Qualitative risks analysis on wave energy technologies

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20013

Examensarbete 30 hp Oktober 2020

Qualitative risks analysis on wave energy technologies

Nice Sam Bliss

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Teknisk- naturvetenskaplig fakultet UTH-enheten

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Ångströmlaboratoriet Lägerhyddsvägen 1 Hus 4, Plan 0

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Abstract

Qualitative risk analysis on wave energy technologies

Nice Sam Bliss

Wave energy as an industry is yet to emerge as a reliable energy technology. As of now, no wave energy device is said to be a

commercial success. Survival in the harsh ocean environment, the low frequency of waves and the variability of wave resources are the basic challenges that a wave power concept or a developer has to overcome. In addition to these challenges, there are number of other barriers such as economic and regulatory risks which hinder the development. A number of concepts or devices have failed one after another, to be commercially successful. Many of the failures were due to economic reasons and others were due to technical or environmental factors. Mistakes or failures can be repeated if they are not shared within the industry. This thesis attempts to identify the barriers to wave energy concepts and to analyze them qualitatively. Efforts have been taken to include the previous instances of failures and their causes so as to avoid them in future. The data was collected through literature review of published papers, reports, news articles and through a survey which was distributed among experts in the industry and academia. It can be seen that one barrier can trigger others and that they are interconnected. In the same way, solving one barrier can clear the others too. The risks faced by wave energy technologies are identified, analyzed and some mitigation methods are discussed.

ELEKTRO-MFE 20013 Examinator: Irina Temiz Ämnesgranskare: Jens Engström Handledare: Malin Göteman

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Popular Scientific Summary

During the oil crisis of 1970s, the world began to think about the alternative energy sources more rigorously. Renewable energy sources such as wind, solar and wave were the major sources among them. Today solar energy and wind energy have developed as mature energy sources whereas wave energy still lags behind, despite the higher energy density compared to the other two sources.

There have been many devices developed and tested, but only a very few of them have reached the full scale development or started commercial production, yet none of them could be considered as a success story. The reasons have been many, technical, environmental and economic. Many of the concept ceased to operate or develop further, due to lack of investments.

If one searches for reason of failure of a WEC concept, “failure to raise funds” can be identified behind many concepts or technologies. Difficulty in raising funds can be an outcome of various other factors. The thesis attempts to throw light on those factors.

The Literature review and survey response suggests that one cannot point a single reason or just economic factor to be causing the failures. In addition to technical, economical or environmental risks, regulatory and managerial factors also can contribute to the failure. Many factors are related to each other, one of those above factors can lead into another one. for example technical risks can induce economic difficulties. On the other hand, solving one barrier can solve another too.

External support from governmental and private agencies in terms of finance, consenting and resources can help the wave energy sector. A partnership or covenant between research, industry and authorities can be advantageous for the growth of the sector.

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Acknowledgements

First and foremost I thank God the almighty for helping me to complete the thesis and report.

I would like to express my sincere gratitude to my supervisor Malin G¨oteman for her help, patience, and idea while guiding me to finish the Master Thesis. I would like to thank Jens Engstr¨om as well for the support and attention along the project.

To my family, especially my wife, that always stand besides me and our parents who always support us.

Last but not least, to all of my colleagues in Uppsala, or overseas who always support me in the academic aspects and personal life. Thanks for all of the laughs, discussion, suggestions, and the experience that related to my study or not. Without them, I will not be a better person.

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Abbreviations

ABS - American Bureau of shipping CFD - Computational Fluid Dynamics DKK - Danish Kronor

DNV - Det Norske Veritas

EIA - Environmental Impact Assessment FEM - France Energies Marines

FiT - Feed in tariff

FMEA - Failure Modes Effects Analysis GL - Germanischer Lloyd

HAZID - Hazard Identification HAZOP - Hazard and Operability

OWC - Oscillating Water column

MRDF -Marine Research Development Fund (UK) MSP - Marine Spatial Planning

OREDA - Offshore and Onshore Reliability Data OTS - Over Topping systems

OWC - Oscillating Water column

OWSC -Oscillating Wave Surge Converter PTO - Power take Off

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List of Figures

2.1 Oscillating water column schematic . . . 12

2.2 Kvaerner WEC Toftestallen, Norway . . . 12

2.3 Overtopping WECs Wave dragon and TAPCHAN . . . 14

2.4 Pelamis wave energy converter . . . 14

2.5 Oyster wave energy converter . . . 15

2.6 Point absorber wave energy converter . . . 16

2.7 WaveBob wave energy converter . . . 17

2.8 WaveStar wave energy converter . . . 18

4.1 The response from survey: Risks faced. . . 24

4.2 Technical risks through phases, from results from survey. . . 24

4.3 Grid connection schematic diagram with charging regimes . . . 26

4.4 Probable effects of technical risks, results from survey. . . 27

4.5 Probable effects of technical risks on subsystems by development phase, results from survey. . . 28

4.6 Probable mitigation methods of technical risks, results from survey. . . 28

4.7 Economical risks through phases of development (from survey) . . . 30

4.8 Cost of WEC . . . 31

4.9 Probable effects of economic risks, results from survey. . . 34

4.10 Probable mitigation methods of economic risks, results from survey. . . 34

4.11 Legislative risks through phases (results from survey). . . 35

4.12 Environmental risks through phases, from survey. . . 39

4.13 Comparison of wave, wind and combined wave-wind production . . . 40

4.14 Biofouling on Oyster’s flap . . . 42

4.15 Probable effects of environmental risks, results from survey. . . 43

4.16 Mitigation methods of environmental risks, results from survey. . . 43 5.1 Rating of risks from survey response, numbers indicate percentage of respondents. 50

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List of Tables

3.1 Table of classification of risks . . . 21

4.1 Table of economical risks. . . 29

4.2 Table of environmental risks. . . 38

4.3 Some failures in wave energy. . . 46

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Chapter 1 Introduction

The world’s energy usage is increasing day by day. We have been relying on fossil fuels for our energy requirement in almost all aspects. But the sources of fossil fuels are running out and climate change or associated environment problems related to fossil fuels imply that it is the need of hour to switch to alternative sources or renewable energy resources. 169 countries have adopted renewable energy targets at the national/provincial level [1]. Wind, solar and hydro are considered as the main renewable sources of energy as they are freely available in nature.

Ocean energy makes up the lowest share among the energy production from renewable energy sources, even though wave energy has a higher energy density when compared to other renewable sources [1]. In other words, a large amount of energy is concentrated into smaller area, as an example one metre of Norwegian coast holds 400 times more energy than one sq.m of solar energy installations [2]. Even though the first patents for using wave energy techniques date back to 1799 [3], wave energy is still to emerge as a mature renewable energy source. Even though many devices or concepts have existed, many of them ceased to operate prematurely.

Capital costs and production costs are high for wave energy as of now. Development of a full scale prototype can cost about 70000-100,000 SEK per kW according to a British estimation, which can result in a cost of 500 million to 600 million SEK for a 10 MW device [4]. Since devices are being developed by small companies with single products they can’t invest much on their own and require support by considerable investments from authorities or companies.

As past results contains failures and unfulfilled promises, investors are reluctant to invest and it forms a vicious circle.

1.1 Challenges of wave energy development

The challenges or barriers of wave energy can be anything from technical, economic or even due to management issues, that hinders the growth of industry as a whole or for a single device. In the current situation, commercialization of a single device or technology can be considered as a big leap for the wave energy sector very few of the devices have been proved to be commercially successful. Certain factors such as variability of wave resources and storm conditions cannot be controlled beyond a certain limit, but others such as economical, regulatory and managerial issues can be addressed through a coordinated effort. Each barrier or risk is discussed in detail in the results chapter (Chapter 4). According to Clement et.al (2002), the fundamental or base challenges faced by wave energy technology can be summed up as [3]

• Wave energy characteristics vary widely ie, phase displacement and amplitude vary irreg- ularly. So it is nearly impossible to design a device that maximizes the efficiency in all ranges.

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Uppsala University 1.2. OBJECTIVE OF THESIS

• Coupling of slow and irregular motion of waves to the rotation of an electrical generator which can be at least 500 times faster.

• Survivability risks posed by hurricanes or storms.

• Uncertainty around the financial viability and regulations due to the lack of data or experience.

Apart from the technical challenges, economic challenges can hinder the development of wave energy. Attracting investment is not as easy as other mature technologies. Rising capital costs and uncertain maintenance costs would not be appealing either for any stakeholder or investor.

Another barrier that can hinder wave energy development is regulatory or legislative barrier.

The time for getting consent can extent up to years, depending upon the location, life, capacity of device.

1.2 Objective of thesis

The idea behind the thesis is to identify the risks within the wave energy industry, and categorize them according to types of risks, their severity and probability of occurrence. As of now one cannot find many studies on the barriers to wave energy except a few papers on non-technical barriers [5] [6]. The identification of barriers and sharing it is of utmost importance as it can help to avoid the repetition of mistakes. The rating or ranking of risks quantitatively is not possible at this point of time as enough data is not available or any of the devices has not worked enough time period to generate such data. Therefore this thesis takes a qualitative approach, using knowledge from experts in the field and data collected from the literature.

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Chapter 2 Wave energy technologies

Movement of wind across the ocean creates waves. The objective or principle of wave energy converters (hereafter referred as WEC) is to convert the energy of waves into electrical energy.

A large number of technologies or devices have been developed or proposed up to the date, and utilize various methods to drive the generator. Wave energy devices can be classified based on, either location of installation or technology used.

Based on location

WECs can be placed either onshore, near shore or offshore. The wave resources are higher in the offshore regimes and reduce closer to the shore. But easiness of maintenance and lesser risk in terms of survivability favors the near shore or onshore WECs. However, nearshore waters can also be risky for WEC devices as wave breaking force can damage the WEC devices [7].

Based on technology

Technologies used in WECs vary extensively. Some devices directly convert the wave motion into electricity using linear generators while some other devices collect the overtopping waves in a reservoir and use traditional hydropower technologies to convert the potential energy to electrical energy. In this chapter, main wave energy conversion techniques and some examples of each will be reviewed.

2.1 Oscillating water column

The oscillating water column is one of the first ever used WEC and considered as a relatively successful one. It consists of a fixed or floating concrete or steel chamber, partially submerged in the ocean. It uses the movement of air within a chamber where waves are trapped to drive the turbine/generator. Some OWC devices use Wells turbine which rotates in the same direction irrespective of the water flow direction. Except for the main rotor, Wells turbines have no rotating part, which makes them easy to maintain. The main advantage of OWCs is that all electrical parts can be installed outside the water, which reduces the requirement of survivability than that required in an ocean environment. For onshore OWC devices, maintenance activities would be easier and cost of transmission would be lesser than other wave energy concepts.

Another advantage is that since the OWC does not have any moving parts in water, very little effect can be expected on aquatic life. There are different types of OWC devices such as fixed structure (Kværner, Norway), breakwater Integrated (Mutriku, Spain) and floating structure (Mighty whale, Japan).

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Uppsala University 2.1. OSCILLATING WATER COLUMN

Figure 2.1: Oscillating water column schematic [8].

2.1.1 Kværner WEC

Kværner WEC is a multiresonant type WEC in Toftestallen, Norway constructed in 1985 [9].

As any OWC concept, the movement of waves creates the reciprocating motion of air and generated electricity. In the Kværner WEC, water was trapped by cliff walls of an island and the concrete extensions and harbour resonance ¹ takes place inside. The device operated for more than 3 years before getting destroyed in a severe winterstorm in 1988 [9].

Figure 2.2: Kvaerner WEC Toftestallen Norway, taken from [9] with permission from Elsevier.

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Uppsala University 2.2. OVER TOPPING SYSTEMS

plant consists of 16 turbines with the total power output of 296 kW. The Mutriku plant caters as a test rig for turbines and related auxiliaries before an open sea testing [11].

2.1.3 Mighty Whale

The Mighty Whale WEC falls under the floating OWC category of devices and was developed in Japan in 1998. It consisted of air chambers in which waves enter and the reciprocating motion of waves create pressure variation. The movement of the air column rotates a turbine and generates electricity. The Mighty Whale also helped at making calmer sea conditions behind the device by clipping the wave amplitudes, and thereby served a second purpose as a floating breakwater structure. The device was kept afloat by the buoyancy chambers along its perimeter and two vertical fins ensured the device to be laterally stable [12].

2.2 Over topping systems

Overtopping devices let the waves into a storage at a higher level than the calm sea surface and allow the collected water back to the sea, through turbines. It can be either on shore like TAPCHAN or offshore like Wave Dragon. Potential energy of water is used rather than the kinetic energy of waves hitting the ramp. The advantage of the over-topping system is less fluctuation in power. [13].

2.2.1 TAPCHAN

TAPCHAN or Tapered Channel wave energy concept uses a channel of a width which gradually decreases towards the end, thus pushing water off the ramp and flow through the turbines.

Narrowing of the channel increases the amplitude of the waves as they moves towards the cliff and spill over the ramp and get stored in the reservoir at a height above the sea level [14]. The water is allowed to flow back to the ocean through a turbine connected to a generator.

2.2.2 Wave Dragon

The Wave Dragon has a couple of reflectors/ramps where water flows through and is guided onto Kaplan turbines where the mechanical energy is converted to electricity. Wave reflectors can increase the significant wave height and hence its energy capture [13]. Wave Dragon is constructed with air chambers underneath, so that the height of the floating structure can be adjusted to extract the maximum energy capture and also serves to absorb the pressure of waves incident under the device thereby preventing device itself from moving [13].

Floating overtopping devices require tight mooring requirements because as waves brake on them, large forces would be incident on it. Mooring cost can be 2-3 times of the device itself [13].

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Uppsala University 2.3. ATTENUATOR

Figure 2.3: Overtopping WECs Wave dragon (left) and TAPCHAN (right) [13].

2.3 Attenuator

Attenuators are oriented in the same direction as the waves and flex according to the wave motion. They utilize the pressure difference over the devices between wave highs (crests) and lows (troughs) of ocean wave [14]. When a wave crest passes over a piston of the device, it is compressed inside and during a wave trough, the pressure decreases and the piston returns to the normal position. [14]. This motion actuates the hydraulic system which in turn drives the generator.

2.3.1 Pelamis

Pelamis WEC consisted of a string of cylinders coupled together like an articulated snake and moved about its hinged joints. When waves passed through the length of it, the cylinders moved relative to one another. The movement was converted to electricity through turbines.

It was the first WEC to be connected to a national grid (2004 in Orkney). In November 2014, the company went into administration and the devices are no longer being developed.

Technical failures and financial problems led to the failure of Pelamis, despite being the first grid connected WEC. See further analysis in section 4.7.1

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Uppsala University 2.4. OSCILLATING WAVE SURGE CONVERTER

2.4 Oscillating wave surge converter

As waves get closer to the shore, water particles move in an elliptical motion rather than a circular one. Oscillating wave surge converters produce energy from this movement. Devices are fixed onto the seabed not-so-far from the shore (depth less than 20 m). Oscillating water movement actuates a hinged displacer and the energy gets converted via hydraulic converters.

2.4.1 Oyster (Aquamarine power)

Oyster is a near shore based WEC that contains a flap that is moored to the seabed. Waves cause the flap to move back and forth. This oscillatory motion actuates hydraulic pistons which pump the water at high pressure onto a turbine on-shore and electricity is generated. Even though Oyster was a near shore device, exploitable energy was on par with the deep water devices [16] .

Since the Oyster device was almost immersed in water, the visual impact was less and seascape was not affected much. The proximity to the shore was advantageous in terms of easy maintenance but caused noise pollution and affected the aquatic life, because of its large physical size. The seabed fixed design and hinged flap favoured the survivability of device but the bigger size caused the capital cost to be high and site installation became difficult. Even though the design of oyster was somewhat simple, the optimization of energy absorption was quite difficult to achieve [4].

Figure 2.5: Oyster wave energy converter [17].

2.5 Point absorber device

Point absorber devices consist of a buoy that floats in or submerged below the water level. The size of the buoy is much smaller when compared to the wavelength it is interacting with. The heaving or surging motion of the buoy moves the prime mover of the generator and hence power is generated. Generally, point absorber devices are deployed offshore, where comparatively higher power density is available. The relative motion can be between buoy and fixed structure (as in Uppsala university WEC) or between buoy and moving reference (as in WaveBob).

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Uppsala University 2.5. POINT ABSORBER DEVICE

2.5.1 Uppsala University wave energy concept

Figure 2.6: Point absorber wave energy converter [18].

Figure 2.6 shows the point absorber concept by Uppsala University. The device uses a permanent magnet linear generator to convert the motion of waves into electricity. The buoy is connected to the stator through a line and a waterproof seal is used to prevent the seawater from entering the device [18]. The individual devices are connected to a marine substation on the seabed and connected to land through a power cable [19].

2.5.2 WaveBob

WaveBob was a heaving type of point absorber WEC which converts the relative axial motion between two buoys into electricity (see figure 2.7). The inner buoy is connected to a heavy body (body 2 in figure 2.7) that is used to increase the inertia in order to tune to the average wave frequency [20]. Captured sea water was used for increasing the weight and it helps in reducing the material cost considerably.

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Figure 2.7: WaveBob wave energy converter [20] .

2.5.3 WaveStar

WaveStar WEC had a bottom fixed platform with attached floating buoys that converted the motion of waves into electrical energy. The device consisted of many floats that move according to the wave movement and this motion pumped hydraulic oil into a common hydraulic manifold.

This motion rotated a hydraulic motor which was coupled to a generator [21]. The WaveStar had an unique technology for survival under storms, i.e, the floats would be lifted out of the sea during severe storm conditions. WaveStar made a prototype of 110 kW (see figure 2.8) and this prototype produced electricity for more than 2 years. The plan was to produce a full scale device of 600 kW with 20 floats but never materialised [22].

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Figure 2.8: WaveStar wave energy converter prototype with one float raised in storm protection mode (figure reprinted from [23] by license CC BY 4.0).

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Chapter 3 Methodology

In offshore industries such as oil and gas, plenty of data are available for risk analysis. Within a few years, this will hold true for offshore wind energy also as it is now established on a large scale globally. For example, data on accidents that have occurred in offshore oil and gas and in wind energy industry can be found in [24] and [25] respectively. But in the case of wave energy, the data available is scarce because of time-in-operation of any wave power device is too small when compared to other offshore industries. So gathering of data about risks in wave energy was a big challenge. Since data is scarce, the methodology or method of analysis could not be determined initially. The way of assessment would depend upon the data available. So there is very little available literature on actual failures. One model of analysis may fit to certain type of data, but not to data in other section.

First step was to gather as much data as possible. Literature research was done by extensive search in Google scholar and Uppsala university library with keywords risk analysis, wave power risks, wave energy barriers. The majority of articles were published before the failures happened. But a couple of study reports and some technology news could shed light into the topic.

An online survey was created and send out to the various researchers and industry experts in the field in order to study their experiences and expert opinions See Appendix A. In the survey, respondent had the opportunity to answer anonymously so the developers could share the experiences without fearing negative consequences for their company. A similar approach was undertaken when data for risks in oil and gas sector being gathered and led to the formation of offshore and onshore reliability data (OREDA) database.

3.1 Risk analysis

This project assesses the various risks faced by wave energy technologies or developers on their way to development. Risk refers to positive or negative outcome of uncertainties. Risk can be defined as likelihood of something undesirable that happen within specified time or circumstances [26]. The risks can be quantified in terms of frequency or probability, severity and combination of these parameters [13]. Risk assessment is the process of identifying the risks, analyzing them and evaluating the outcomes. In other words, it is a structured process to determine how project goals are affected.

Positive risk means outcome of risk is beneficial to the project or device or the entity. Nega- tive risks means the outcome would affect adversely that can be mild or severe or catastrophic.

Most of the offshore risk analysis concentrate on risks posed by or caused by the system to the outer world for example, fire, environmental risks and much more. In this project, we are considering the risks for the system itself from the outer world or within the system.

Risks can be analysed by either Qualitative or Quantitative methods. The former method

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Uppsala University 3.1. RISK ANALYSIS

identifies and analyzes risks in terms of probability of events to happen and their severity whereas latter method analyze risks quantitatively or in measurable terms. The qualitative method is selected here based on the requirement and the data available.

According to the American Bureau of Shipping (ABS), risk analysis is the process of identifying what can go wrong, how likely is it to happen and the possible effects of it. Risk analysis combines engineering, statistics, human behaviour etc to analyse the possibilities and effects of risks [27]. Coming to the risk analysis model, different types of qualitative risk analysis techniques are

• HAZID or Hazard Identification involves the identification of possible hazards and its likelihood, impacts etc. It is normally done as early as possible and required changes would be made in the design or operation. The likelihood of the hazard to occur is indicated as extremely unlikely, remote, occasional, probable and very frequent.

• HAZOP, or Hazards operability analysis consists of the risk identification and analysis of its possible outcomes and effects. On contrary to HAZID, in HAZOP the starting point of analysis is the deviation from normal operation. Certain keywords or guide words are used to denote these deviations for example, NO or NOT, MORE, LESS, AS WELL AS etc.

• FMEA or Failure Modes Effects Analysis breakdown the system into its lowest possible individual component and analyses the probability and effects of it failure and the effects of failure on the system as whole. It can be the most useful method for electrical or mechanical systems [27]. [28] shows a FMEA analysis done on an experimentally designed WEC in lab.

• SWIFT or Structured What IF Technique is a technique through which all probable causes are considered in a way that What is the outcome of different conditions and possibilities [29].

In this project, possible hazards have been identified, their likelihood and severity estimated, and also analyzed possible effects and risk mitigation methods. Thus the methodology involves elements from both the HAZID and HAZOP methods.

The data available regarding the risks in wave energy are scarce and it is not easy to list and prioritize the results (from Survey response). In qualitative risk analysis of wave energy devices, real struggle was encountered in finding the occurrence or frequency of risks or failures rather than type of failures or risks. So an alternate is to list the possible risks in each category such as technical, economical, environmental etc. and their causes or causing factors. The description of each risks and examples are given in the section Results. In some cases causing factors can be common to different risks or overlapping in nature. A similar method was suggested and used on onshore and offshore wind energy by Nadine Gatzert and Thomas Kosub [30].

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Uppsala University 3.2. SURVEY

Risk category Description Causes

Environmental Risks arising due to environmental factors, such as from ocean environment,

and storms

Harsh ocean environment, flora and fauna of ocean

Regulatory risks Risks due to long consenting processes,

conflicts in interests

Lack of policies and uncertainty from authority’s perspective Economic Risks arising due to the

uncertainty in costs and difficulty in finding

investment

Cost of components, under performance,difficulties in

securing investments etc.

Technical Risks arising due to drawbacks in design and

other auxiliaries or components

Design, components, human errors

Management Risks arising due to uncertainty in the supply chain, revenue; due to lack of experience or knowledge

Lack of personnel with relevant expertise, diverging interests of developers and investors Table 3.1: Table of classification of risks [22] [30].

3.2 Survey

Based on the above classification, data was collected from various sources such as reviewed articles, reports, technology news reports and an anonymous survey was constructed, distributed and sent out to various experts in industry and academia. The data collected is presented in the following sections as list of risks and various case studies or examples.

In total 21 people responded to the survey, all of them being experts from the industry and academia. One of them had experience of leading an WEC concept which is extinct as of now. Since a qualitative analysis is being done in the project, it is the quality of responses rather than their quantity (required for quantitative analysis) that is relevant, hence number of responses proved to be sufficient.

In the survey, the first two questions collected data about the background of respondent, i.e, industry or academia and the area of expertise with WEC device he/she has experience with.

Question 3 was framed in a way that each respondent could select the type of risks he/she had experienced. Further questions were selected based on the response.

A common structure was used for questions regarding individual risk types (except technical risks), such as marking the severity of risks on a 5-point semantic differential scale ¹ based on development phase in which risk was faced, consequences of the risks and possible mitigation methods in their opinion.

For the technical risks category, in addition to the above general questions, a question on

1Semantic differential scale is used to express an opinion or rating on a statement or idea, with bipolar or opposite meaning adjectives on either ends [31]

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Uppsala University 3.2. SURVEY

risks on subsystem level or component level also was asked, in order to get more insight on risks faced at component level (Questions 3.1.1.1 and 3.1.1.2).

The fourth question was about to rate or rank a list of vulnerable or most common barriers for WEC, based on their severity. Next two questions were about free text answers on severe risks faced by WEC and the feedback on survey.

The survey was built in a nested way, such that the respondents were taken to more detailed questions if they responded positively to questions. For example, if a respondent answered that he/she had no experience from technical risks, he/she was not shown the detailed questions about technical risks. The full survey is shown in appendix A.

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Chapter 4 Results

There are many risks or barriers that hinder the development of wave energy device or as a technology. Unlike many other renewable energy technologies, wave energy technologies have not shown any signs of convergence to a common point or design yet (as in wind energy, most of turbines uses 3 blade horizontal axis now). Apart from technological risks, the harsh ocean environment can be challenging for any device in it. A third factor that would be a hindrance to any industry or a technology in its premature stage is the economic or the financial factor.

Many companies or concepts went bankrupt in recent years or stakeholders backed out. These risks or barriers can be seen in any renewable technologies, if we go into the history, for instance, offshore wind power.

In this chapter, the results from the survey will be presented and connected to the knowledge gathered from literature.

4.1 Results from survey

The survey was sent out to experts in academia, industry and policy making. Three fourth of total respondents were from academia and others were from industry and a few from public authority and funding agencies.

95% of respondents had experience with wave energy and others had experiences in related offshore industry or a few had experiences in industry as a whole from policy perspective.

The response from the survey is given in figure 4.1. The number indicates the percentage of respondents that acknowledged that type of risk in wave energy industry. (Respondents could select more than one option.) Most of them experienced technical and economical risks or acknowledged the risk associated.

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Uppsala University 4.2. TECHNICAL RISKS

Figure 4.1: The response from survey: Risks faced.

Each of these risk categories will now be analyzed in separate subsections.

4.2 Technical risks

A technical risk arises either due to the design of device itself, any design parameter behind the screen or any connected or auxiliary systems such as external grid connection. The technical risks are interconnected to other risks. For example, environmental risks such as storms or corroding ocean environment can cause glitches in power production or the survivability of the device itself.

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4.2.1 Technical risks during installation phase

Installation phase risks refers to the risks that are faced by wave energy devices or technologies prior to operation phase or before they start generating power. It can include the design phase risks, offshore installation, and grid connection.

4.2.1.1 Design phase risks

The wave resources can vary significantly in terms of wave height, wave period etc. WEC should be designed in order to harness energy from varying wave conditions and at same time cope with fatigue from repetitive loads and extreme wave events. The design of WEC should be made by considering the extreme wave events also. For example, stator current under normal operation should be low enough in order to accommodate or withstand the probable current under the strong wave conditions also [32].

4.2.1.2 Offshore installation

Offshore installation of wave energy devices in harsh ocean environments can be a strenuous task owing to the lack of suitable weather windows. The offshore installation procedure or deployment poses both technical and financial barriers. The requirement of precision and weight of devices are important factors to be considered while looking for economic alternatives [33].

One example for installation risks happened during installation of wave energy device (OWC) near the city of Thiruvananthapuram in India, Caisson was not seated in proper position it was intended. Subsequently wave forces and the monsoon followed, and damaged it beyond repair because the caisson was not designed for it [34].

Offshore installation involves the permitting phase (for installation), getting the resources such as vessels or skilled personnel (for example, divers) and the actual installation. Aforesaid requirements before offshore installation are related to legislative or management type risks.

Hence it is evident that risks are moreover interconnected between each other.

4.2.1.3 Grid connection

After generating power, the power has to be carried on to the load centre, which would be onshore. For a shoreline or nearshore device, either the power generation would be onshore or a platform for transmission switchgear can be built nearshore. But in the case of offshore devices, it takes more effort. The connection from a floating wave energy device is taken to the seabed and from there the power is carried through the undersea cable. Typically grid connection of wave energy comes under the responsibility of the grid owner. But grid utilities want to avoid underutilized transmission lines at any point of time and tend to ask for the maximum utilization of their equipment.

Depending upon the charging regime, as shown in figure 4.3 the costs and development of transmission infrastructure and grid connection can be burdened on the device developer [35].

Even though shallow charging regimes are preferred in order to encourage or to protect the wave energy developers, grid connection can be posed as a challenge to the developers.

Medium sized wave energy devices have to be connected to a 110kV infrastructure, which would be near shore. Average distance of northern European wave farms lies in a range of 20-50km from the coast and hence cost of cable would be significant [35]. Larger farms situated offshore have to be connected to the high voltage network which is further distant from the shore and hence it results in high costs [35].

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Figure 4.3: Grid connection schematic diagram with charging regimes. Deep charging means the cost of grid from the device to the existing grid to be paid by developer [35].

4.2.2 Technical risks during operational phase

4.2.2.1 Component failures

Component failures can either be the result of lack of maintenance, inadequate or improper components, extreme events such as storms or long term wear and tear. For example, the failing component can be a shackle or chain and a connection line failure can lead to buoy breakage.

Sealant failures such as casing or O-ring seal failure can cause the generator to flood [36].

Component damages and the damage occurred to float of WaveStar are listed in performance evaluation update of WaveStar prototype [21].

In response to the question where respondents were asked about the most risk prone component or subsystem, majority had a view that mechanical parts such as mooring lines, mooring connectors (shackles) and hydraulic part are more vulnerable to the failure.

“For a point absorber, it is the buoy line guiding system at the top of the WEC superstruc- ture...”

“Shackles, mechanical components, sealing. ”

“.... Insufficient resilience of cables, connectors, attachment points. ”

“Depending on the site the mooring system is critical plus having made a 100% correct strength calculation of the hull. ”

“object captured energy will be under the action of storms and encounter with the highest risks ”

“Hydraulic PTO”

Full answers are given in appendix B

Mooring lines keep the WEC device in its place, while allowing it for the motion in

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to the station keeping (passive mooring), for some WEC concepts, the mooring system plays an active role in the hydrodynamic interaction with the waves and hence can affect the power extraction [40].

Conventional offshore and shipping industry also suffer from mooring failures. Mooring failures can even occur in premature stages, i.e. less than 10 years into life [41]. Johannes Palm lists excess loads, (especially snap loads) ¹ and fatigue of the line as the major causes of mooring line failure [42] whereas a slightly different opinion also found in Amog consulting web page [43], that is fatigue and design problems are the predominant in causing mooring failures, and then comes overload.

The factors discussed above are the risks on mooring systems, but there are risks due to mooring system also. Mooring system can affect the power take off by interacting with the waves [20] and cost of WEC, which is discussed in economical risks.

4.2.3 Effects and mitigation of technical risks

Figure 4.4: Probable effects of technical risks, results from survey.

Figure 4.4 shows the results from survey about the probable effects of technical barriers. Num- ber indicates the percentage of respondents experienced or were aware of the risks. for instance, 75% of respondents think that technical barriers can impart severe difficulties that affects the overall operation and development.

Figure 4.5 below shows the probable effect of technical risks on various subsystems during different development phases, from survey. The number indicates the percentage of unique respondents who experienced or acknowledged the risk. (Respondents could select more than one option, so percentage can be some times more than 100). The overall response to this question was low compared to other questions.

It is evident from the figure that storms or other extreme wave conditions impart most damages to the WEC. From the figure, one can conclude that mooring lines and mooring

1Snap loads occur when line is quickly re-tightened after a significant period or amount of slackness. DNV-GL recommend such conditions to be as low as possible. [39]

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connection points are vulnerable to damage and pose a serious risk. One survey respondent, who had experience in leading a wave energy project, indicated that a hydraulic PTO can be more prone to damages than other subsystems.

Figure 4.5: Probable effects of technical risks on subsystems by development phase, results from survey.

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Uppsala University 4.3. ECONOMIC RISKS

reliable suppliers with proven track record rather than relatively cheaper alternatives with less experience [30].

4.3 Economic risks

The uncertainty in the industry may cause the developers to find it difficult to raise the capital for the device and accounts for one of the major barriers in wave energy industry [44]. As of now, financial barriers are a major hurdle for wave energy devices from reaching commercial production [45] [46]. Many wave energy concepts have been ceased to operate owing to the financial problems. (Pelamis, Wave Bob and much more) [22]. The majority of wave energy developers are start-up companies or university spin offs which means financial support is crucial for growth. In EU, while some countries (Italy, Portugal and UK) increased the support for marine energy (wave and tidal) during the year 2017-2018 some other countries decreased or stayed at same amount of support (Sweden, Ireland and Norway) [47]. The current cost of energy is high for the investors to express their interest in wave energy. Wave energy faces a competition from mature technologies like offshore wind energy [44].

Table 4.3 shows various economic risks that wave energy concepts are likely to face.

Risk sub category

Probable point of

impact

Impact Examples Suggested

measures

Inability to secure funds

At any stage of development

Premature failure

WaveBob [22] National /Interna- tional support High capital

cost

Manufacturing materials, installation

Concept may not hit the

ocean.

WaveStar [22] National /Interna- tional support, Costly

maintenance and repair

OPEX Increased

OPEX, generated energy would be

no more economical

Divers and equipment can cost Thousands of euros per day

[48]

National /Interna- tional support;

flexibility of funding

systems Table 4.1: Table of economical risks.

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Figure 4.7: Economical risks through phases of development (from survey).

As for the technical risks, survey respondents identified the installation and operational phases as posing most severe economic risks, these two phases will now be analyzed with respect to economical risks in below subsections.

Costs of wave energy generation depends upon various factors such as location, device and technology. The dependency on location can be attributed to the infrastructure required and the availability of resource. Costs associated with WEC are called as cost centres (named by carbon trust ², UK) and consists of [49].

• Device

• Mooring and support

• Installation

• Operation and Maintenance

• Annual energy production

• Decommissioning

Offshore wind energy also seems to have similar economics to wave energy and have installation and maintenance being risky and costly. Onshore wind power tends to have a more stable market and support compared to offshore industry and hence easier in acquiring investments.

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Figure 4.8: Cost of WEC [50].

Figure 4.8 shows the components that determines the levelized cost of energy (LCOE) for wave energy. Levelized cost of energy is an indicator of economic viability of an energy source by considering a minimum rate of return [51].

The LCOE is given by expression [52]:

LCOE = F CR ∗ CAP EX + OP EX AEP

where

• FCR is the fixed charge return.

• AEP is annual energy production.

• CAPEX and OPEX are capital and operating expenditures respectively.

Different components that determines the LCOE are discussed in subsections below.

4.3.1 Economic risks during installation phase

Economic barriers posed from the planning or design stage to the installation phase is discussed here. As for the technical risks, survey respondents identified installation and operational phases as posing most severe economical risks as seen in figure 4.7. These two phases will be discussed with respect to economical risks in below subsections.

4.3.1.1 Capital costs or capital expenditures (CAPEX)

Device cost is constituted by the cost of structure, fabrication and painting. The structure costs is the major part of the device cost, in most cases [49]. The hull or structure has to face or interact with the waves and currents and most susceptible part to the mechanical forces. The structural costs are simply not volume times price of material, it depends upon the complexity

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and fabrication of the structure [49]. The increased costs can make the device and entire project go at stake.

Mechanical and electrical costs are constituted by the components that extract energy or the real working part of the WEC. for example hydraulic system or generator or gearbox.

These costs are highly device specific. Design is based on the site, wave resource available and maximum power take off (without destruction of device). It is not economical to design a device that extracts maximum power because it would be under utilized most of the time, as wave conditions with high power are less probable [49].

Mooring helps the device to stay in place while letting it for the independent movement for the power production whilst withstanding the hydrodynamic forces exerted by the sea.. An economical solution for mooring and supporting a floating WEC is a major hurdle in designing.

The cost of establishing a mooring point and supporting WEC on it, can be large [53]. According to the Wave Energy Planning and Marketing (Waveplam 2009) report, mooring costs comes to approximate 10% of device cost [54] [55].

Shipping costs and Installation can be high as one third of the device cost [54]. Transporta- tion costs depends upon the location of deployment. GJ Dalton suggests that it is better to do manufacture or assembly locally than transporting the entire unit and local shipyards and expertise of skilled labour there can be utilized for the same [5]. The reason for the wave energy company Seabased to leave Lysekil can be read together with this scenario . They stated that they could not manufacture generators in Lysekil owing to the inability to weld and paint and lack of accessibility to deep port [56].

Installation methods depend upon the site, type of device and sometimes local weather at the time of the year. Equipment such as tug boats, barges and heavy lift vessels would be needed, and skilled personnel which costs thousands of euros a day [48]. In addition, grid connection costs also comes under capital costs which is explained in technical risks See 4.2.1.3.

4.3.1.2 Lack of financial support

As mentioned earlier, inability to raise funds have been a major barrier in wave energy development [44]. It can be either research support or support for the actual device or project. The lack of right expertise and research funding is a major barrier [22]. Sometimes lack of flexibility in criteria for public support for research can be a hurdle in providing support. For example UK’s MRDF programme set a criteria of a competitive R&D, and ’all set’ for commercial generation, to give out the support of £42M(total) but none of then concepts could satisfy it, which resulted in fund going lapse, in 2006 [22].

Many wave energy concepts stopped to exist when their supply of money faded, which shows that project finance is an important factor for any ocean energy concept [22]. In ocean energy, the projects have been funded by both public and private investors. In Europe, half of the investments came from private investors in 2011 whereas 32% from member states and EU funds provided 18% [57]. As the subsequent failures occurred, private players tend to withdraw from investing [44]. Wave energy requires a more stable and long term funding.

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countered, and the supplies required for normal operation (for example, lubricating oil). Main- tenance activities can be classified as planned and unplanned maintenance and repair. In order to minimize the downtime or maximize availability, preventive maintenance is inevitable. It includes the cost of special purpose equipment, skilled personnel and planning of activities according to the weather window. Any probable deviation in the plan would increase the costs [58]. In addition, maintenance would possibly be required after any storm or cyclone, to ensure the device is working properly. According to wave power feasibility study in San Francisco 2009, maintenance costs can be up to 3-5% of the total capital cost [58].

A major overhaul may be needed when device reaches half of its lifetime in order to ensure the survival of the device [54]. It may include but not limited to, replacement of any hydraulic or moving parts and re-painting of the structure. The cost depends on the wear and tear it had and the part to be replaced. Approximately 10% of total capital cost can be attributed to the major overhaul [59].

Annual energy production depends on the site, energy capture of device, climate and the availability of device. This constitutes the major income of any wave energy technology. As per the Strategic Initiative (SI) ocean report 2013, levelized cost of energy is defined as the ratio of sum of CAPEX and OPEX to the lifetime energy production [50] (see figure 4.8).

Decommission also costs a considerable amount as almost same steps like deployment have to be repeated. It involves carrying device onshore and disposing or reusing. All devices and their parts have to be removed except for some heavy anchors or supports, as they might have formed a shelter for marine life or artificial coral reef [54].

4.3.2.2 Risk of exceeding budget

Since the wave energy sector is not yet mature, a cloud of uncertainty on actual costs linger around it. Actual costs of deployment or maintenance are not shared within the industry or developers, so a handful of reserve budget is required, which may deter investors [22]. In addition, unfavorable weather events can make any planned events to be cancelled or postponed, which results in additional costs or the funds to go in vain.

Even though usage of insurances and weather based financial derivatives are favored by renewable energy developers, small developers or projects might find it to be difficult, as paying higher premiums for insurances would not be cost effective for them [60].

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4.3.3 Effects and mitigation of economical risks

Figure 4.9: Probable effects of economic risks, results from survey.

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Uppsala University 4.4. LEGISLATIVE RISKS

may be postponed or fail. In that cases allowed funds or financial support should not go lapsed or in vain, leaving another attempt to be cash strapped. One survey respondent highlighted this possibility

“... often there is only funding for one deployment (since they are so costly). If it fails, there is no funding for second attempt”.

In addition to the direct revenue by energy generation, the wave energy industry can enhance income through other additional ways. Credits earned from carbon emission reduction (by using renewable energy) and the development or reactivation of ports/shipbuilding or related local markets can be used to enhance the revenue paths of a WEC project [61].

4.4 Legislative risks

A number of legislative bodies or agencies control operations in a sensitive environment like oceans. It can be environmental, commercial, technical or military interests. For a WEC device to be deployed in sea, many hurdles have to be passed. Before installation and power generation, the developers need approval or consent from all those agencies and have to follow a number of guideline and regulations. For example, under sea cable laying and connecting to grid usually demands separate approval processes [62].

Wave energy technology now faces a row of hurdles to be passed to obtain license, due to legal requirements raised by a number of agencies. Even though wave energy industry has been in existence for a couple of decades, it is yet to emerge as a mature technology. So it lacks a clear or definite path for passing the various legal requirements for offshore deployment.

As of now, approval process and requirement for environmental impact assessment (EIA) are regarded as a major barrier owing to the absence of dedicated regulatory frameworks to support offshore renewable energy [62]. In order to develop a comprehensive EIA itself, lack of sufficient information also poses a hurdle.

Figure 4.11: Legislative risks through phases (results from survey).

30% of the survey respondents answered that they faced or acknowledged the role of legislative barriers in wave energy industry. It can be spread across the different phases of development

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Uppsala University 4.4. LEGISLATIVE RISKS

as shown in figure 4.11

Survey respondents were of the opinion that regulatory barriers are of mild nature when compared to others such as technical or economical barriers.

Possibility of severe risk in wave tank testing phase can be due to the less availability of testing centres and the lack of available funds, which is an economic risk.

4.4.1 Legislative risks during pre installation phase

Legislative barriers tend to be concentrated towards pre installation stage as most of the legal processes are required for ”consent” to install the device in the ocean.

4.4.1.1 Number of authorities involved

As stated above, a number of agencies and authorities are involved in consenting a marine energy project. The system and pattern varies from country to country, those who have a complicated legislation system tend to have more number of authorities. Developers have to go all the way through this system to get their device in water. Around ten agencies or authorities are involved in consenting process in Sweden [63].

In order to ease the whole consenting process, some countries tend to suggest a ”one-stop- shop” [62] for ocean or marine energy sector. The approach was to streamline these processes or a single agency to handle all requirements of a WEC device to be deployed in ocean. It has been proven successful in countries that utilized it. In Sweden, there are no special legislation covering the consent for wave power projects and considered similar to that of offshore wind power. The consenting process starts with approach to county administration (L¨ansstyrelsen) and then goes to different authorities or agencies, until the decision from environmental court (Mark-och Milj¨odomstolen). It can take up to many years and if objections come into way, it can be delayed further [64]. However, once coordinated measures were taken it reduced to approximately two years [62].

4.4.1.2 Marine spatial planning

Various industries such as fishing, leisure, transport and energy have various interests in marine environment. Sometimes, the allocation of ocean spaces are given on a ”first come -first served” basis, which would not always be the correct approach [64]. As per the definition of In- tergovernmental Oceanographic Commission (IOC) of UNESCO [65], “Marine spatial planning is a public process of analyzing and allocating the spatial and temporal distribution of human activities in marine areas to achieve ecological, economic and social objectives that have been specified through a political process.” As the name suggests, marine spatial planning (hereafter mentioned as MSP) is a coordinated effort to make use of ocean resource in a smart way without interrupting each other. The emergence of wind power necessitated the need of MSP in many countries. Unless a central or coordinated approach is not present, MSP would not

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Uppsala University 4.5. ENVIRONMENTAL RISKS

The requirement for EIA varies among the countries. Sweden requires EIA for any energy installation in marine environment as they are considered as potentially harmful to the environment [62]. Some countries might require EIA based on the capacity of plant (for ex.

above 10MW EIA is required). Setting requirement for EIA based on capacity only would not be beneficial for ocean energy, as the study time and cost for a temporary, single device and permanent, full scale installation can be same.

4.4.2 Effects and mitigation of legislative risks

Regulatory barriers can be troublesome for developers and authorities at same time, because of the less experience and available information. Developers and regulators need to know what information they require from the other party, absence of clear guidelines is the reason for the miscommunication [62].

One example for delay due to regulator barrier was in Mutriku WEC, in terms of EIA.

The breakwater structure had an EIA and since wave energy project was considered as a demonstration project, full EIA was out of question. But an opposition for breakwater EIA, which demanded combined EIA for breakwater and WEC blocked the project start. Verdict in resulted court case did not demand a full EIA, but case lagged the project by more than 3 years.

Negotiations for feed in tariff (FiT) also delayed the project. Mutriku WEC commissioning took a long 7 years from the ’consent’ [67].

A possible solution for the EIA requirement problem is to use the pre-consented test centres for testing or prototypes. for example, Nova Scotia in Canada. Even then, specific usages or tasks can demand requirement of EIA, like laying of under sea cables. Another solution for easing the EIA requirement is to make risk based approach for approvals. So the requirement of EIA will be based on technology, site environment and size or period of deployment and would be less with less sensitive environment [68]. For example, there is no need of stringent requirements for test installations as required for a permanent installation.

One stop shop approach is a single contact that can deal with all the consents related to marine energy installation such as ocean space usage license, EIA requirements. The approach streamlines the consenting process, and proved to be effective from both developer and regulator perspective in nations where it was tried (for example, Marine Scotland in Scotland) [62].

4.5 Environmental risks

Wave energy devices work upon the energy of ocean waves, so they have to face the sheer force of ocean waves or the corroding environment of ocean to survive. Environmental risks means the barriers it has to face in the ocean environment such as storms, interaction with marine organisms and the limitation posed by the sea towards the maintenance activities.

Table 4.2 shows the various environmental risks, their impact, examples and suggested measures.

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Risk sub category

probable point of

impact

Impact Examples Suggested

measures

Storm/Rogue waves

The whole structure/one or

more parts, mooring lines.

Severe, can damage the

device.

Kværner (Norway) [69];

Wave dragon stranded after storm Gudrun

[70].

Proper design and

prior risk analysis.

Lack of sufficient weather window

Availability ; Economy

Delay in installation or

maintenance

Pelamis had to shift their re-installation of

device after a fault rectification in 2007 (Portugal)

[5] [71].

Better planning and access

to resources.

Biofouling Mooring lines, buoy

Increases weight

; affects motion;

affects performance and decreases

fatigue life

Biofouling on Oyster’s flap

when it was submerged for 9

months period before commissioning,

see figure 4.14 [72]

Antifouling paints and

maintenance.

Corrosion Mooring lines, hull

Accelerated fatigue

Kværner (1988):

corrosion of bolts caused failure in storm

[69]

Selection of suitable

materials, mainte-

nance Table 4.2: Table of environmental risks.

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Figure 4.12: Environmental risks through phases, from survey.

As evident from the figure, environment risks are prominent in operational and installation phases offshore. Environmental risks are almost null when they are onshore or prior to installation.

4.5.1 Environmental risks during operational phase

The barriers posed by environmental factors are experienced mostly during the operational phase except for the weather window required for offshore installation, cable laying or grid connection.

4.5.1.1 Variability of wave resource

Wave energy as most other renewable energy resources, is not predictable or in other words, vary in the temporal and spatial regimes. Even though the resource is estimated prior to modelling or designing, variations may occur and cannot be controlled. Variation in the wave resource is entirely natural or say, environmental phenomenon and the effect can be technical (power production or component failures) or related to economic risks.

Wave energy is more predictable than solar and wind but less predictable than tidal power.

[73]. Since the prime cause behind the wave formation is wind, there can be a relation between variability in wind and wave. Wind and wave variability are generally relative but wind varies more when compared to the wave [74]. Due to the variability, a step change in production can occur (change in output over a certain time) which has to be certainly at minimum as variation in power production would not be desirable from grid or utility perspective. However, step change in production can be a good indicator for comparing sites [73].

A typical WEC cannot convert whole wave energy available at a location to electrical energy.

In fact, there is a range between lower limit or threshold, above only which WEC start to extract power and upper limit, above which WEC should go to survival mode and no energy conversion would take place [75]. A similar limitation is applicable in the case of direction and frequency also. From a practical point of view, a WEC device is sometimes tuned to certain direction of waves and a range of frequency [75].

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Spatial variation can be mitigated by using WECs of different type. They will extract different portion of power available as they are designed to work at different wave parameters and optimise the power extraction at different regions or bands [73]. The combination of wave and wind power have shown to be smoothing the power production curve rather than allowing for step change in productions [67].

Figure 4.13: Comparison of wave power, wind power and combined wave-wind production [67].

Figure 4.13 (bottom) shows the comparison of wave power, wind power and a 50-50 combined operations power production at Hanstholm in Denmark during January 2011. The WEC was a full scale prototype of the WaveStar device and the wind turbine was of Nordisk Folk- centre Renewable Energy. The rated power of wave and wind device was 110kW and 525kW respectively. Figure 4.13 (top ) shows the wind and wave resources at the site.

From the figure, it is evident that the wave power was smoother and combined production of wave and wind provided better availability of the power. The combined production never went to zero [67] .

4.5.1.2 Survivability in the ocean

Survivability against the strong forces of waves under rough climate is one of the key factors

Qualitative risks analysis on wave energy technologies

Examensarbete 30 hp Oktober 2020