Design for Disassembly as a Method to Improve the

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KOMtech Technology Review 2013

Design for Disassembly as a Method to Improve the Sustainability of Offshore Accommodations

SHALLOW WATER TECHNOLOGY

ACKNOWLEDGEMENTS Financial support by the Research Council of Norway under grant no. 193326 (“Innovative foundation structure for offshore wind turbines”) is gratefully acknowledged. OWEC Tower AS acknowledges Professor Michael Muskulus and his team of the Offshore Wind Technology Group at the Department of Civil and Transport Engineering at the Norwegian University of Science and Technology (NTNU) for technical collaboration they have extended in past years.

AUTHOR’S CONTACT

[email protected]


REFERENCES [1]

M. Muskulus, S. Schafhirt, D. Zwick, S. Narasimhan and S. Nesheim, „RAVEN – Results report“, Technical Report WTG-R-0004. Offshore wind technology group, Department of Civil and Transport Engineering, NTNU, October 2012

[2]

M. Seidel, M. von Mutius, P. Rix and D. Steudel, „Integrated analysis of wind and wave loading for complex support structures of offshore wind turbines“, Proceedings Offshore Wind Conference, Copenhagen, 2005

[3]

C. Böker “Load simulation and local dynamics of support structures for offshore wind turbines”, Hannover: InstitutfürStahlbau, Gottfried Wilhelm Leibniz Universität Hannover)

[4]

M. Seidel, F. Ostermann, A P W M Curvers, M. Kühn, D. Kaufer and C. Böker, „Validation of offshore load simulations using measurement data from the DOWNVInD project, Proc. European Offshore Wind 2009 (Stockholm)

[5]

J. Jonkman, S. Butterfield, W. Musial and G. Scott “Definition of a 5-MW reference wind turbine for offshore system development”, Technical Report NREL/ TP-500-38060 (Golden: National Renewable Energy Laboratory)

[6]

S. Schafhirt, D. Zwick, M. Muskulus, S. Narasimhan, J. Mechineau and Y. Salman „RAVEN – Modeling and analysis methodologies for complex support structures“, Technical Report WTG-R-0001. Offshore wind technology group, Department of Civil and Transport Engineering, NTNU, October 2012

!" Rick C. FIKKERT, MSc, University of Twente, The Netherlands Mariano E. OTHEGUY, PhD, MSc (KOMtech Europe) Elma DURMISEVIC, PhD, MSc, University of Twente, The Netherlands

THIS PAPER INVESTIGATES THE APPLICATION OF DESIGN FOR DISASSEMBLY ON OFFSHORE ACCOMMODATIONS, focusing on their sustainability. Current offshore accommodations typically feature mission-tailored designs that however do not allow for re-configuration without the intensive use of energy, materials, time and money. The changing demands of mobile offshore units and the ever-changing national standards on offshore accommodation could be effectively addressed with enhanced modularity and interior space flexibility. These aspects can be largely improved by applying Design for Disassembly (DfD), which has already introduced many benefits in other industrial sectors and has the potential to significantly improve several practical and environmental aspects of offshore accommodations. Comparison of a state-of-the-art design and a re-designed accommodation according to the DfD principles shows that its environmental impact can be notably reduced, affecting the impacts of the platform by its proportion in weight with respect to that of the platform. At the same time DfD accommodations are more flexible and easier to install and to remove. Furthermore the design aims at considerable re-use of load-bearing structure, increasing the revenue per unit weight of virgin materials used and reducing the end-of-life costs.

No part of the materials published in this journal may be reproduced, stored in a retrieval system or transmitted in any form whatsoever without the prior written permission of KOMtech

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INTRODUCTION

THEORETICAL FRAMEWORK

Challenges for sustainability

Sustainability

The oil and gas sector has a 100-year history in the offshore industry with notable achievements but also unavoidable associated risks and pollution of the sea and the atmosphere. While the dependency on oil and gas is greater than ever, the public preference for sustainable solutions is growing[1]. However, while energy solutions are progressing to harness the wind, wave and tidal energy, the offshore platform technology has remained largely the same.

The term sustainability is not new. It has been used since the early seventies and has had a plethora of meanings since then. The most widely used definition is that of the World Commission on Development and Environment, led by Mrs. Gro Harlem Brundtland[4]: “Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs”. This definition does not impose a certain method or direction and many methods have tried to define a way to reach sustainability. Some methods, such as the ‘sustainable emissions and resource usage method’[5], focus on limiting emissions and the use of natural resources. Other methods add social concerns to the definition of sustainability. Some authors suggest that not all social concerns are connected to sustainability, but many nonetheless agree that taking natural (planet), social (people) and financial (profit) benefits into account is needed[6] (Figure 1). This is the sustainability principle that is followed in this work.

Some materials used in these platforms are becoming scarce and the general costs of materials are rising. These factors give an incentive to look at innovative solutions for the material and energy demands of platforms[2]. Research goals

The goal of this research is to investigate the theoretical and practical aspects of applying ‘Design for Disassembly’ to offshore platforms. The main research question is therefore: “Is Design for Disassembly an appropriate method to improve the sustainability of Offshore Accommodation Units and how can it be applied?”[3]

฀

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฀ ฀ and sustainability

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STUFF SPACE PLAN

SKIN STRUCTURE

assembly times[13], assembly costs[8] and has a lower number of associated on-site errors[12]. During the use phase of the products the benefits include easy upgrading[14, 15] and flexibility in spatial layouts[12]. Ease of repair and maintenance furthermore improves quality and saves costs by saving materials[12, 8]. Ease of upgrade, repair and maintenance also means that aesthetic preferences are easier to meet and that the service life of the building can be extended[16,8, 26]. As parts, components and systems are nondestructively removed, they can be reused in the same or in other buildings[15, 16, 8]. Reuse of components reduces resource use[15, 12, 18], preserves the energy embodied in the materials[16, 12, 19] and keeps its embodied value in circulation[41].

SITE

Figure 2. Layers of change in buildings, from[9]

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Figure 3 summarises the benefits in a visual scheme to provide overview how the benefits link to the triple bottom line[6] categories.

DfD and sustainability

฀ ฀ ฀ ฀ ฀ Accommodation Modules, including the impacts on the environment Figure 1. Visual representation of the triple bottom line of sustainability: people, planet and profit[7]

฀ ฀ ฀ ฀ ฀ Disassembly solutions in the design of offshore accommodations ฀ ฀ ฀ ฀ the environment ฀ ฀

in other industries it is relatively new. In the early 1990s, for example, waste of consumer products posed considerable problems and as a result the use of DfD grew significantly[8]. Besides that, the changing requirement in the built environment also results in a call for more flexible products. Brand[9] argued that buildings have six levels that ought to change independently from one to another (Figure 2).

SERVICES

Several aspects need to be investigated to answer this question: ฀

The changing demands of mobile offshore units and the ever-changing national standards on offshore accommodation could be effectively addressed with enhanced modularity and interior space flexibility.

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Brand[9] promoted transformable buildings because he saw that the use of conventional buildings changes over time and that adaptation currently costs large amounts of material and energy and generates large amounts of waste. But better use of limited resources[10] and reduction of waste[11] are not the only benefits.

Design for Disassembly

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Once these aspects are combined, the conclusion on the feasibility of the Design for Disassembly can be drawn.

One way to achieve the benefits of sustainability is the use of Design for Disassembly (DfD). This method aims to take the disassembly of products into account from the very first stages of the design. Design for Disassembly is not a new method and is already used in several areas for some time. The automotive and computer industry are two examples where it is already used for several decades. However,

There are many benefits to DfD, not only for the planet, but also for the people and profit dimensions of sustainability. Benefits from disassembly include shorter disassembly times[12, 13], lower disassembly costs[12, 8] and lower impacts on the direct environment[12]. Easier disassembly in many cases also means a simplification of products[8], which has benefits for

Regulatory framework

The mobile nature of offshore platforms means that they are subjected to changing rules and regulations. Besides the international rules[20-22], each country has its own set of rules to safeguard over people and environment[23-33]. These rules stipulate for instance different sizes for the cabins, different sizes for the recreation room and different layouts. Current accommodations do not take these changing rules into account and use the peak occupancy and the most stringent applicable regulations for the design. This means that the accommodations are over-dimensioned for, sometimes, a very significant part of their lifetime.

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Embrodied energy not wasted

Design domains

Reuse of the components possible Easier disassembly

Reuse potential used Less resourse use

Less incineration

Hierarchy

Less waste

Easier replacement of systems

Technical

Lower waste costs

More up-to-date systems

Less energy use

Less dust and noise from machines

Less destruction of capital

Spatial requirement users met Higher flexibility

Functional independence Systemisation

Functional Planet

Less emissions

Less materials used Easier upgrading/ repair/maintenance

Profit

Less impact

Aesthetic preferences easier met

Physical

Less materials required Shorter assembly times

Quicker disassembly

Shorter disassembly y ttimes

Life cycle coordination

Assembly sequences Type of connection

Higher comfort Less vacancy Lower assembly costs

Less errors on site

Higher safety

Less ‘time-to-market’

Cost saving

DfD Methodology

of higher order, minimising the dependencies amongst components.

Design for Disassembly has to be taken into account from the start of the design process to maximise the possible benefits. Systems, components and parts need to be independent from each other and have to be exchangeable to enable easy disassembly.

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These criteria (independence and exchangeability) are therefore the main performance criteria of the transformation capacity. To reach this in the functional, technical and physical domain there are eight aspects that need to be looked at[34] (Figure 4):

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Groups of functions should be clustered in systems. ฀

Components and parts that are changed more often should be lower in hierarchy than more fixed ones. For example the load bearing structure should be high in the hierarchy. ฀

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One element acts as an intermediary between the parts in a component and other components

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Mobile Self-installing Platforms (SiPs) with tabletop design (Figure 5) are selected for the case study, because: ฀

฀ ฀ ฀ ฀ ฀ ฀ SiPs are subjected to changing rules and therefore to changing room requirements

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฀ ฀ ฀ ฀ ฀ ฀ ฀ ฀ and makes a change of accommodation modules possible

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Coordination between material and functional life cycles ensures correct specification of hierarchy, assembly sequences, etc., so that components can be disassembled and replaced when it is needed. ฀

Parallel assembly sequences ensure independent change of components. ฀

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Dismountable connections allow for disassembly without disturbing other parts.

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Different functions of components and systems should be independently changeable.

CASE STUDY Case study selection

Figure 3. Network of benefits of applying Design for Disassembly[3]

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Figure 4. Relation of DfD aspects to design domains modified from[34]

Lower labour costs

Lower life cycle costs

Easier assembly

People

฀

An open geometry allows for independent removal of assemblies. There is a strong resemblance between the built environment and the accommodation blocks installed in offshore platforms. The way they are currently constructed, the scale and the purpose are generally similar. It is therefore expected that the benefits of DfD in the on-shore built environment can also be obtained by designing offshore accommodations according to the principles above.

One of the design choices of SiPs is that they do not use external cranes or barges for their installation. Reducing the need for external cranes for in-situ maintenance, upgrade, downsize, etc., of the accommodations could therefore be beneficial.

Base element’ specification

Geometry

Market demands easier met Quicker assembly

Aspects of Disassembly

Less ‘downcycling’ of materials

Less resources neeeded More recyling ecy g

Easier separation of materials

Performance criteria

Exchangeability


Independence

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Figure 5. 3D Model of Sip with table-top design, from[35]

CURRENT ENVIRONMENTAL IMPACTS The environmental impacts of the current case are investigated on the following in order to establish aspects suitable for improvement. This analysis is later used to assess this improvement by comparing with the impacts of the re-designed accommodations in the context of the whole platform. The impacts were investigated with the Life Cycle Analysis (LCA) method “ReCiPe”[36] which describes the impact on the environment with 18 categories. The functional unit for the analysis was taken as “Provide a safe living area in an offshore environment for 100 people for 1 year”. The LCA calculation was based on a welldocumented case of jackup-type platform incorporating representative accommodation upgrade works, and adapted to the particulars of Self-installing platforms according to the functional unit chosen. The modelled fabrication, maintenance and end-of-life of the platform included the embodied energy and impacts related to the metallic materials of the platform, modelled as steel. The energy use during the use phase and the maintenance works corresponds to the accommodations only. The results show that the main source of environmental impacts is the fabrication of steel structures, followed by the consumption of fuel used for energy. These impact sources and the main causes of the energy demands are listed in table 1. Focusing on the production phase, the categories where the current platform has the highest normalised impacts (ratio between the characterised or absolute impacts and a common reference value, which enables comparison amongst impacts) are human, freshwater and marine ecotoxicity, freshwater eutrophication and metal depletion (Figure 6). The impacts also include climate change, however the normalised value of this impact was 9 times lower than the next impact in relevance, freshwater eutrophication.

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Within this phase, the impact of the production of the accommodations is comparable to its proportion in weight, about 5%.

Causes of impacts and energy demands of accommodations

Impact

Cause

Climate change

Steel and slags for steel

Human toxicity

Steel production

Metal depletion

Steel for walls

Fossil depletion

Fuel for offshore generators and transport

Marine ecotoxicity

Metal working

Freshwater ecotoxicity

Metal working

Energy: Production

Offshore generators for heating and electricity

Current disassembly limitations

Energy: Maintenance

Producing paint and coatings

Energy: Recycling

Transport of scrap metal

The current design of the accommodation modules was investigated by examining several accommodation blocks and stationed offshore units at the Keppel Verolme Shipyard. These accommodations scored consistently low on the disassembly aspects mentioned in the DfD methodology.

6.00E+03 20000

฀ ฀ implemented

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฀ ฀ ฀ to become more parallel

฀ Production 4.87E+06, 18%

Transport, 4.99E+05, 2%

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Use, 2.03E+07, 74%

Load bearing

Enclosing

2

14000 4.00E+03 12000 10000 3.00E+03

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Servicing 32

Figure 7. Life cycle energy demands per life cycle phase of a SiP, in MJ, averaged for the chosen functional unit

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13 14

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5

17 31

7

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12

20

19

18

21 8

Particularly, the functional dependencies between different components were numerous (Figure 8) and their assembly was not found to be parallel but sequential (Figure 9). Further investigation of the modules revealed amongst others unclear hierarchy, direct and irreversible connections and closed geometries.

29

16

28

25

27

26

15

9

23

30

24

11

Figure 8. Functional dependencies amongst componets in the existing accommodations

Components

1

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step 1 step 2 step 3 step 4 step 5 step 6

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2.00E+0.3 1.00E+03

฀ ฀ ฀ ฀ ฀ ฀ ฀ of environmental impacts

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Figure 9. Assembly sequence of currently existing permanent accommodations

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step n

et de et

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ec e in M

ar

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pl

ox ot

ot er at hw

Fr es

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ity ic

ic ox

at ic ph tro eu er

at hw

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n io

ty ci xi to an um H Fr es

ity

0.00E+00

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Figure 6. The most relevant normalised impacts from the production phase of a SiP as per the chosen functional unit

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Partitioning

1

3

The causes for the current environmental impacts and the causes of the limited disassemblability of current offshore accommodations give the following input for the application of DfD in order to improve the sustainability of the platform:

Accommodations

97

Accommodations

Aspects for the redesign

Full platform

18000 5.00E+03 16000

impacts, points

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10

As shown in Figure 6, the accommodations account for a significant part of the overall impacts of the platform. This, together with their resemblance with on-shore buildings, makes the accommodation block are a good starting point for the application of Design for Disassembly in offshore platforms.

Energy used by transport vehicles

Energy: Use

Maintenance, 9.96E+03, 0%

From the findings above it was decided to focus the new design into the re-use of load bearing structure, so that the impacts associated with the fabrication and recycling of metallic parts are minimised.

Steel manufacturing

Energy: Transport

Disposal, 1.64E+06, 6%

Besides the impacts of the platform, the energy demands per life cycle phase were studied. As Figure 7 shows, most of the life cycle energy is used during the use of the platform, while the fabrication and end-of-life recycling of the platform also contribute to a large energy demand.

ec

Table 1.




Normalised environmental impacts, points Normalised environmental

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The associated impacts embodied in the materials are higher than those derived from the use of diesel for energy production and consumption.

n

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SYSTEM DESIGN Design requirements

Four probable scenarios were taken for the development of the new accommodations. The transition from one scenario to another reveals the parts that remain the same and the parts that need to be flexible. The four scenarios are: 1) Minimum oil and gas facility platform, unmanned, accommodations on host platform, 0 people[37] 2) Minimum oil and gas facility platform, manned, accommodations on Self-installing Platform, 12 people[37] 3) Offshore wind farm self-installing temporary or permanent substation/maintenance facilities for medium-size wind farm, maintenance of 80 wind turbines and electrical substation, 32 people[38] 4) Offshore wind farm self-installing temporary or permanent substation/maintenance facilities for large wind farm, maintenance of 175 wind turbines and the substation, 70 people[39]

The units are protected from the weather with walls that connect to the outside of the modules (Figure 13). The inside partitioning of the modules is done with connectors in the floor and ceiling and wall panels. This system creates a raised floor and a lowered ceiling, both housing the services (Figure 14). The services are connected with demountable connections (Figure 15) to the hallways (Figure 16), maximising the connection and disconnection flexibility. The hallway acts as a central installation area where the services of other rooms connect and are subsequently connected vertically through the staircase modules (Figure 17).

Figure 12 Detail of the module corner connection

Figure 15. Demountable connections currently being used in on-shore buildings

Figure 13. Outside wall of a module

Figure 16. Services connect to the hallway

Figure 14. Cross-section of the designed system for flooring, walls and ceiling

Figure 17. Central services of the accommodations running along the hallways connect vertically through a column of staircase modules

This design was found to be highly innovative and as such has been the subject of a provisional patent application (Singapore Patent Application No. 201209014-8).

Other requirements for the accommodation design included safety regulations, the inside environment, choice of materials, spatial requirements over time, functional requirements of the different rooms and demands per life cycle phase, including transport and commissioning. System design

The modules are designed on the basis of the requirement of the four scenarios and the adaptation to the English[24-26], Danish[27-29], and Norwegian [30-33] rules. The most suitable module size was found to be 4m by 6m where the transverse walls can be moved in steps of 50cm to create flexible spaces. The longitudinal walls are also designed for re-location, increasing the interior flexibility. Spaces larger than one module are also possible due to the absence of load-bearing internal walls (Figure 10).

Figure 10. 3D model of the proposed design (transparency to show internal module)

The modules connect to one another on the corners with bolted connections, forming a strong and rigid assembly (Figures 11 and 12). These connections are designed to have the least possible openings to the inside. The corners are therefore connected from the outside (Figure 12), allowing module removal or installation without disturbing the adjacent modules.

Figure 11. Modules connect to each other on the corners

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RESULTS Environmental impacts of the new design

The new design was compared to the current case to determine the difference in environmental impacts. In this LCA the same method “ReCiPe”[36] was used with the same functional unit and the same supporting structure, where the accommodations designed for disassembly were assumed to be reused after the service life of 20 years. The assumptions about energy demands during the use phase were kept the same. The impacts of the redesigned accommodations were found to be noticeably lower than the impacts of the current design, in the context of the whole platform. This is coherent with what shown in Table 1 above, where the fabrication with steel and diesel fuel use are identified as the main sources of environmental impacts. Hence, the massive reduction of the environmental impacts and the embodied energy that are associated with the reuse of materials, is affected by the proportionality in weight with respect to the whole platform (see table 2). Table 2.

The reduction in environmental impacts in the life cycle phases is more substantial though, as shown in Table 3. Reduced maintenance derived from the enhanced interior and module flexibility, as well as the naturally advantageous reuse strategy for the end-of-life both show up as notably reduced normalised environmental impacts scores. The LCA also shows that most of the impacts associated with offshore platforms and accommodations as modelled in this work come from the fabrication with steel and the use of energy produced by the combustion of diesel. The energy usage during operation is still higher than the energy embodied in the structures and equipment along the service life of the platform. However, the associated impacts embodied in the materials are higher than those derived from the use of diesel for energy production and consumption (see Figure 18). This differs from the typical case in shipbuilding and shipping, where the much higher energy needed for propulsion makes the life cycle impacts of ships much

Reduction of environmental impact in the whole platform due to the redesign of the accommodations

Especially in platforms that are used for multiple operations in several areas, this ‘standard proof’ accommodation design could prove very useful. more dependent on their use phase[40]. This shows that in the offshore construction industry improvements in the embodied energy and impacts are as important as those in the energy use. Additional measures such as higher insulation values, heat recovery in ventilation and the use of renewable energy sources could reduce the impacts and energy demands associated with the use phase even further, making the energy and impacts embodied in the materials even more relevant.

New accommodation design

Change

Added functionality

Human toxicity (points)

10259

9607

-6.35%

Freshwater eutrophication (points)

2161

2038

-5.71%

Freshwater ecotoxicity (points)

6401

6035

-5.73%

The functionality of the accommodations is also assessed in the evaluation of the results. The accommodations reveal improvement on the DfD aspects. The assembly sequences for instance are more sequential (Figure 19) and the number of functional dependencies is decreased (Figure 20).

Marine ecotoxicity (points)

12316

11604

-5.78%

Metal depletion (points)

2325

2191

-5.77%

Total points (over 18 impact categories)

42045

39282

-6.57%

Table 3.

Reduction in normalised environmental impacts per life cycle phase, assumed that the production and use phases remains as in the current design

Production Transport

Current design

New design

Change

1.86E+04

1.86E+04

0.00%

2.89E+03

2.83E+03

-2.10%

Use

8.43E+03

8.43E+03

0.00%

Maintenance

2.10E+02

1.33E+02

-36.77%

End-of-Life

1.19E+04

9.27E+03

-22.06%

1

2

3

4

5

6

7

8

step 3 step 4 step n

Figure 19. Assembly sequence of the new modules

Accommodations Load bearing 1 3

Enclosing

2 Servicing

4 6

7

Partitioning

8

9 12

15 10

11

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14

17 16

16000 14000 Production

8000 6000

21 19 18

Figure 20. Functional dependencies in the new a ccommodations

18000

10000

10

step 2

20000

12000

9

step 1

5

Current accommodation design

Impact on the whole platform: impact categories

Components

In the case of the use of SiPs in Offshore Wind Farms, for instance as electrical substations, the energy used in the accommodation will be 100% renewable. Hence, all the environmental impacts related to the diesel-derived energy will disappear, leaving mostly the energy and impacts embodied in the materials.

Normalised environmental impacts, points

100

Transport Use Maintenance Recycling

4000 2000 0

Figure 18. Total life cycle normalised environmental impacts of the SiP per life cycle phase (current design)

20

101

102


The use of indirect demountable connections and clear systemisation furthermore improves the accommodations. These are now flexible, easy to upgrade, easy to maintain and easy to disassemble. Especially in platforms that are used for multiple operations in several areas, this ‘standard proof ’ accommodation design could prove very useful. Life Cycle Costs

The costs over the life cycle are an important factor in the success of the new design. A basic qualitative analysis shows that: ฀

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฀ ฀ ฀ ฀ ฀ ฀ ฀ ฀ ฀ many types of offshore platforms and possibly also for certain applications onshore. ฀ ฀ ฀ ฀ ฀ ฀ ฀ standardised design and would reduce the production costs ฀ ฀ ฀ ฀ ฀ ฀ ฀ ฀ ceilings and services, the costly time to update the accommodations could be reduced significantly. This save man-hours and could in some cases save docking time. ฀ ฀ ฀ ฀ ฀ ฀ ฀ end-of-life reduces the costs involved in transport and may also reduce the costs of scrapping. ฀ ฀ ฀ ฀ ฀ ฀ ฀ wasted at the end of the first life cycle. With increasing prices for materials the end-of life value of the modules can still be high and this value can keep on producing revenue instead of being largely lost through scrapping. ฀ ฀ ฀ ฀ ฀ ฀ ฀ ฀ stackable to up to four decks. This initially introduces redundancy in load bearing capacity because all modules must be able to support three more decks on top. The resulting weight of the structure may reduce the payload of the

platform in comparison with conventional accommodation. One possible solution for this issue is the fabrication with materials lighter than steel. The possible increase in construction cost would be however distributed along a longer service life, which could level it off with that of current designs. The end-of-life costs could thus be potentially lower. An estimation on the total life cycle costs could be addressed when more information is available on the aspects mentioned above. CONCLUSION A method to apply DfD to accommodation modules has been developed and used in the design of accommodation modules featuring very high flexibility both in internal spaces and module configuration. This design allows a very convenient flexibility, enabling virtual standard-proof compliance and high ergonomics, as well as the long-lasting reuse of its metallic load-bearing structure. LCA calculations showed that steel construction is the largest source of embodied energy and associated environmental impacts during the production and end-of-life recycling phases of the life cycle. While the use phase energy is higher than that embodied in the materials, the impacts embodied in these were shown to be more significant than those derived from diesel-produced energy. As a result, a reduction in the environmental impacts of the platform is observed, which is approximately proportional to the weight ratio “accommodations/ platform”, showing that DfD is an appropriate method to increase the sustainability of offshore platforms. The flexibility of the platform makes it ‘standard proof ’ and easy to assemble and disassemble. The costs of the systems are yet unknown, but are expected to be lower in some cases as shown in the literature. Taking additional measures, e.g. energy-saving equipment, can furthermore reduce the impacts of the accommodation even further.

ACKNOWLEDGEMENTS The research presented in this paper is the result of a close collaboration between Keppel Offshore & Marine Technology Centre Europe and the University of Twente in the Netherlands. The authors would like to thank all the people involved for their support.

AUTHOR’S CONTACT

[email protected]

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Bloemen. (2010). Design for Disassembly of Facades. Delft University of Technology, Delft.

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Westkämper, E., Alting, & Arndt. (2000). Life Cycle Management and Assessment: Approaches and Visions Towards Sustainable Manufacturing (keynote paper). CIRP Annals - Manufacturing Technology, 49(2), 501-526.

[19]

Dimoudi, A., & Tompa, C. (2008). Energy and environmental indicators related to construction of office buildings. Resources, Conservation and Recycling, 53(1-2), 86-95.

[20]

International Labour Organisation (1949). C92 Accommodation of Crews Convention (Revised). Paper presented at the General Conference of the International Labour Organisation, Geneva.

[21]

Organisation, I. L. (1970, 30th October 1970). C133 Accommodation of Crews (Supplementary Provisions) Convention. Paper presented at the General Conference of the International Labour Organisation, Geneva.

[22]

International Maritime Organization (2004). International Convention of Safety of Life at Sea. London.

[23]

American Bureau of Shipping (2002). Guide for Crew Habitability on Offshore Installations. Houston.

[24]

UK Health and Safety Executive (1996). Guidance for Inspectors on Offshore Installations and Wells.

[25]

UK Health and Safety Executive (2001). HSE OTO REP 01 068: Noise and vibration. London.

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UK Health and Safety Executive (2011). HSE OTO REP 01 069: Deck, stairways, gangways and their associated handrails. London.

[27]

The Danish Energy Authority (1992). DEA Executive Order No. 579 of 23 June 1992. Copenhagen: Danish Ministry for Environment and Energy.

[28]

The Danish Energy Authority (2006). DEA Executive Order No. 54 of 31 January 2006. Copenhagen: Danish Ministry for Environment and Energy.

[29]

The Danish Energy Authority (2008). DEA Executive Order no 396 of May 15 2008. Copenhagen: Danish Ministry for Environment and Energy.

[30]

Det Norske Veritas (2008). DNV-OS-D301 Fire protection. Høvik.

[31]

Det Norske Veritas (2009). DNV-OS-J201 Offshore Substations or Wind Farms. Høvik.

[32]

Det Norske Veritas, (2011). DNV-OS-A101 Safety Principles and Arrangements. Høvik.

[33]

Standards Norway (2006). NORSOK C-001: Living Quarters Area. Lysaker.

[34]

Durmisevic, E. (2006). Transformable Building Structures

[35]

Keppel Verolme BV. (2011). Design Document Self-Installing Platform. Rotterdam: Keppel Verolme BV.

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Goedkoop, M., Heijungs, R., Huijbregts, M., Schryver, A. D., Struijs, J., & Zelm, R. v. (2009). ReCiPe 2008. A life cycle impact assessment method which comprises harmonised category indicators at the midpoint and the endpoint level.

[37]

Perenco UK (2012). Trent and Tyne. Retrieved 14th August 2012, from http://www.perenco.com/operations/united-kingdom/trent-and-tyne.html

[38]

Keppel Verolme BV. (2010). Global Tech 1. Retrieved 14th August 2012, from http://www.keppelverolme.nl/global-tech/

[39]

London Array Limited (2012). Harnessing the power of offshore wind. Retrieved 14th August 2012, from http://www.londonarray.com/

[40]

K. Takeshi, K. Michihiro, H. Katsuhide, S. Tetsuya, N. Takeshi, S. Hideyuki, S. Akio & F. Maasaki (2002). Study for the application of LCA to Ship. Papers of National Maritime Research Institute.

[41]

Otheguy, M and Panagiotidou, E, “Towards a circular economy: increasing value circulation and reducing environmental impact”. Technology Review 2013, Keppel Offshore & Marine Technology Centre, Singapore.

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Towards A Circular Economy: Increasing Value Circulation and Reducing Environmental Impact


Towards A Circular Economy: Increasing Value Circulation and Reducing Environmental Impact !"Mariano E. OTHEGUY, PhD, MsC (KOMtech Europe) Eliza PANAGIOTIDOU, MSc Student (Technical University Delft)

IN THE CONTEXT OF AN UNSUSTAINABLE SITUATION OF ECOSYSTEM DECLINE AND MATERIAL SCARCITY ACKNOWLEDGED WORLDWIDE, a transition towards a circular economy is seen as a possible vehicle towards a sustainable economy and society. Within this framework, equipment remanufacturing stands out as a useful tool to steer our current linear production systems into circular, more sustainable ones. This paper presents and discusses recent findings on sizeable business opportunities that can improve on people, planet and profit, current trends in coming environmental legislation and the particularities of offshore platforms. The discussion and results suggest that the current linear ship and platform fabrication systems can be notably improved by incorporating equipment remanufacturing with a simultaneous double improvement in increased wealth generation per kg of raw material and noticeable reduction in environmental impacts.


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INTRODUCTION The first decade of 21st Century has been characterised by an increasing environmental awareness, in particular regarding the increasing scarcity of key natural resources, the on-going destruction of the natural environment and consequently that of the natural services that support all our activities and the phenomenon of global climate change. The technological developments achieved since the Industrial Revolution, naturally following the cultural and economic context of the era, have largely led to an emerging resource depletion and environmental destruction that only recently has been acknowledged, widely disseminated and started to be addressed.

wind turbine manufacturing using rare earth permanent magnets). Shipbuilding and offshore construction rely heavily on steel supply which has been historically subjected to significant market fluctuations and which demand is expected to raise 80% in the next 20 years[3]. Also, the synthesis nature of the offshore construction business makes it dependent on a network of suppliers who do need a varied range of materials to manufacture the engines, pumps, cabling, piping, dedicated machinery and IT and control electronic systems needed in ships and platforms, increasing the dependency and risk of the industry with regard to raw material scarcity.

The resulting “end-of-pipe” designs, technologies and processes are typically designed for supply, fabrication, assembly and use but to a lesser extent for maintenance and rarely for any of the inevitable subsequent life cycle phases (namely decommissioning, removal, reverse logistics and possible reuse, remanufacturing, recycling, disposal, etc.). Such designs lead intrinsically to situations where the value put into the product is difficult to be effectively recovered at its end-of-life, and where end-of-life units are scrapped and new ones are built following energy-intensive processes with a high environmental impact.

Additionally, the unsustainability of our current end-of-pipe production-consumption economic patterns also has the form of value loss because of short-lasting products ending up in landfills and waste-to-energy plants or being inefficiently thermo-mechanically recycled. As per 2012 an annual value loss of US$ 380-630 billion (~2-3% of the EU GDP) was estimated from a subset of European Union manufacturing sectors only[4]. This value loss could however be turned into an opportunity for material cost savings and thus increased profit by switching into circular product systems that enable more effective strategies to further profit from ever-circulating high value.

The currently on-going climate change, ecosystem decline and resource scarcity are already affecting the ability of businesses and communities to thrive and threatening their mid-term future possibilities. Particularly: ฀

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฀ ฀ ฀ ฀ ฀ ฀ of the natural services that enable all human economy and life, e.g. healthy food, clean water, clean air, water storage, flood protection, fertile soil, extreme weather buffering and many other[1]. The cost of this deterioration amounts for approximately 41 cents per dollar business revenue, averaged from 800 companies active in 11 economic sectors in 2010 as reported by KPMG consultants[2]. ฀ ฀ ฀ ฀ ฀ industries relying on certain materials (e.g.

CIRCULAR ECONOMY A circular economy is an economy system that is restorative and regenerative by intention and design, replacing the linear system “make-takedispose” with closing the loops of materials, using renewable energy and eliminating the use of toxic chemicals, aiming at eliminating waste through the redesign of materials, products, systems and business models. This approach, touching upon people, planet and profit, conceives the re-connection of production-usage-restoration cycles in two differentiated cycles of nutrients: the biological cycles (suitable for entering the biosphere) and the technical cycles (products to be used and returned to re-processing lines in an industrial cycle) as shown in Figure 1.

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Figure 1. Production-usage-restoration cycles in a circular economy (from[4])

LEGISLATION National administrations worldwide are starting to address a transition to a circular economy, with the objectives to further activate local economies and minimise the wasted value. Particularly in Europe and remarkably in the Netherlands (where the government has stated its formal commitment towards a circular economy and a sustainable management of natural resources[5]), the Roadmap to a Resource Efficient Europe issued in 2011 by the European Commission[6] acknowledges the issue of rising prices, the increasing scarcity of raw materials and their impact in the competitiveness of European businesses, as well as the value lost in landfills and waste-to-energy plants. The Roadmap outlines objectives to be met by 2020 and a policy framework aimed at rewarding innovation and resource efficiency, creating economic opportunities and improving security of supply through product redesign, greater reuse and savings in resources amongst others.

The policy trends outlined in the Roadmap expressly include: ฀

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฀ ฀ ฀ Continuation of the on-going process of product labelling with regard to energy and environmental performance, currently including an increasing number of consumer products like light bulbs, white goods, TV sets and light vehicles. ฀

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฀ EPR is a strategy designed to re-connect the environmental costs associated with products throughout their life cycles with their producer. This is currently enforced to manufacturers of white goods, electronics and notably passenger cars and light commercial vehicles, whose manufacturers are required to avoid

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The deterioration of natural services supporting our economies amounts for approximately 41 cents per dollar business revenue, as averaged from 800 companies active in 11 economic sectors in 2010. toxic materials, facilitate vehicle collection, appropriate de-pollution of fluids, part coding, ensure information for consumers and treatment organisations and ensure the reuse and recycling of minimum 85% and reuse and recovery (includes incineration) of 95% of the materials in weight by 2015[7]. ฀

฀ ฀ ฀ ฀ ฀ ฀ ฀ ฀ ฀ ฀ Emphasising the application of EPR strategies to shipbuilding.

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฀ ฀ ฀ ฀ ฀ ฀ Affecting offshore construction and shipbuilding because of their high metal-intensity.

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฀ ฀ ฀ ฀ ฀ ฀ One aspect of the current unsustainable paradigm embedded in societies and economies worldwide is the defective connection between their rules and the reality of the ecosystems that support them. For example, there is an increasing nature-inspired willingness to “do more with less” in the sense of increasing resource efficiency across industries and services, towards more employment and less use of natural resources. However, most of the tax systems in the world charge labour heavily while subsidises natural resources, a strategy directly opposed to the above. This problem can be addressed by shifting tax pressure from labour and the use of other renewable resources to the consumption of non-renewable materials and energy, making workforce cheaper and raw materials more expensive, aiming at steering industries and customers towards leaner processes and technologies.

Enforcing legislation towards a circular economy is thus gaining momentum, possibly affecting the shipbuilding sector in the mid-term. Additionally, strategies towards a circular system can be articulated

in order to generate immediate advantages, particularly on lower environmental impacts and higher circulation of value as detailed in the sections below. VALUE LOST IN THE OFFSHORE CONSTRUCTION SECTOR Some industries like the offshore construction industry are naturally prone to long product service lives. Offshore platforms are already widely repaired, maintained, converted and have their lives extended. These activities let the value embedded in their steel structures be effectively exploited for up to approximately 45 years before undergoing thermo-mechanical recycling, which is roughly 80% longer than their design lives. Particularly, the oil and gas industry in the North Sea has been providing Keppel Verolme with increasing repair, maintenance and conversion work since the late 70’s[8]. Such life extension practices are in fact partial remanufacturing processes in which the affected structures are thoroughly assessed, structural parts are (re-) designed to meet the new requirements, worn off parts are replaced and the entire platform is delivered and certified for operations for a certain period, often spanning beyond its original design life. In this way, the value embedded in the reused structures and systems keeps on generating wealth and avoid additional environmental impacts associated with the fabrication of new structures with virgin or recycled materials. However, the value embedded in the structures (structure design, metal microstructure, forming, cutting, welding, integration in large structures, coating, integration with systems, etc.) and chiefly in the systems (system and structural design, ergonomics, electrical parts, electronics, mechanical parts, integration in system networks, etc.) to be replaced/scrapped is largely lost. Figure 2 shows the materials value stream in the offshore construction industry. Existing

Figure 2. Materials value stream in the offshore construction industry and routes for product value recovery around Keppel Verolme

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value recovery routes comprise offshore conversion and life extension at Keppel Verolme and the use of recycled materials integrated in the raw material inflow as a standard industrial practice (e.g. recycled steel being part of the steel supplied to the yard). Next to these, a new route of highly efficient value recovery could be articulated in order to reuse the materials embedded in equipment to be discarded or replaced. This route is known as equipment remanufacturing. EQUIPMENT REMANUFACTURING Equipment remanufacturing is one suitable tool towards the integration of ships and platforms in the technical cycles of a circular economy system, enabling the reuse of large amounts of constructive materials. The process of remanufacturing typically implies the reception of the used piece of equipment or structure, its complete disassembly, the thorough cleaning of the parts, inspection and sorting of these, reconditioning or replacement of the parts which cannot be directly re-used, where upgrade is sometimes possible, reassembly and testing and verification. A remanufactured item typically offers the same or superior quality as an as-new product, and is to be differentiated from other restorative processes delivering lower quality outcomes such as [9]: ฀ ฀

฀ ฀ assemblies.

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remanufacturing is undertaken by independent operators. Environmental impact, environmental legislation, preventing competition in after-sales support and protecting intellectual property and brands also motivate, especially original equipment manufacturers, to remanufacture equipment. Third party remanufacturing also provides a means for supplying parts for products that have been phased-out, and in some cases may be a cheaper or faster source of parts than new replacements, for instance if products are replaced due to the technical obsolescence of some but not all of their components[10]. Automotive

Automotive parts have been remanufactured since the 40s, especially in the US where the Automotive Parts Remanufacturing Association conglomerates some 1000 companies worldwide which generate approximately US$ 10 billion yearly for commercial ground vehicles in the US only[11]. Copying machines

Xerox Corporation has been successfully remanufacturing its copying, printing and scanning machines for many years. Gradually incorporating design-for-remanufacturing features and trading with its copying machines through a lease programme, Xerox remanufactured some 1 million parts per year, reporting resource savings of US$ 200 million in 1991[12].

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฀฀ ฀ ฀ ฀ ฀ ฀ and/or satisfactory condition by surfacing, painting, machining, etc...

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฀ ฀ ฀ ฀ ฀ ฀ processing them into the same material or useful degraded material.

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฀฀ ฀ ฀ ฀ ฀ ฀฀ functional condition (whereas remanufacturing brings a system to a “like-new” condition).

Aircraft turbines

The manufacturer of aircraft turbines Pratt and Whitney showed that their remanufactured JT80 engine costed 40% less than a new one and that its performance had improved, reducing fuel consumption by 4%[13]. Rolls Royce has taken a step further in equipment remanufacturing by keeping its ownership. Using its TotalCare® service for civil aircraft, clients pay per engine flying hour, transferring maintenance cost risks back to the original equipment manufacturer and making reliability and running time a driver for profit for both the customer and the manufacturer[14].

Remanufacturing in other industrial sectors: economic and environmental advantages

Engines

Product remanufacturing is an established activity in several industrial sectors, where one motivation is business profit, especially where

Caterpillar Remanufacturing Services (Cat Reman), whose revenue has increased by 205% since 2001, currently remanufactures some 6,000 products

which amounted 73.000 tonnes in 2011. This includes their own equipment e.g. generator sets, engines, hydraulics, truck drivetrains, fuel systems, etc. as well as third party manufactured equipment e.g. components of Vestas wind turbines as announced in November 2011. Cat Reman states that their certified remanufactured equipment costs approximately 60 percent of the cost of buying a new machine and requires 50-60% less embedded energy by reusing 85-95% by weight of the materials from the original product[15]. The examples above show that equipment remanufacturing has serious potential to substantially reduce the environmental impact associated with the production of new products and keeps the value embedded in materials, structures and systems circulating and generating wealth. It also implies cost savings that can be passed on to the customer, giving an additional commercial advantage. Equipment remanufacturing in Self-installing Offshore Platforms

The Self-installing Platform (SiP) is a concept proven in the offshore energy sector, both for oil and gas (e.g. Trent Annex, delivered by Keppel Verolme in 2005 for production in the Trent and Tyne marginal gas field in the British sector of the North Sea, see Figure 3) and offshore wind (e.g. Global Tech I 400 MW Transformer Substation delivered by Keppel Verolme in 2013 to transform the energy produced by the offshore wind farm Global Tech I in the German sector of the North

Figure 4. Self-installing Substation for the Global Tech I 400MW offshore wind farm

Sea, see Figure 4). It incorporates temporary jacking mechanisms that enable cost-effective transportation to contract location and self-lowering the structural legs with no need of expensive and tight-scheduled floating cranes[16]. On the following, the possibility of an extensive application of equipment remanufacturing and its implications on environmental impact and value circulation are assessed on a case study SiP of 7,200 tonnes and accommodation for 32 persons, designed to be cost-effectively converted for multiple missions in the North Sea.

Figure 3. Trent Annex Self-installed Platform incorporating gas production topside facilities (left, next to support vessel)

LIFE CYCLE ENERGY USE A basic Life Cycle Assessment was performed on the case study SiP. Based on this calculation, Figure 5 shows an estimation of the total energy used and embodied in the structures and equipment, averaged per year during a 20 year platform life cycle.

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The LCA calculations show that the normalised impacts (i.e. impacts compared with a reference value, enabling comparison across different impact categories) of diesel-produced energy consumption do not affect only climate change (CO2 and other greenhouse emissions, see Figure 7). In fact, the normalised impact on climate change is lower than that on human toxicity, photochemical oxidant formation, particulate matter formation and fossil depletion. Figure 7 also confirms that the impacts of production (mainly driven by steel production and fabrication) exceed those of diesel-produced energy, in this case by a factor 2.

Figure 5. Life cycle energy usage distribution for the case study SiP (1-year equivalent, GJ)

Figure 6. Weight distribution in the case study SiP Figure 7. Normalised environmental impacts per life cycle phase of the case study SiP

Fossil depletion

Metal depletion

Water depletion

Natural land transformation

Urban land occupation

Agricultural land occupation

Marine ecotoxicity

Freshwater ecotoxicity

Terrestrial ecotoxicity

Marine eutrophication

Freshwater eutrophication

Terrestrial acidification

Ionising radiation

Use phase Production phase

Particulate matter formation

ENVIRONMENTAL IMPACTS The transportation industry, chiefly shipping, sees its environmental impact predominantly allocated to fuel production and consumption during the use phase of the ship, typically in terms of CO2-equivalent emissions[19][20]. However, offshore platforms require notably less energy needed for transportation during

Again, in case the SiP operates as a substation in an offshore wind farm, the energy consumed in the use phase is actually produced at the wind turbines. Such platforms do have diesel generators but these are operated only in the extreme case that all turbines are idling (e.g. because of extreme wind or very low wind) and the cable to shore fails. Because wind energy does not have climate change emissions, the environmental impacts typical of diesel consumption for energy production are reduced to zero. Even considering the lifecycle energy and impacts embodied in the turbines, these are notably less intensive than diesel generators in many categories of environmental impact, notably in fossil depletion, all sorts of toxicity and 300-400 times less intensive in climate change emissions [21].

their life cycle. Hence, it is expected that the impacts of offshore platforms are more evenly distributed amongst their different life cycle phases.

Climate change

As shown in Figure 5, both platform production and recycling accumulate 28% of the total energy

Equipment takes approximately 36% of the weight of the SiP, whereas the remaining two thirds are mostly steel structure and other metallic parts. Hence, and in view of a typical energy saving of 60% in the remanufacturing industry as stated above, the remanufacturing of equipment on board such a SiP could reduce by approximately 28%*36%*60% 6% of the total life cycle energy and all costs and environmental impacts associated with this energy. Interestingly, in case the SiP would operate as a substation in an offshore wind farm (e.g. the Substation Global Tech I, Figure 4), the energy consumed in the use phase would be renewable. In this case, assuming all the rest of the life cycle energy is non-renewable, the energy used for production and recycling would amount for 93% of the total non-renewable energy, where equipment remanufacturing could save up to 20%.

Even though more energy is consumed in the use phase than in the production and recycling phases, the environmental impact of offshore platforms lies very significantly or virtually only in the production phase, due to the fabrication of metallic structures and equipment.

Human toxicity

For simplicity a number of assumptions have been taken: since approximately two thirds of all materials in weight are structural steel and a large extent of the systems is also made of steel (see Figure 6), all these materials have been modelled as structural steel. This is conservative regarding the energy embodied in the manufacturing of equipment, as this has been shown to be in the order of threefold the energy embedded in structures[17][18]. Regarding energy consumption, the case study SiP is assumed to consume energy in the accommodation block only and is to be transported four times back and forth between Keppel Verolme and different locations in the North Sea for conversion works in order to accomplish four different missions during its service life of 20 years, after which it is scrapped and turned into recycled steel plates in Europe ready for further manufacturing.

used and embedded in the materials, a large percentage in comparison with the typical case in shipping and road transport, where the energy needed for propulsion power is still much larger than that embedded in the materials.

Photochemical oxidant formation

This calculation covers all the life cycle from the mining of iron ore and coal, steel making, rolling, forming, cutting, welding and integration into structures and systems, the transportation of the platform, the use phase, transportation and maintenance during service life and final transportation for scrap at its end-of-life, scrapping of structures and systems and fabrication of new material ready to be used in the construction of new parts.

Ozone depletion


Normalised environmental impacts, points

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From the above it becomes clear that even though more energy is consumed in the use phase than in the production and recycling phases, the environmental impact of offshore platforms lies very significantly or virtually only in the production phase, due to the fabrication of metallic structures and equipment. These processes impact the environment predominantly in metal depletion, freshwater eutrophication, climate change emissions and human, freshwater and marine ecotoxicity[22]. Hence, an increase in the reuse of metallic structures and equipment as that provided by remanufacturing has the potential to alleviate very significantly this environmental pressure.

value is calculated as the percentage ratio between the specific value as-new and the specific value as-scrap. Here, the specific value as-new is modelled as the purchase price of the item as paid by the yard or the owner divided by its weight in US$/tonne, while its equivalent as-scrap is modelled as the price paid by scrap yards by item category (transformers with copper winding, electric motors, scrap prices of merchant ships, etc.) as per December 2012.

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Figure 8 shows the value lost for platforms, systems and structures from the yard point of view. This

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฀ ฀ ฀ ฀ ฀ ฀ ฀ ฀ the highest price registered in 2012, while prices of scrap metals are thought to follow a longterm increase trend.

฀ ฀ ฀ ฀ ฀ ฀ ฀ ฀ ฀ transport the unit to a scrap yard, however this cost has been neglected.

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฀ ฀ ฀ investments, have been neglected.

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฀ ฀ ฀ ฀ ฀ ฀ ฀ avoid an underestimation of the scrap value and therefore an overestimation of the lost value.

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฀ ฀ ฀ ฀ ฀ ฀ centrifugal pumps have been assigned a scrap price corresponding to 100% stainless steel content, while the actual content is significantly lower.

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Additionally, it is acknowledged that second hand equipment (used, not remanufactured equipment) is often not delivering the specifications required per project and also not the quality and reliability required in the offshore energy market, hence often not the preferred route for the acquisition of equipment. Therefore it has been neglected, assuming that used equipment would be scrapped. As shown in Figure 8, between 90% and 99% of the value of structures and equipment typical of offshore units is lost in a scrap-and-recycle end-of-life scenario. Also, it can be seen that platforms integrating structures and systems have a specific value close to that of the structures, which is coherent with the large weight of these and the varied distribution of value in the equipment. This distribution follows a trend opposite to equipment size, having small pumps and generators more value per kg of material than their larger counterparts.

Figure 8. Platforms, structures and systems: specific value and value lost through thermo-mechanical recycling (scrapping)

Sanitary pump 150 W

Diesel Genset 400 kVA

Diesel Genset 1500 kVA

Transformer 155/33 kV 120 MVA

Water pump 37 kW

150m water depth

Jackup platform

Water pump 75 kW

400 MW SiP OWF Substation 40m water depth

100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

Carbon steel structures

Normalised specific value

An increase in the reuse of metallic structures and equipment as that provided by remanufacturing has the potential to alleviate very significantly the environmental pressure associated to their production.

The calculated lost value is regarded as conservative because:

VALUE LOST Beyond compliance with forthcoming legislation and the opportunity to remarkably reduce the environmental impact of platforms, remanufacturing could prevent a currently occurring massive loss of high end-of-life value.

Value lost through scrapping

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While conventional accounting of the residual value of engineered structures after the end of their design life is often set as close to zero, existing examples of remanufacturing in a range of industrial sectors as those above mentioned demonstrate that this does not necessarily reflect their actual potential. In particular the possibilities of additional wealth generation, especially for products designed to be remanufactured (with appropriate modularity, upgradeability and durability) could significantly increase their end-oflife value. In a recover-and-remanufacture scenario, a considerable part of this value could be kept in

circulation generating wealth for the builder and the owner, while retaining all the benefits of recycling vs steel making from ore (savings of energy, iron ore, coal, limestone, water, greenhouse gases, toxic emissions of mining and other associated industrial processes, etc.). EQUIPMENT REMANUFACTURE AROUND KEPPEL OFFSHORE AND MARINE Keppel Offshore and Marine, as systems and structures integrator, is in a position of advantage to enable and enhance a network of remanufacturers of equipment for offshore platforms, as well as to influence platform designs towards cost-effective equipment recovery, with the objective to offer platforms with a lower environmental impact and higher recoverable value that generate more wealth per kg of material used. As seen in other sectors, it is possible to construct a business model that reverts this additional wealth and value into remanufacturers, customers and the yard in terms of cost savings, lower environmental impact and compliance with coming legislation. While remanufacturers can benefit from delivering an as-new product at a fraction of the production cost of a new one, customers may cash savings in equipment cost and possibilities for cost-effective equipment upgrade or downsize. The yard can brand its enabling role in such network and offer a unique product with improved characteristics in people, planet and profit while also benefitting from associated cost savings. In turn, all stakeholders will benefit from the environmental advantages, legislation compliance and also from other direct benefits of remanufacturing such as reduction in waste and landfilled materials and disposal costs. Other indirect advantages are also worth mentioning, as the generation of skilled employment, increasing quality of life around transforming industrial areas[23] and lower supply risks in a changing world of scarce resources. Furthermore, the emerging two-direction

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relationship between yard, suppliers and customers has the potential to strengthen their commercial relationships and to work towards the optimisation of the whole platform value chain, instead of that of a single piece of equipment. The existing body of knowledge on equipment remanufacturing shows that certain characteristics are desirable for equipment to be suitable for effective remanufacturing (adapted from[23]): ฀

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Particularly, partnership with companies already expert in equipment remanufacturing can potentially deliver with consistency the required quality and the associated advantages in cost savings and environmental impact. ฀

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In-field assembled equipment tends to be difficult to cost-effectively remanufacture. ฀

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The product does not fail by total decomposition, but rather fails by not being able to provide its function while still keeping significant value and capabilities. ฀

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After one life cycle the product is still fit for purpose and it has not been made completely obsolete. ฀

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CHALLENGES The implementation of equipment remanufacturing in the offshore industry has a number of inherent challenges, e.g. ensuring that the remanufactured products have the required quality, the third party certification of remanufactured products and addressing the management of a possibly more complex contract structure. However, the currently expanding remanufacturing industry across a range of relevant sectors shows that it is possible to use it to improve our industrial systems in an advantageous way both regarding value and environment. BUSINESS MODELS As in the examples above, the trade, usage and ownership of the equipment suitable for remanufacturing is currently managed in a range of forms, where alternative business models may well be possible: ฀

฀ ฀ ฀ ฀ ฀ ฀ ฀ ฀ from repair and end-of-life goods without further payment to the owner. Remanufactured parts may have lower prices than new parts, or may not (automotive).

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฀ (Xerox).

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฀ ฀ ฀ ฀ ฀ ฀ ฀ all-inclusive performance hours (Rolls Royce).

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฀ ฀ ฀ ฀ ฀ ฀ ฀ exchanged by remanufactured products at a discounted price (Caterpillar).

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The core, i.e. the materials to be conserved and reused in the remanufactured product, must be recoverable at a cost significantly inferior to that of the new product. Insights on high recovery costs may be used to re-design structures and enclosures that facilitate disassembly and costeffective equipment recovery. The application of these criteria to the equipment on board a SiP results in a prioritised list of equipment suitable for remanufacturing. This list points primarily at large transformers, generator sets, electric motors, water and fire pumps, air compressors, HVAC equipment, lifting equipment, electric switchboards, winches, hydraulic and other equipment.

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CONCLUSIONS AND FUTURE WORK In an environmentally aware world, the transition towards a circular economy has been acknowledged as a vehicle towards a sustainable economy and society. Within this framework, equipment remanufacturing stands out as a useful tool to steer our current linear production systems into circular, more sustainable ones and capable to achieve savings in the order of 60% in embedded energy and 90% in reused materials. While the remanufacture of structures is common practice in the offshore industry (e.g. offshore conversion, life extension, etc.), equipment mostly

follows a linear life cycle where most of its value is lost through end-of-life thermo-mechanical recycling, intensive in energy and associated environmental impacts. It has been found that offshore platforms have considerable energy embedded in their materials, accounting for approximately 28% of their total life cycle energy use in the case of Self-installing Platforms. One third of the platforms in weight corresponds to equipment, thus its remanufacture alone could potentially reduce the overall energy use by approximately 6%. By contrast, LCA shows that the life cycle environmental impacts of these platforms are primarily linked to steel fabrication and secondly to fuel consumption during the use phase. Hence, developments towards the reuse of materials as equipment remanufacturing will have a major influence in the total environmental impact of offshore platforms. Remanufacturing has also the ability to keep value in circulation and increase many fold the amount of wealth generated per kg of raw material. Its application to on board equipment has thus the potential to notably increase the amount of value currently re-circulated by structures remanufacturing, because the value embedded in pieces of equipment is superior to that embedded in structures.

The insights above, related to SiPs but also applicable to other offshore units, are expected to become even more relevant in the near future, given the present trends in materials scarcity and environmental policy. The implementation of equipment remanufacturing in the offshore industry has a number of inherent challenges, e.g. ensuring that the remanufactured products have the required quality, the third party certification of remanufactured products and addressing the management of a possibly more complex contract structure. However, the currently expanding remanufacturing industry across the sectors shows that it is possible to improve our industrial systems, and that it is possible to profit both economically and environmentally from the fact that ”today’s goods are tomorrow’s resources at yesterday’s prices”[24]. There is an on-going effort at KOMtech Europe to further work in the possibility of a remanufacturers’ network around Keppel Verolme, using the prioritised equipment list above and exploring partnerships around equipment remanufacturing. This effort is aimed at seizing the opportunities and work on the challenges towards the benefit of customers, suppliers and the yard in all aspects of our activities: people, planet and profit.

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AUTHOR’S CONTACT

A Tool for Buckling Strength Screening and Assessment of Floating Offshore Structures


[email protected]

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A Tool for Buckling Strength Screening and Assessment of Floating Offshore Structures !" Vasil YORDANOV, M.Eng, B.Eng Plamen STOYKOV, Dipl. Eng

STRUCTURAL ELEMENTS SUBJECTED TO COMPRESSIVE LOAD may experience instability far before reaching their yielding strength. Offshore structures are exposed to continuously changing, external loads which combination may result in a severe structural failure. An important part of the design is the structural arrangement with respect to the buckling and collapse. Despite yielding and fatigue failures, the buckling failure strongly depends not only on the stress distribution but also on the geometrical and topological configuration as well. This paper focuses on the initial offshore structural design by providing a software solution which enables the buckling strength assessment in the early structural design stage. The tool is developed as a DNV – SESAM additional post-processor interacting mainly with Xtract module and some of the FEM files. The main emphasis is on the problems related with applying a buckling assessment algorithm on a simplified model of the actual structure, where the actual structural arrangement is not yet specified. The algorithms which were implemented follow the recommended practices of DNV and ABS for buckling and ultimate strength, thus these procedures are simple, reliable and sufficient for the evaluation of the buckling strength of the offshore structures. In addition, the proposed methodology gives information for different structural arrangements within a single study, which reduces the required time for structural design, increases the reliability of the designed structure and makes the optimization of the structural arrangement more easy and available.


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