of sustainability elements (adjusted from Labuschagne & Brent, 2005)

Environmental

performance performance Social

D

Economic performance Sustainability

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DECISION VARIABLES FOR SUSTAINABLE LOGISTICS

2.3

According to Dey et al. (2011) and Wu & Dunn (1995) it is through decisions made on the logistics management elements, introduced earlier, that firms can influence how their logistics function contributes to achieving sustainability. As stated before, these decisions that can impact on one or more of the sustainability elements are here referred to as sustainable maintenance logistics decision variables (SMLDV’s). Next those SMLDV’s discussed in general logistics management literature will be elaborated upon in order to progress the initial understanding of potential SMLDV’s for OWF’s A first frequently discussed decision variable is transportation and materials handling. In their respective papers Carter & Rogers (2008), Dey et al. (2011) and Wu & Dunn (1995) argue that firms must carefully consider the transport mode, quantity and frequency because emissions of greenhouse gasses resulting from logistical activities can significantly contribute to environmental pollution and deterioration of the human wellbeing. Concurrently they find that costs must be taken into account, as different transport methods or quantities often involve higher or lower expenditure levels. Finally, concerning social sustainability Carter & Jennings (2002) find that safe operation of transportation equipment and minimization of community disturbance (e.g. noise pollution) should be addressed. Another decision variable affecting all three sustainability elements is warehousing and inventory management, i.e. the processes of storing, repackaging, sorting and centralizing resources (Bozarth & Handfield, 2006). According to Dey et al. (2011) decisions to keep inventory levels at a minimum can increase cost efficiency through lower holding costs and reduce ecological impact, as smaller warehouses can be used with lower energy needs. While Carter & Jennings (2002) take a social perspective and argue that consideration of safety for warehouse employees is crucial (e.g. in dealing with hazardous materials). This decision variable is also closely linked with transportation and materials handling, as, for instance, decisions to centralize or decentralize warehouses and their location affect decisions on the method, frequency and length of transportation (Aronsson & Brodin, 2006; Bozarth & Handfield, 2006; Wu & Dunn, 1995).

Thirdly, attention should be paid to packaging. Wu & Dunn (1995) argue that decisions on the size, shape and the material type of a package influence the transport characteristics packages and thereby the logistics costs. Next, scholars concur that efforts to provide honest labels, reduce packaging needs and to recycle packaging material are required, thereby simultaneously contributing to economical-, environmental- and social sustainability (Carter & Jennings, 2002; Gunasekaran & Spalanzani, 2012). A final important logistics management element that can impact on the sustainability aspects concerns the flow of logistics related information (e.g. routing, planning, etc.) prior to, alongside and/or after the movement of goods within a logistics network (Dey et al., 2011). In particular, Dey et al. (2011) and Wu & Dunn (1995) find that it is crucial to timely provide logistics stakeholders with accurate information. This aids in improving the utilization of storage- and transportation space, thereby reducing logistics cost and emission of polluting substances. Finally, Pagell & Wu (2009) identify a social benefit, as information sharing aids in preventing stakeholder abuse.

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SUSTAINABLE MAINTENANCE LOGISTICS

2.4

This research addresses logistics in the O&M phase of an asset’s lifecycle, i.e. ‘maintenance’ logistics. This form of logistics is needed to enable maintenance actions aimed at retaining assets in their desired operating state (Murthy, Solem, & Roren, 2004; Shafiee, 2015). In practice this involves activities such as transportation and ‘storage’ of maintenance technicians, tooling and spare parts as well as providing a supporting infrastructure, like information systems, transportation means or maintenance facilities (Murthy et al., 2004). DHL (2015) highlights that maintenance logistics has become increasingly important in practice as result of significant expenditures and risks nowadays involved in managing the flow of maintenance goods and information. Next a discussion follows of decision variables for maintenance logistics and how these are linked to sustainability.

Firstly, concerning spare parts management (i.e. warehousing and inventory management decisions), Huiskonen (2001) and Kennedy, Patterson, & Fredendall (2002) note that decisions on storage quantities and locations are not trivial, as the demand for spare parts is often sporadic; holding- and acquisition costs of parts are often substantial; and the economic effects of stock-outs can be significant. Kutanoglu & Lohiya (2008) and Murthy et al. (2004) add that these warehousing and inventory management decisions also require careful consideration of transportation modes, times and costs for movements between warehouses and a location of need (e.g. an asset site). Overseeing all, the authors covering such decisions touch upon economical sustainability. Environmental and social aspects, though, have seemingly not yet been thoroughly described. However, one could intuitively argue that concerning sustainability in the maintenance logistics context, similar decisions regarding

Sustainable logistics decision variables

Transportation & Materials handling

§ Transportation mode(s) & quantity

§ Transportation frequency

§ Handling equipment

Warehousing & Inventory management

§ Warehouse location(s) & quantity

§ Warehouse (de-) centralization

§ Inventory location(s) & quantity

§ Human resource location(s)

Packaging

§ Packaging size(s) & shape(s)

§ Packaging material(s)

§ Label design & usage

Information flow management

§ Routing and capacity information

§ Coordination of transport and storage

§ Sustainability performance information

Sustainability elements

Economical sustainability

§ Financial health & benefits

§ Economic performance § Trading opportunities Environmental sustainability § Air resources § Water resources § Land resources

§ Mineral and energy resources

Social sustainability

§ Internal human resources

§ External population

§ Stakeholder participation

§ Macro social performance

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warehousing and inventory management and transportation and materials handling have to be made as those for logistics in general, outlined earlier.

Furthermore, decisions should be made on ‘stocking’ and using supporting information systems in order to effectively manage the logistics-related information flow. According to Wu & Dunn (1995) such a system can be applied to determine efficient allocations of spare parts inventory quantities, as result of which unnecessary transport movements can be eliminated. This yields sustainable maintenance logistics as seen from all three sustainability perspectives, as costs, CO2 emission and

community burden can be reduced.

Finally, little academic research has been published on packaging issues within the maintenance logistics context. However, similar to the warehousing and transportation decisions, it is not unimaginable to apply the SMLDV’s identified from the general logistics context to maintenance logistics. For instance, decisions with regards to packaging of spare parts can impact on economical- and environmental sustainability, when opting for minimalistic packaging.

SUSTAINABLE MAINTENANCE LOGISTICS FOR OWF’S

2.5

Logistical operations for OWF’s are complex, costly, and potentially environment- and society harming endeavours (Arvesen & Hertwich, 2012; Halvorsen-Weare, Gundegjerde, Halvorsen, Hvattum, & Nonås, 2013; Scholz-Reiter, Heger, Lütjen, & Schweizer, 2011; Shafiee, 2015), thus requiring adequate consideration of OWF stakeholders. Especially effective and efficient management of maintenance and the related logistics is crucial for the cost efficiency of the asset, as the O&M phase can last for twenty years (Shafiee, 2015). It is important to note that, although OWF’s are situated offshore, stakeholders operate both onshore and offshore (Joschko et al., 2015). Figure 4 provides a rough overview of the geographical layout of a maintenance logistics network for OWF’s. Here onshore maintenance logistics, for instance, comprises landside warehousing and transportation of OWF spare parts. Examples of offshore activities are the transport of spares, tools and maintenance specialists, either by vessel or helicopter to the OWF.

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Concerning the sustainability impact of maintenance logistics for OWF’s, useful insights can be drawn from lifecycle analysis research, such as the studies by Arvesen, Birkeland, & Hertwich (2013) and Arvesen & Hertwich (2012b). These scholars show that particularly the offshore logistical activities can negatively affect the environment through the emission of polluting substances, such as CO2 and nitrogen oxides (NOx), by vessels. Next to environmental impacts, social- and economical

impacts can also result from offshore logistics. For instance, Dai, Ehlers, Rausand, & Utne (2013) and Shafiee (2015) highlight that there are considerable risks of collisions of vessels with wind turbines or their supporting infrastructure. Such collisions can cause harm to people and marine ecology and can result in significant financial expenditures for repairing the OWF and transport means. Furthermore, extant work relates more specifically to economical sustainability. The research by Shafiee (2015), for

Figure 4 Logistics network layout for OWF’s (GL Garrad Hassan, 2013a)

Maintenance logistics for OWF’s

Strategic echelon Tactical echelon Operational echelon

Wind farm design for reliability Location/Capacity of

maintenance accommodations Maintenance strategy selection Outsourcing decisions

Spare parts management Maintenance support organization

Purchasing and leasing decisions

Maintenance scheduling Routing of maintenance vessels Performance measurement

Figure 5 Maintenance logistics framework for OWF’s (Shafiee, 2015)

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example, suggests the importance of taking a financial outlook towards maintenance logistics for OWF’s since substantial costs and economical risks are involved. Particularly he finds that adequate spare part levels should be maintained, because additional downtime due to spare part unavailability can cause significant financial losses. On the other hand he states that excess spares also result in unwanted costs. The environmental impact of these warehousing and inventory management decisions, however, (e.g. energy consumption or land use by warehousing), as highlighted by Wu & Dunn (1995), are neglected in this discussion. Similarly fleet management research, which relates to transportation and materials handling decisions, commonly aims for cost optimization rather than achieving optimal or acceptable performance on economic, environmental or social sustainability in a holistic manner (e.g. see Besnard et al., 2013; Dalgic, Lazakis, Dinwoodie, et al., 2015; Dalgic, Lazakis, Turan, et al., 2015; Halvorsen-Weare et al., 2013).

Overseeing all, however, academic discussions on maintenance logistics in the context of OWF’s are sparse. Even more so are studies that frankly discuss how maintenance logistics decisions affect the economical-, environmental- and social aspects of sustainability.

CONTEXTUAL VARIABLES OF MAINTENANCE LOGISTICS FOR OWF’S

2.6

Despite being variables, the SMLDV’s can be constrained or affected by decisions made in different lifecycle phases or on aspects other than logistics. Furthermore, there might be variables, like the weather, which are hard or impossible to influence by the parties responsible for maintenance logistics of OWF’s. In this paragraph these contextual variables will be briefly outlined.

Service agreements & maintenance strategies - Firstly, maintenance logistics providers cannot make decisions independently from customer characteristics and requirements. This is because maintenance and the related logistical activities are commonly carried out via service agreements (Jin, Tian, Huerta, & Piechota, 2012; Kutanoglu & Lohiya, 2008; Shafiee, 2015). Hence, decisions regarding maintenance logistics are constrained by customer (read OWF) locations, required response times, and the agreed upon service levels (e.g. OWF availability) (GL Garrad Hassan, 2013a). In addition, the maintenance logistics decisions are influenced by the adopted maintenance strategy (Karyotakis, 2011; Kennedy et al., 2002), which is often aimed at maximizing OWF availability and minimizing maintenance costs (Shafiee, 2015). In this respect, decisions to correctively repair or preventively replace parts determine which parts should be stocked, in what quantity and if they should be located closely to the OWF in order to limit downtime. Moreover the frequency of maintenance naturally determines the frequency at which transport between the resource locations and OWF’s occurs. Consequently, although certain spare parts policies on themselves could be considered less costly and or more environmentally friendly (e.g. when storing only a few spare parts), these policies might be unsuitable to comply with the service agreements.

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OWF location, size and design - At the outset of the OWF lifecycle lie the decisions where to locate the OWF, how many turbines to place and which type of OWF components to use, which, amongst others, are based on wind speeds, installation costs and regulations (e.g. see Gerdes, Albrecht, & Zeelenberg, 2005). In turn these variables influence maintenance logistics decisions (Shafiee, 2015; Tracht, Westerholt, & Schuh, 2013). For instance, they affect decisions on where to locate warehouses; which port(s) to use for hand-offs between onshore and offshore logistics; and which transportation methods to employ (Douglas-Westwood, 2006; Gerdes et al., 2005; GL Garrad Hassan, 2013a, 2013b). Moreover, if the OWF location is such that the transit time between onshore resources and the OWF becomes so long that too little time remains available for maintenance, decisions must be made on using an offshore base for storing spares and tooling and as a temporary accommodation for technicians (GL Garrad Hassan, 2013a; Shafiee, 2015). Additionally, if transit times become too long this can lead to increased physical burden on the technicians. Hence, then there should be facilities for these specialists to rest.

Weather conditions – Finally, weather conditions greatly influence maintenance logistics decisions (El-Thalji & Liyanage, 2012; GL Garrad Hassan, 2013a; Karyotakis, 2011). For example, wave heights, wind speeds, visibility etc. determine whether certain transportation methods can be utilized due to physical constraints or unacceptable safety hazards (El-Thalji & Liyanage, 2010; GL Garrad Hassan, 2013b; Herman, 2002). Here also lies a link with maintenance strategy adoption. This is because, in fact, severe weather conditions might inhibit any access to the OWF for a certain period of time and thus restrict any form of maintenance (Bussel van & Zaaijer, 2001). Consequently, maintenance providers might opt for conducting preventive maintenance during periods of good weather conditions in order to prevent breakdowns that are costly or impossible to repair during periods with poor weather conditions (e.g. the winter). However, the required spare parts, tooling and human resources and transportation methods should then also be available.

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THEORETICAL CONTRIBUTION

2.7

In brief, in extant research the importance of embedding sustainability within logistics is increasingly discussed. The studies also highlight several logistics decision variables, which impact on economic-, environmental- and social aspects of sustainability. However, when considering general maintenance logistics and maintenance logistics for OWF’s, sustainability has not entered scholarly discussions yet or only to a limited extent. This is an ill state-of-art because the studies by Arvesen & Hertwich (2012b), Karyotakis (2011) and Shafiee (2015) suggest that maintenance logistics in the OWF context can indeed impact on any of the three sustainability aspects. Based on the literature study, table 3 summarizes the grouped logistics decision variables for sustainable logistics, which have been explicitly addressed in extant academic work. References are only added to this table if the respective study discusses how and why relationships between logistics decisions and sustainability impacts exist and not merely state that there is an economical-, ecological- and or social impact of a logistical activity. Hence, these studies show how logistics decisions can be made towards establishing sustainability within logistics processes. Ultimately, this table then also highlights the gap in literature, which this research aims to address.

Sustainable maintenance logistics decision variables

Transportation & Materials handling

§ Onshore & offshore transportation mode(s) & quantity

§ Onshore & offshore transportation frequency

§ Onshore & offshore handling equipment

§ Outsourcing transportation & materials handling

Warehousing & Inventory management

§ Warehouse location(s) & quantity

§ Warehouse (de-) centralization

§ Spare parts & tools location(s) & quantity

§ Human resource / maintenance accommodation location(s)

§ Outsourcing warehousing & inventory management

Packaging

§ Packaging size(s) & shape(s)

§ Packaging material(s)

§ Label design & usage

Information flow management

§ Routing and capacity information

§ Coordination of transport and storage

§ Sustainability performance information

Sustainability elements

Economical sustainability

§ Financial health & benefits

§ Economic performance § Trading opportunities Environmental sustainability § Air resources § Water resources § Land resources

§ Mineral and energy resources

Social sustainability

§ Internal human resources

§ External population

§ Stakeholder participation

§ Macro social performance Service agreements Maintenance strategies OWF design & location Weather conditions Regulations

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Logistics management Maintenance logistics Maintenance logistics _{for OWF’s}

Logistics management

elements Econ. Envi. Soci. Econ. Envi. Soci. Econ. Envi. Soci.

Transportation & Materials handling ✓ ✓ ✓ ✓ ✓ Warehousing & inventory management ✓ ✓ ✓ ✓ ✓ Packaging ✓ ✓ ✓ Information flow management ✓ ✓ ✓ ✓ ✓ ✓ References

(Aronsson & Brodin, 2006; Bretzke & Barkawi,

2013; Carter & Jennings, 2002; Carter & Rogers,

2008; Ciliberti et al., 2008; Dey et al., 2011; Kudla & Klaas-Wissing, 2012; Pagell & Wu, 2009;

Wu & Dunn, 1995) (Huiskonen, 2001; Kennedy et al., 2002; Wu & Dunn, 1995) (Besnard et al., 2013; Dalgic, Lazakis, Dinwoodie, et al., 2015; Dalgic, Lazakis, Turan, et

al., 2015; Shafiee, 2015)

Table 3 Decision variables for sustainable logistics discussed in extant research

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RQ. What are the sustainable maintenance logistics decision variables and their sustainability impact trade-offs, which have to be considered by the parties who form a maintenance logistics network to

ensure sustainable logistics in the O&M phase of OWF’s?

SQ1. Which parties have responsibilities for maintenance logistics activities and decisions during the O&M phase of OWF’s and how do they together constitute a maintenance logistics network?

SQ2. What are the maintenance logistics management processes occurring in practice during the O&M phase of OWF’s, where design and management decisions can impact on economic-, environmental- and social sustainability?

SQ3. How does the conceptual framework of sustainable maintenance logistics decision variables conform to the practice of maintenance logistics of OWF’s?

SQ4. What are the trade-offs regarding economic-, environmental- and social sustainability impacts within the sustainable maintenance logistics decision variables related to the O&M phase of OWF’s?

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RESEARCH METHODOLOGY

3.

In the following sections the research methodology of this study will be outlined. Specific attention is directed towards the research design, the data collection- and analysis approach and the methods through which the reliability and validity of this research are assured.

RESEARCH DESIGN

3.1

Recall that the research objective was to develop comprehensive and empirically valid frameworks of SMDLV’s and sustainability impact trade-offs that need to be considered during the O&M phase of OWF’s. In the first phase of this research, i.e. the literature study, this objective was partly achieved by developing a tentative framework based on extant theory (see figure 6). Next an empirical study was conducted to detail, extend and validate this framework. However, as the literature study revealed that little is known about SMLDV’s and their trade-offs for OWF’s, the empirical study had a strong exploratory character. Specifically, following the research phasing and design selection approach of Handfield & Melnyk (1998) (see table 4), the purpose of the empirical phase was thus to ‘describe’ and ‘map’ the decision variables, sustainability impacts and trade-offs for OFW’s that are actually considered by the network of responsible parties. In doing so, the ‘relationships’ between the decision variables, sustainability impacts and potential influential contextual variables were also identified and described. Regarding ‘mapping’ and ‘relationship building’, the main focus was on drawing clarifying overviews of the maintenance logistics network, decisions variables, trade-offs, contextual variables and the linkages between the latter three aspects. By deriving the findings from practice, the empirical validity of these descriptions and visual overviews was to be established. Ultimately, these insights were compared with the theoretical conceptual framework to discuss the implications of this research.

Table 4 Research design selection (adjusted from Handfield & Melnyk, 1998)

For exploratory studies focussed on ‘describing’ and ‘mapping’ phenomena and ‘identifying relationships' in their natural setting, an in-depth field study is appropriate (Handfield & Melnyk, 1998; Karlsson, 2009) (also see table 4). This method enabled gaining a detailed understanding of the

Research phase & purpose

(Exploration towards theory refinement) Research questions Research methods

1a. Discovery

• Uncover research areas

• Is there something interesting

enough to justify research? • Unfocussed field studies through observations & interviews

1b. Description

• Explore territory

• What is happening? • What are the key issues?

2. Mapping

• Identify / describe key variables • Draw maps of the territory

• What are the key variables, critical

themes, patterns, and categories? _{• In-depth field studies} through observations & interviews

3. Relationship building

• Improve maps by identifying linkages between variables

• What are the patterns or linkages between variables?

4. Theory validation

• Test the theory

• Did we get the behaviour that was

predicted by the theory? • Experiments, large sample surveys & structured interviews

5. Theory extension / refinement

• Expand the theory

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decision variables and trade-offs that are present in the O&M phase of OWF’s. Moreover, how these decisions account for economic-, environmental- and social sustainability impacts could be studied in greater detail. Here the overarching unit of analysis was maintenance logistics within the empirical context of managing OWF’s during the O&M phase. Subsequently, within this unit of analysis sub-contexts were defined, which in fact were the logistics management elements listed in table 1. Figure 7 visualizesthis particular structuring of the in-depth field study approach. Each sub-context was studied on its own and in relation to other sub-contexts by drawing from practitioners who are knowledgeable on these elements. This is also known as the Delphi method, which is elaborated upon next.

Summarizing the research design outlined above and following Verschuren & Doorewaard (2007) figure 8 represents this study’s research model, which also visualizes the research activity sequencing.

DATA COLLECTION

3.2

In order to answer explorative questions, such as the research questions of this study, Handfield & Melnyk (1998) find that particularly interviews with experts operating in the field is an suitable data collection technique. This approach also satisfied the request in existing OWF maintenance logistics literature to provide reports on the experiences of practitioners (e.g. see Shafiee, 2015). This approach, where the knowledge of experts is sought after, is also known as the Delphi method. Next, the applied

Figure 8 Research model

Logistics management

Sustainable logistics

Maintenance logistics

Maintenance logistics for OWF’s

Conceptual framework

In-depth field study: Wareh. & Inv. man.

In-depth field study: Packaging

Analysis results Di sc us si on & Co nc lu si on s Analysis results In-depth field study: Trans. & Mat. Hand.

In-depth field study: Inf. flow man.

Analysis results

Theoretical background

Empirical context: Operations & maintenance phase of offshore wind farm ‘x’

Unit of analysis: Maintenance logistics conducted by parties forming a maintenance logistics network Sub context 1: Transportation & Materials handling Sub context 2: Warehousing & Inventory management Sub context 3: Packaging Sub context 4: Information flow management

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3.2.1 Delphi method

The Delphi method is the process of accumulating experiences and judgements from experts on a certain phenomenon, through a series of data collection moments followed by feedback communicated by the researcher (Hsu & Sandford, 2007; Yousuf, 2007). Usually the Delphi method includes several rounds in order for the experts to reach a consensus. However, due to the exploratory nature of this research the objective was not necessarily to establish a consensus as much as it was to gain as many insights as possible on the views of practitioners on sustainable maintenance logistics for OWF’s. Hence this research was restricted to only one round of data collection, where it was attempted to collect data from as many practitioners as possible within this study’s pre-defined time frame. Each expert was subsequently provided with feedback in the form of a transcription of his or her own statements. Moreover, where relevant this transcription also included comments on conflicting statements within or across statements made by the practitioner(s). The Delphi method was especially beneficial for this research as this research required information and insights on SMLDV’s that were unavailable in literature and it required the identification of sustainability impact trade-offs made in practice (Linstone & Turloff, 1975; Yousuf, 2007). In addition, Okoli & Pawlowski (2004) showed the suitability of the Delphi method for framework development, as was aimed for in this research.

3.2.2 Interview approach

Regarding the Delphi method, 19 semi-structured interviews were conducted with practitioners from the offshore wind industry. This approach allowed for new but related topics to arise and be discussed during conversations, which often occurs and is required in explorative studies (Yin, 2009). Due to resource constraints only one researcher was present during the interviews. However, in order to assure that no relevant information was left undocumented the interviews were recorded and transcribed, if permission to do so was obtained from the interviewee. Transcription was carried out within thirty-six hours to ensure maximum recollection of the statements and the context in which they were placed as well as to ensure recall of possible visual cues. The topics and questions that were put forward during the interviews were documented in advance in an interview protocol (see appendix 1). This protocol, excluding the questions, was provided to each participant prior to the interview. At the start of each interview the participant was then asked to sign the consent form to confirm that he or she understood the purpose and process of the research and to give consent on the use of the interview transcripts for this research. The conversations lasted between 45 minutes and 1,5 hours and were conducted in the period of August until October 2015. Apart from one telephone interview all interviews took place at the offices of the interviewees, which also enabled making observations.

3.2.3 Expert selection

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maintenance logistics element(s). Furthermore, it was attempted to include parties with different maintenance logistics responsibilities in order to address different perspectives towards the topic of research. However, with respect to SQ1 and SQ2 on identifying the maintenance logistics decisions and responsible firms, only first-tier parties in the logistics network, as seen from the firm that owns and manages the OWF, were considered. This scope was adopted based on Lambert & Cooper (2000), who argue that it is erroneous to manage processes across all tiers. Moreover they find that particularly the first-tier parties impact on the focal process in the logistics network, in this case maintaining the OWF’s. Finally, practitioners were selected based on establishing a diversity of served OWF’s, to enable comparisons between different maintenance logistics concepts and contexts. Ultimately, 14 different European near-shore and far-shore OWF’s were referred to. Table 5 lists the consulted experts. Due to ethical and competitive concerns the interviewees were anonymized. For the same reason also all other potential references to the interviewees or the firms they work for (e.g. OWF names, installed capacities, revenues, places, vessels names etc.), were made anonymous.

Interviewee Organization type Position Relevant maintenance

logistics element

A Research institute

Confidential

T&MH, IFM B Windfarm owner/management T&MH, W&IM, IFM, P C Windfarm owner/management T&MH, W&IM, IFM, P

D Research institute IFM

E Consultancy T&MH, W&IM, IFM, P F Logistics service provider T&MH, W&IM, IFM, P G Windfarm owner/management T&MH, W&IM, IFM, P H Independent maintenance service provider T&MH, W&IM, IFM, P I Independent maintenance service provider T&MH, W&IM, IFM, P J Research institute T&MH, W&IM, IFM

K Research institute IFM

L Windfarm owner/management T&MH, W&IM, IFM, P M Logistics service provider T&MH, W&IM, IFM, P N Consultancy T&MH, W&IM, IFM, P O Port authority T&MH, W&IM, IFM P Independent maintenance service provider T&MH, W&IM, IFM, P Q Independent maintenance service provider T&MH, W&IM, IFM, P R Turbine OEM/maintenance service provider T&MH, W&IM, IFM, P S Windfarm owner/manager T&MH, W&IM, IFM, P

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triangulation and thereby enhance the construct validity of this research (Voss et al., 2002). The additionally employed sources are listed in table 63.

Title Type Creation date Access date Location

Sustainable service logistics for offshore

wind farms – Full proposal 2014 Research proposal 01-04-2014 22-06-2015 Confidential Harbour logistics during the operational

phase Business presentation N/A 24-08-2015 Confidential Offshore WIND Conference 2015 Industry conference N/A 12-09-2015 Amsterdam

Offshore Energy 2015 Industry conference & _exhibition N/A 14-09-2015 Amsterdam

Table 6 Additional data sources

DATA ANALYSIS

3.3

Following the collection of data a qualitative analysis was performed, as suggested by Miles & Huberman (1994). To this end the collected data was firstly reduced in order to highlight critical information. Subsequently the data was displayed in summarizing overviews in order to visualize the SMLDV’s and sustainability impact trade-offs found in practice. Finally, based on these overviews the conclusions of this research were drawn. In the first step, data reduction, deductive and inductive coding was applied. Specifically, the statements from interviews, observation descriptions and excerpts from reports and academic literature were summarized using first order descriptive codes. These descriptive codes were initially based on the concepts introduced in the theoretical framework. However, as the empirical study yielded additional SMLDV’s or factors influencing the relationship between maintenance logistics decisions and sustainability impacts, this list of codes was extended with appropriate codes inducted from these additional findings. Appendix 2 contains the ultimate list of descriptive codes and appendix 3 provides a few examples of the applied coding process. Afterwards, pattern matching was applied through comparing the codes across the different data sources. Ultimately, by means of this qualitative analysis it was possible to identify the empirical SMLDV’s and sustainability impact trade-offs related to the OWF context. Via visualizing these findings and comparing them with the theoretical framework, conclusions could then be derived to answer the main research question. Throughout this data analysis process, the supportive software “ATLAS.ti” was used for coding, pattern matching and creating data overviews.

RESEARCH QUALITY ASSURANCE

3.4

A key consideration throughout this research was to assure the quality of the collected data and the conclusions drawn from it, by drawing on relevant prescriptions by Karlsson (2009) and Yin (2009). First, concerning reliability, an interview protocol was used that outlined why and how the interviews should be conducted (see appendix 1). Secondly, in case of permission interviews were recorded and carefully transcribed. Finally, field-study databases were used to store and organize all theoretical and empirical findings. Next, internal validity was obtained by matching patterns across the statements

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made by the various practitioners. In addition, explanation building was applied to indicate why and how certain decision variables could impact on one or more of the sustainability areas as well as why and how trade-offs existed therein. Furthermore, to establish external validity, relevant theory was researched and applied to provide theoretical explanations for the findings. Secondly, multiple practitioners were selected based on their knowledge on maintenance logistics for different OWF’s. Hence, essentially multiple cases were discussed and thereby replication logic could be applied. Finally, to assure construct validity, first a chain of evidence was maintained by outlining the research objective, data collection- and analysis methods, the results and conclusions. Moreover, by comparing statements by multiple practitioners, data sources were triangulated. In addition, data collection method triangulation was applied by drawing data from interviews, site visits observations, reports and academic research. Thirdly, the interview protocol and questions went through an initial scan for mistakes and improvements via discussions with academic researchers and representatives from the industry. Finally, after the interviews, participants were debriefed and offered transcripts for reviewing and revising the findings. Table 7 summarizes the aforementioned quality assurance measures.

Quality aspect Measures

Reliability

§ Application of a strict interview protocol (see appendix 1)

§ Interviews were recorded and transcribed if permission was obtained

§ Theoretical and empirical findings were collected in an electronic field-study database Internal

validity

§ Pattern matching of experts’ statements on the same maintenance logistics elements

§ Explanation building through comparing empirical and theoretical findings External

validity

§ Use of practitioners with knowledge on one or more maintenance logistics element(s)

§ Application of replication logic by comparing statements from practitioners on the same maintenance logistics elements across different settings (e.g. different OWF’s)

Construct validity

§ Maintaining a chain of evidence through transparently outlining research objectives, data collection- and analysis methods, results and conclusions.

§ Data triangulation by interviewing multiple experts on maintenance logistics elements

§ Method triangulation: interviews, site visits, company reports & academic research

§ Check of interview protocol with academic researchers and industry representatives

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RESULTS

4.

Following the collection of data, this chapter presents the results. First the maintenance logistics network will be outlined in order to advance the understanding of how responsibilities for maintenance logistics are allocated amongst firms in the OWF industry (SQ1). In doing so the perspective of the OWF owner/manager as the focal organization is adopted (see also §3.2.3). Thereafter descriptive explanations of the empirical maintenance logistics decision variables and their sustainability impact will be given, thereby answering SQ2 & SQ3. Subsequently SQ4 & SQ5 are answered by presenting key offs regarding the SMLDV’s and the potential effect of contextual variables on these trade-offs. Throughout the following sections quotes from the interviews are used to clarify and emphasize findings. Capital letters refer to the origins of statements (see table 5).

MAINTENANCE LOGISTICS NETWORK

4.1

Confirming the research by GL Garrad Hassan (2013a) and Joschko et al. (2015), all interviewees concurred that multiple firms with various responsibilities are involved in the O&M phase of OWF’s. Firstly, the OWF owner/manager is the firm or consortium of firms that has ordered the construction of the OWF and will gain financial benefits from the OWF’s’ production. This party has the ultimate responsibility for and control over the OWF during its lifecycle and can decide to (partly) perform maintenance logistics internally or to outsource it to the firms introduced next (C, G & L). Commonly the owner will obtain a warranty period on OWF components, particularly for the turbine, during which original equipment manufacturers (OEM’s) will conduct maintenance logistics activities and ensure a pre-determined OWF availability level (E, N & R). Often there are different OEM’s for the turbine, foundation, electricity substation and array cables. These latter three components combined are also known as the Balance of Plant (BoP) and are in some cases maintained by one firm. B, E and K noted that both during and after the warranty period OEM’s are the main supply source because of their specialized knowledge. Since a few years, though, third party spare part resellers are also entering the market. These serve as supermarkets for spares from different OEM’s and cause more competition to exist (B). Furthermore, B, J and N noted that there are 2nd_{tier parts suppliers supplying}

Deriving logistics decision variables and impact trade-offs to facilitate sustainable maintenance logistics for offshore wind farms

Deriving logistics decision variables and impact

trade-offs to facilitate sustainable maintenance

logistics for offshore wind farms

ABSTRACT

ACKNOWLEDGEMENT

8 December 2015

Deriving logistics decision variables and impact

trade-offs to facilitate sustainable maintenance

logistics for offshore wind farms

TABLE OF CONTENTS

LIST OF ABBREVIATIONS

LISTS OF FIGURES AND TABLES

List of figures

List of tables

INTRODUCTION

1.

THEORETICAL FRAMEWORK

2.

LOGISTICS MANAGEMENT

2.1

SUSTAINABLE LOGISTICS

2.2

DECISION VARIABLES FOR SUSTAINABLE LOGISTICS

2.3

SUSTAINABLE MAINTENANCE LOGISTICS

2.4

SUSTAINABLE MAINTENANCE LOGISTICS FOR OWF’S

2.5

CONTEXTUAL VARIABLES OF MAINTENANCE LOGISTICS FOR OWF’S

2.6

THEORETICAL CONTRIBUTION

2.7

RESEARCH METHODOLOGY

3.

RESEARCH DESIGN

3.1

DATA COLLECTION

3.2

3.2.1 Delphi method

3.2.2 Interview approach

3.2.3 Expert selection

DATA ANALYSIS

3.3

RESEARCH QUALITY ASSURANCE

3.4

RESULTS

4.

MAINTENANCE LOGISTICS NETWORK

4.1