Constructing the map of offshore wind energy potential along the coast of vietnam

This study aims to assess offshore wind energy potential in Vietnam using the Cross-Calibrated Multi-Platform CCMP ocean surface wind data.. 22Figure 4.2 Surface wind speed probability d

VIETNAM NATIONAL UNIVERSITY, HANOI

VIETNAM JAPAN UNIVERSITY

VU DINH QUANG

CONSTRUCTING THE MAP OF

OFFSHORE WIND ENERGY POTENTIAL ALONG THE COAST OF VIETNAM

MASTER'S THESIS

Hanoi, 2019

VIETNAM NATIONAL UNIVERSITY, HANOI

VIETNAM JAPAN UNIVERSITY

VU DINH QUANG

CONSTRUCTING THE MAP OF

OFFSHORE WIND ENERGY POTENTIAL ALONG THE COAST OF VIETNAM

MAJOR: INFRASTRUCTURE ENGINEERING

CODE: PILOT

RESEARCH SUPERVISOR:

Prof Dr Sci NGUYEN DINH DUC

Dr DOAN QUANG VAN

Hanoi, 2019

ACKNOWLEDGMENT

After two years studying at Vietnam Japan University, VNU, I would like to express

my sincere thanks to the Board of Directors, the departments and the lectures of Vietnam Japan University who have enthusiastically taught and created favourable conditions to help me in the process of studying and doing Thesis

In particular, I would like to express my appreciation and deep gratitude to Prof Nguyen Dinh Duc and Dr Doan Quang Van who directly guided and assisted the author during the process of implementing the thesis

I must express my gratitude to Dr Dinh Van Nguyen for his consistent support and guidance during the running of this thesis I have been extremely lucky to have a supervisor who cared so much about my work, and who responded to my questions and queries so promptly

Furthermore, I want to express my deepest thanks to Prof Hironori Kato, Assoc Prof Mai, Dr Phan Le Binh and Dr Nguyen Tien Dung for provided materials and valuable advice for me to make this thesis

My deepest thanks to Assoc.Prof Tomonori Nagayama who supported me during the internship in Japan He gave me very useful advice on my thesis I would like to thank all members of Bridge and Structural Laboratory, the University of Tokyo

From the bottom of my heart, I would like to express my deep gratitude to my family, thank my dear friends for taking care of and encouraging me during 2 years of studying at VJU

Vu Dinh Quang

ABSTRACT

Offshore wind energy is expected to have high potential to cope with increasing energy demand in Vietnam which is forecast to grow 2.5 times in the next 20 years This study aims to assess offshore wind energy potential in Vietnam using the Cross-Calibrated Multi-Platform (CCMP) ocean surface wind data The CCMP dataset is firstly validated against observational data from weather stations in the offshore islands in the Vietnam sea Assuming the hypothetical wind turbine LEANWIND 8MW, this study assesses offshore wind energy potential of four sea areas of Vietnam base on the temperature in the year In zone 1, the area around the location where have latitude and longitude are (19.8,108) respectively has the most potential offshore wind energy The offshore wind energy potential is the largest at the sea area of Binh Thuan province and Ninh Thuan province where located in zone 3 In zone 4, the sea area near Ba Ria - Vung Tau province has good potential energy Marine zoning can effectively increase the use of marine resources not only for a specific purpose but also in combination with other uses The government, investors can use the results obtained in this research in combination with regional conditions to select the optimal location of the offshore wind farm

Keywords: Offshore wind energy, CCMP data, Vietnam sea

TABLE OF CONTENTS

ACKNOWLEDGMENT i

ABSTRACT ii

TABLE OF CONTENTS iii

LIST OF FIGURES iv

LIST OF TABLES vi

CHAPTER 1 INTRODUCTION 1

1.1 Wind energy overview 1

1.2 Status of wind power development in the world 4

1.3 Status of wind power development in Vietnam 6

1.4 Research objectives 8

CHAPTER 2 LITERATURE REVIEW 9

2.1 Wind energy research situation in the world 9

2.2 Wind energy research situation in Vietnam 11

CHAPTER 3 METHODOLOGY OF RESEARCH 12

3.1 Methodology 12

3.2 CCMP dataset 13

3.3 Zoning the offshore wind resources 15

3.4 Estimation of wind energy potential 19

CHAPTER 4 RESULTS AND DISCUSSION 21

4.1 Data validation 21

4.2 Evaluation of spatial and temporal variation of offshore wind resources 26

4.3 Evaluation of wind energy and the variation for each zone 29

4.4 Capacity factor 34

4.5 Power distribution 40

CHAPTER 5 CONCLUSION 44

REFERENCES 46

LIST OF FIGURES

Figure 1.1 Installed wind power capacity in the world (Kaplan, 2015) 4Figure 1.2 Installed wind power capacity in the European Union (Council, 2012) 5Figure 1.3 Installed wind power capacity in the United States (Council, 2012) 5Figure 1.4 Installed wind power capacity in China (Council, 2012) 5Figure 1.5 Total installed wind power capacity of Vietnam and other countries by the end of 2013 (Luong, 2015) 6Figure 1.6 Location of wind farms in Vietnam 7Figure 3.1 Methodology flowchart of the study 12Figure 3.2 Major synchronous power sources and power transmission lines in Vietnam (EREA, 2019) 16Figure 3.3 Location of major ports and container terminals in Vietnam (data source: (SeaRates), (VPA), some in-land river ports accessible to large vessels) 17Figure 3.4 Four zones are considered in the study 18Figure 4.1 Meteorological stations on the map 22Figure 4.2 Surface wind speed probability distribution of the CCMP data and observed data at Co To station 23Figure 4.3 Surface wind speed probability distribution of the CCMP data and observed data at Bach Long Vi station 23Figure 4.4 Surface wind speed probability distribution of the CCMP data and observed data at Hon Ngu station 24Figure 4.5 Surface wind speed probability distribution of the CCMP data and observed data at Ly Son station 24Figure 4.6 Surface wind speed probability distribution of the CCMP data and observed data at Phu Quy station 25Figure 4.7 Surface wind speed probability distribution of the CCMP data and observed data at Truong Sa station 25Figure 4.8 Surface wind speed probability distribution of the CCMP data and observed data at Phu Quoc station 26Figure 4.9 Seasonal average surface wind speed within five years 27Figure 4.10 Wind speed average at 100 m from 2007 to 2011 28

Figure 4.11 Inter-annual wind speed at four islands period 2007-2011 28

Figure 4.12 Power curve of LEANWIND 8 MW turbine 30

Figure 4.13 Seasonal accumulated wind energy in zone 1 31

Figure 4.14 Seasonal accumulated wind energy in zone 2 31

Figure 4.15 Seasonal accumulated wind energy in zone 3 32

Figure 4.16 Seasonal accumulated wind energy in zone 4 32

Figure 4.17 Annual accumulated wind energy in four zones 33

Figure 4.18 Seasonal average capacity factor of turbine in zone 1 35

Figure 4.19 Seasonal average capacity factor of turbine in zone 2 35

Figure 4.20 Seasonal average capacity factor of turbine in zone 3 36

Figure 4.21 Seasonal average capacity factor of turbine in zone 4 36

Figure 4.22 Annual average capacity factor of turbine in four zones 37

Figure 4.23 Annual capacity factor at Bach Long Vi islands period 2007-2011 38

Figure 4.24 Annual capacity factor at Ly Son islands period 2007-2011 38

Figure 4.25 Annual capacity factor at Phu Quy islands period 2007-2011 39

Figure 4.26 Annual capacity factor at Phu Quoc islands period 2007-2011 39

Figure 4.27 Seasonal average power distribution in zone 1 41

Figure 4.28 Seasonal average power distribution in zone 2 41

Figure 4.29 Seasonal average power distribution in zone 3 42

Figure 4.30 Seasonal average power distribution in zone 4 42

Figure 4.31 Annual average power distribution in four zones 43

Figure 4.32 Inter-annual wind power density at four islands period 2007-2011 43

LIST OF TABLES

Table 3.1 Information of the CCMP dataset (NASA/GSFC/NOAA, 2009) 14

Table 4.1 Coordinates of seven meteorological stations of Vietnam 22

Table 4.2 Information of LEANWIND 8 MW turbine 29

Table 4.3 Maximum of seasonal wind energy (GWh/km2) 33

CHAPTER 1 INTRODUCTION

1.1 Wind energy overview

Renewable energy is the type of energy generated from continuously added sources

or sources that are considered infinite with human exploitation Renewable energy includes solar energy, hydropower, tidal energy, wind energy, biomass energy, geothermal energy

Wind energy has great potential from nature Wind energy is a clean and abundant form of energy and almost endless energy supply Wind energy originates from the Sun like most other energy sources on Earth Solar radiation, when exposed to the Earth, does not evenly distribute the heat on the surface of continents and oceans This differential heat distribution produces high pressure and low pressure, thereby producing pressure gradients between different areas To compensate for the pressure difference, the air mass from the high-pressure area will move to the low-pressure area, thereby creating wind Because the air has weight, moving air masses will generate kinetic energy This kinetic energy is converted into electricity by wind turbines Wind energy is one of the fastest growing energy sources in the world because it has many advantages such as:

 Wind energy is renewable and sustainable: Wind power will never be exhausted, unlike fossil energy sources (such as coal, oil, and gas) This makes

it a suitable source to provide sustainable energy

 Wind energy is environmentally friendly: Using wind turbines to generate electricity does not create pollution So wind energy is environmentally friendly compared to other traditional energy sources The process of exploiting non-renewable energy sources releases gases such as carbon dioxide (CO2) and methane (CH4) into the atmosphere In contrast, wind turbines do not produce greenhouse gases when generating electricity

 Wind energy can reduce fossil fuel consumption: The electricity generated from wind will contribute to reduce the pressure on demand for fossil fuels

such as coal, oil, and gas This can help preserve the exhausting supply of natural resources Therefore, natural resources will survive and support future generations longer

 Wind energy is free: Wind power is completely free and it will never run out Therefore, wind energy will be a choice to generate cheap electricity

 Wind energy has a small footprint: Wind farms are often built on fields, on hills or in the sea Wind turbines use less ground or sea area At these locations, wind turbines have little effect on the use of surrounding land

 Wind energy can provide power for far locations: Wind turbines can be used

to generate electricity in places where access to the national grid is difficult Wind turbines are a suitable and effective solution for remote locations

 Wind energy can increase energy security: By using local wind energy sources,

we can reduce dependence on other energy sources That could enhance the nation's energy security

 The wind energy industry creates jobs: The developing wind power industry will create more job opportunities all over the world Jobs related to the manufacturing, maintenance, and installation of wind turbines will require more manpower Wind power experts are also needed to determine whether the wind farm project is profitable

Besides the above advantages, wind energy still has some disadvantages One of them

is the wind turbine that creates noise pollution Another disadvantage of wind turbines

is to visual pollution In spite of the fact that many people really like the shape of the wind turbine, others don't As we implement more wind farm projects, people will become more familiar and accept

Wind power on the shore has a low wind speed, affecting noise and visibility so the economic efficiency is lower because the areas with potential onshore wind power have been fully exploited Some outstanding advantages of offshore wind power, especially with the community, the national electricity grid, and the ecological environment (Dinh & McKeogh, 2018)

 The offshore wind is suitable for electricity consumption because it is strong during the day In contrast, onshore winds are strong at night (as opposed to electricity consumption) Therefore, the cost of offshore wind energy storage and transmission will be reduced

 The offshore wind is more stable and higher capacity factor The forecast can reach 40-50% in Vietnam This will have many benefits for investors such as increasing the life of mechanical systems, structures, etc It also has great benefits for transmission and the national grid

 Transporting and installing large turbines easily by ship/barge Large turbines like 9MW with wings length of 80 m, 12 MW with wings length of 107 m, transporting large parts of the turbine on land are almost impossible but will

be easy on the sea

 CO2 emissions of offshore wind power are the lowest in energy forms (16g

CO2 / kWhe) Meanwhile, hydroelectric power is 28g CO2 / kWhe, nuclear is 33g CO2 / kWhe, gas electricity is 450g CO2 / kWhe, and coal power is 1050g

CO2 / kWhe (Kaldellis & Apostolou, 2017)

 Almost no impact on human life (noise during erection, operation and obstructing the vision are far away, especially the modern offshore wind farm

is usually over 10km from the shore)

 The use of large turbines will make the distance of turbine pillars far apart (above 1 km for 9 MW), so it will minimize the impact on the marine ecosystem (under the sea and in the air)

 Contribute to protecting national security, national sovereignty, and territorial waters

Therefore, the research into offshore wind energy potential is necessary due to it helps

to identify suitable areas for construction of wind power plants

1.2 Status of wind power development in the world

Since the oil crisis in the 70s of the 20th century, the study of energy production from other sources, especially from the wind has been promoted worldwide Currently, wind power is also one of the renewable energy sources with relatively low cost and fast growth in the world The installed wind power capacity from 2004 to 2013 in the world In 2013, nearly 35 GW of wind power capacity was installed (Kaplan, 2015) From Figure 1.1, we can see that the total installed power capacity increased nearly

7 times from 47.620 MW in 2004 to 318.105 MW in 2013 It can also be seen that the total installed power capacity increases continuously over the years

Figure 1.1 Installed wind power capacity in the world (Kaplan, 2015)

Currently, there are many countries in the world using wind power Europe, USA, and China are three major markets for wind power generation in the world Figure 1.2, 1.3 and 1.4 shown installed wind power capacity in the European Union, the United States, and China, respectively A glance at the graphs provided reveals some striking similarities between three areas in wind power development trends from 2001

to 2013 European and the US are two regions that have grown steadily of installed

wind power capacity over the years in the period 2001-2013 From Figure 1.4, wind power development in China can be divided into 2 phases in the period 2001-2013 Phase 1 is from 2001 to 2007 when wind energy developed very slowly in China Phase 2 is from 2007 - 2013 is the period when installed wind power increased dramatically in China

Figure 1.2 Installed wind power capacity in the European Union (Council, 2012)

Figure 1.3 Installed wind power capacity in the United States (Council, 2012)

Figure 1.4 Installed wind power capacity in China (Council, 2012)

1.3 Status of wind power development in Vietnam

Given the challenges of power shortages and effective adaptation to climate change

in the coming years, the plan to develop green energy from renewable energy sources

is a feasible solution to ensure energy security and environmental protection Recently, the Government of Vietnam has clearly defined the goals in the direction

of developing green energy In particular, wind power is considered a key area, because Vietnam is considered a country with good wind energy potential

The average gross domestic product (GDP) growth rate of Vietnam was 7.2% in the last decade (Luong, 2015) The average growth rate of energy demand has reached a very high level, about 15% per year It is twice bigger than the GDP growth rate (Luong, 2015) This means that the economy will lack a large amount of electricity, and the shortage rate can reach 20-30% per year Therefore, Vietnam needs a strategy

to ensure energy security by expanding the exploitation of traditional energy sources

on the one hand; on the other hand, even more important, developing new energy sources, especially clean and renewable energy sources, typically wind power

Figure 1.5 Total installed wind power capacity of Vietnam and other countries by

the end of 2013 (Luong, 2015)

Figure 1.5 shown the cumulative installed wind power capacity by the end of 2013

of Vietnam and other countries By the end of 2013, the UK, Italy, France, Canada, and Denmark are among the top 10 countries with the largest installed wind capacity Compared to those countries, Vietnam has much smaller installed wind power capacity compared with countries in Asia such as Japan, Taiwan, South Korea, and Thailand, installed wind power capacity in Vietnam is still lower Although the potential for wind power development in Vietnam is greater than one of them

Figure 1.6 Location of wind farms in Vietnam According to statistics, as of September 2012, a total of 77 wind power projects have been registered in 18 provinces with a total registered capacity of 7,234 MW (registered capacity of the first phase is 1,488 MW) (Khánh, 2011) The area is mainly concentrated in the Southern Central and Southern provinces, with a total registered

capacity of nearly 5,000 MW, the capacity of each project from 6 MW to 250 MW Figure 1.6 shows the location of onshore wind farms and offshore wind farms in Vietnam Currently, most wind power plants are onshore wind farms Wind farms in the offshore area have just started to be interested in the last few years Current wind projects focus mainly in the central provinces and the southern provinces In general, wind power projects are most concentrated in the provinces of Binh Thuan and Ninh Thuan, which are also two provinces with the most abundant wind potential in Vietnam

Wind turbine suppliers in Vietnam: Besides some of the suppliers have participated

in the projects as Fuhrlaender (Germany), Vestas (Denmark), and GE (US) There are also other suppliers who are showing interest in Vietnam markets such as Gamesa (Spain), Nordex (Germany), IMPSA (Argentina), Sany, Shanghai Electric and GoldWind (China)…

1.4 Research objectives

The thesis has two main objectives:

 Construct maps of offshore wind characteristics in Vietnam

 Construct maps related to the assessment of offshore wind energy potential

in Vietnam

The first research objective is to construct maps of offshore wind characteristics in Vietnam The research will analyse seasonal wind speeds and wind directions The average offshore wind speed is also important information combined with turbine height information, so the study has constructed a map of average wind speed at a height of 100m

The second research objective is to construct maps related to the assessment of offshore wind energy potential in Vietnam In support of a more accurate assessment

of the potential of wind power development in Vietnam, this study has divided Vietnam's sea into 4 small regions and constructed maps of energy generation distribution, capacity factor, and power distribution for each region

CHAPTER 2 LITERATURE REVIEW

2.1 Wind energy research situation in the world

Countries around the world are facing problems of environmental pollution and energy security Renewable energy emerges as an optimal method to solve those problems (Dincer, 2000) The use of wind energy has positive impacts on society and environment such as the reduction of greenhouse gas emissions, creating job opportunities, and promoting sustainable development (Dinh & McKeogh, 2018) The exploitation of offshore wind energy can be greater than 50% of the onshore wind power plants because the wind speed is more stable and larger (Dinh & Basu, 2013) In addition to providing electricity onto a country’s grid, offshore wind power plants help to improve the quality of life in the island area where far from the shore (Zheng, Xiao, Peng, Li, & Du, 2018), and potentially supply power to gas for renewable fuel (Dinh & McKeogh, 2018)

In order to have a successful wind energy development project, accurate evaluation

of the wind potential is very important (Gualtieri, 2019) There are many studies assessing wind energy potential in the world using data obtained from satellites and wind observation station Murat et al (2007) used the dataset to figure out wind energy potential in Kirklareli, Turkey Cumali İlkiliç (2012) also used the dataset to analyse wind power potential in Turkey In Murat’s study and Cumali’s study, the datasets were used in research on energy potential only for one year (2004 and 2011), respectively Keyhani et al (2010) used data between 1995 and 2005 to evaluate wind energy potential in Tehran where is the capital of Iran In Malaysia, wind energy potential was assessed thought using data that was collected at ten meteorological stations for ten years (Sopian, Othman, & Wirsat, 1995) Onshore and offshore wind energy in Morocco has been analysed using Weibull distributions to describe wind performances (Nfaoui, Buret, & Sayigh, 1998; Allouhi, et al., 2017) Wind energy potential for power generation of Maiduguri and Potiskum in Nigeria was investigated by Fagbenle et al (2011) Measure data is also using to analyse wind

characteristic and the wind energy potential in Egypt (Mayhoub & Azzam, 1997; Ahmed, 2010) The wind speed, the wind rose, energy rose, energy density and air density in a south-western sea area of Korea were studied by Oh et al (2012) The wind characteristic and wind energy generation in Jordan was assessed base on statistical analysis (Bataineh & Dalalah, 2013) According to Sultan et al (2010), the determination of the potential location to wind power applications in Oman has been analysed based on hourly wind data during five-year All of the above studies use data obtained from satellites and measuring stations to assess wind energy potential

It can see that the use of wind data from measurements and observations to assess wind energy potential is highly reliable

The major challenges to national marine authorities and the government are how to manage the planning, consenting, installation and operation of offshore wind projects and integrate those activities effectively into strategies and other activities such as ports or harbour restrictions, fishing, shipping, military/aviation and natural/cultural heritage site designations (Dinh & McKeogh, 2018) In this context, Marine Spatial Planning (MSP) is a new way of looking at how we use the marine area and planning how best to use it into the future (Marine Spatial Planning: Methodologies, Environmental Issues and Current Trends) MSP play an important role in managing marine interactions and benefits effectively Indeed, it has showed significant results

in the stability of human activities as well as the sustainability of reaction between stakeholders (Dinh & McKeogh, 2018) (Ehler, Zaucha, & Gee, 2019)

The increasing uses and users of the ocean leads to increasing conflict Studies that sought to reduce these conflicts have shown the benefits of zoning the ocean in space and time (Ehler et al., 2019) They demonstrated that a planned use of the marine environment can minimise losses and maximise gains for conflicting sectors (White, Halpern, & Kappel, 2012) MSP has therefore been developed from its initial conceptualization as a zoning tool for marine conservation to a multi-dimensional approach to spatial marine governance (Ehler et al., 2019) Based on the evaluation

of spatial and temporal variation of offshore wind potential, this paper proposes

zoning of offshore wind resources in Vietnam, as a very initial attempt to kick start the development of MSP in the country sea territory The beneficial approach of time and space zoning discussed in (Ehler et al., 2019) is introduced in this study, where the zoned resources are made adaptive to the lessons learned from the Great Barrier Reef Marine Park (GBRMP) (Day, 2002) and the ongoing MSP development in Europe and other countries

2.2 Wind energy research situation in Vietnam

In Vietnam, the exploitation and application of renewable energy sources are important to cope with the rapidly growing energy demand of the country The country is likely to have a very huge opportunity for developing offshore wind energy (Luong, 2015) because of more than 3,000 km long coastline and one million square kilometer sea area However, the number of studies on this issue are still limited The use of geographical information system to assess the potential of wind energy on land

in Vietnam has been implemented by Nguyen (2007) Tan et al (2012) used hourly data collected in 8 cities to assess the wind power potential in each area In (Tran & Chen, 2016), the wind energy resources on Phu Quoc island was investigated base on daily data that are collected between 2005 and 2011 The results of the study show that wind energy from the northwest accounts for more than 35% of the total wind energy on the Phu Quoc island Doan et al (2018) carried out research on offshore wind energy in Vietnam using a numerical simulation model However, like many other developing countries, the assessment of this resource reserve in Vietnam has not been conducted widely In this review, current research status, the number of studies on wind energy potential, especially offshore wind energy in Vietnam is still limited Therefore, the implementation of this thesis is very necessary It will be a useful document for planners and investors

CHAPTER 3 METHODOLOGY OF RESEARCH

3.1 Methodology

Figure 3.1 Methodology flowchart of the study Figure 3.1 shows methodology flowchart of this thesis The first step in this study is the comparison of surface wind speed probability distribution between CCMP data and measurement data at seven meteorological stations along the coast and islands After the comparison shows that CCMP data is suitable for use, the next step is to

CCMP data (wind surface)

Validation (comparing wind speed probability distribution)

Extrapolate wind speed at 100m

Using LEANWIND model

Calculate wind energy, capacity factor, power distribution for zones

Zoning the offshore wind

resource

Measurement data at 7 meteorological stations

extrapolate the wind speed at different heights and evaluate the spatial and temporal variation of wind speed and direction The division of regions was then carried out based on the characteristics of each region This research was divided into 4 regions for study Offshore wind energy resources of each zone are evaluated based on the demand and characteristics of each region In this study, LEANWIND is assumed to

be used in wind farms Wind energy, capacity factor, and power distribution were calculated based on the parameters of the turbine and wind speed at 100m

3.2 CCMP dataset

The surface wind dataset is used in research that obtained from the Cross-Calibrated Multi-Platform (CCMP) project published by the U.S National Aeronautics and Space Administration (NASA) (NASA/GSFC/NOAA, 2009) (Atlas, et al., 2011) This project aimed to obtain multi-instrument ocean surface wind velocity which is used to analysis meteorology and oceanography This dataset is built from combining cross-calibrated satellite winds from Remote Sensing Systems by using a Variational Analysis (VA) Method (Atlas, et al., 2011) This method creates a gridded surface wind analysis with a high spatial resolution (0.25 degree) that can minimize the deviation of data The cross-calibrated satellite winds data of the CCMP dataset obtained from a number of microwave satellite instruments The microwave radiometers such as Special Sensor Microwave Imager Sounder (SSMIS) and WindSat (Gaiser, et al., 2004) were used to receive information about wind speed The microwave scatterometers such as QuikScat and SeaWinds were also applied to obtain wind speed and directions by developing a geophysical model function Wind velocity is observed and analysed at 10 meters high The spatial resolution of dataset

is 0.25-degree (latitude) x 0.25-degree (longitude) The spatial of CCMP is higher than some other such as Modern-Era Retrospective analysis for Research and Applications (MERRA) data (Rienecker, et al., 2011; Gelaro, et al., 2017), Climate Forecast System Reanalysis (CFSR) data (Saha, et al., 2010) with spatial resolution of 0.5 degree and 0.625 degree The temporal resolution of CCMP is also better than some common dataset like QuikSCAT data (NASA, 2012), Aquarius dataset (NASA Aquarius project, 2017) with a temporal resolution of 1 month and 3 months, respectively The CCMP dataset has a high

temporal resolution of 6 hours and the timespan of the dataset is 25 years, from 02 July 1987

to 31 December 2011, as listed in Table 3.1 The two main factors that are considered to choose data are spatial resolution and temporal resolution, both of which are high in CCMP dataset Hence, this study decided to choose CCMD data for use in research Because the entire CCMP data for 25 years is very large, this research decided to use wind data for the last five years of the dataset (from 2007 to 2011)

Table 3.1 Information of the CCMP dataset (NASA/GSFC/NOAA, 2009)

Northernmost latitude (degree) 78

Southernmost latitude (degree) -78

Westernmost longitude (degree) 0

Easternmost longitude (degree) 360

Spatial resolution (Latitude x Longitude) 0.25 degrees x 0.25 degrees

The CCMP dataset is then validated by comparing with the observed data of several meteorological stations located in Vietnam The temporal resolution of measurement data for comparison with CCMP data is 6 hours similar to the temporal resolution of CCMP data The measuring stations are also placed at a height of 10m above sea level Thus, the information about the height of the two wind datasets is very similar

to each other This paper has compared surface wind speed probability distribution between CCMP data and measurement data at seven meteorological stations along the coast and islands for 5 years (from 2007 to 2011)

3.3 Zoning the offshore wind resources

Based on the beneficial approach of time and space zoning discussed by Ehler et al (2019) and the lessons learned from the Great Barrier Reef Marine Park (GBRMP) (Day, 2002) and from the ongoing MSP development in Europe and other countries (Ehler et al., 2019), the following set of criteria is proposed to initially zone the offshore wind resources in Vietnam

a Sea area of 100 nautical miles (185.2 km) far from the coastline and the long coastline of Vietnam need to be considered

b The temporal variation in temperature over the year, which relates to the coastal and marine biology and human activities at sea including fishing

c Synchronous power sources (hydropower plants, gas/oil-fired power plants), major electricity transmission lines (500 kV, 220 kV) and major natural gas source and infrastructures

d Location or the potential of major sea ports and container terminals that may be suitable to the assembly, transportation, and installation of offshore wind turbines components

The distance of 100 nautical miles from the coastline is selected in criterion (a) as it

is the maximum distance that offshore wind farm can be deployed in the future at economical costs The temperature of the seas in criterion (b) will affect the characteristics of aquaculture in each region Therefore, zone division based on temperature is necessary Figure 3.2 reveals existing synchronous power sources and major transmission lines in Vietnam as discussed in criterion (c) The continental in the north of the country is a large area where there are diverse sources of energy The northern border provinces import electricity from China The eastern provinces use energy from coal-fired power plants Hydropower is the main supply of energy for the remaining provinces in the region The continental shape of the northern central region is long and narrow The energy sources in this area are from two main sources (hydropower and import electricity from Lao) Because the region has few energy sources, the government has invested 500 kV lines along the area to provide

electricity for the people The main energy source in the mainland along southern central region is from hydropower In order to enhance the transmission of electricity

to this area, some 200 kV and 500 kV lines have been installed here Energy from the gas/oil-fired power plant is the main source of energy for life in the southern region

of Vietnam A part of the energy from that source has been exported to Cambodia

Figure 3.2 Major synchronous power sources and power transmission lines in

Vietnam (EREA, 2019)

It can also be seen that the regional division based on the location of the seaports and container terminals discussed in criteria (d) is essential They are the key elements of the supply chain required for assembly, transportation, and installation of offshore wind turbines components including blades, towers, substructure and foundations (Dinh & McKeogh, 2018) In order to accommodate installation vessels, offshore developers require a port draft of up to 10 meters, quayside of up to 300 meters and

water way of up to 200 meters (Akbari, 2015) The transportation of monopiles using heavy lift cargo vessels and their installation by jack-up vessels require drafts about 9.5 m and 5.8 m to Chart Datum of water, respectively (Elkinton, Blatiak, & Ameen, 2014) The overall lengths for heavy lift cargo vessels are approaching 170 m (Elkinton et al., 2014) Figure 3.3 shows that there are a number of major sea ports and container terminals in the southern central region and the southern region of the country

Figure 3.3 Location of major ports and container terminals in Vietnam (data source: (SeaRates), (VPA), some in-land river ports accessible to large vessels)

Because when choosing the location of the wind farms, the government will need to consider its impact on the economy of each region The results of the study will be

an important document to help the potential investors and offshore wind farm developers to choose the most appropriate investment location where are potential for exploiting offshore wind energy in each zone

Figure 3.4 Four zones are considered in the study Based on the four criteria discussed above, offshore wind resources in Vietnam have been classified into four zones with boundary shown in Figure 3.4 Zone 1 is the place with the coldest winter in the four zones Zone 1 includes 8 coastal provinces from Quang Ninh province to Ha Tinh province Zone sea 2 has a moderately cold winter Zone 2 includes 7 coastal provinces from Quang Binh province to Binh Dinh province Zone 3 is less affected by the winter monsoon Zone 3 includes 5 coastal provinces from Phu Yen province to Ba Ria – Vung Tau province Zone 4 is the region with the highest temperature in the year because it is least affected by the winter Zone 4

includes 8 coastal provinces from Ho Chi Minh city to Kien Giang province The results of the study will be an important document to help investors choose the most appropriate investment location where are potential for exploring offshore wind power in each zone

3.4 Estimation of wind energy potential

In order to accurately assess wind energy potential relevant to the wind turbines, the information on the wind at different heights is required The CCMP dataset used in this research contains wind speed at 10 meters in height The wind power law in Equation (1) that has been used for extrapolating wind speed from the sea surface to specific heights (Allouhi, et al., 2017; Dabbaghiyan, Fazelpour, Abnavi, & Rosen, 2016; Soulouknga, Doka, Revanna, Djongyang, & Kofane, 2018) is adopted

𝑣2 = 𝑣1(𝑧2

In which, the parameter 𝛼 is the power law exponent, 𝑣1is wind speed at the height

𝑧1 and 𝑣2 is wind speed at hub height 𝑧2 According to Davenport (1965) and Hsu (1992), the magnitude of the power law exponent was found to be approximately 0.1 with the natural conditions in the sea

Wind turbines converse the kinetic energy of wind into electrical energy By operation classification, there are two basic types of wind turbines: vertical axis and horizontal axis where the horizontal axis wind turbines are more popular than the vertical axis one The power output of a horizontal axis wind turbine is calculated following Equation (2) (Teyabeen, Akkari, & Jwaid, 2017; Carrillo, Montaño, Cidrás,

𝑃𝑓(𝑣) =1

In Equations (2) and (3), the electric power generated by the wind turbine is 𝑃(𝑣)

The parameters P r , v i , v r , v o and A are the rated power, cut-in wind speed, rated wind

speed, cut-out wind speed, and rotor swept area of the wind turbine 𝑃𝑓(𝑣) is the nonlinear relationship between wind speed and electric power In Eq (3), 𝜌 is the air density and 𝐶𝑝 is the power curve coefficient

The energy conversion output of a wind turbine over a time period can be determined

Where 𝑁𝑡 is the number of wind turbines in the wind farm

The capacity factor (CF) represents the ratio between the actual electrical energy

output and the maximum possible electrical energy during the time period and depends on both wind turbines and the site characteristics The annual CF is defined as:

𝐶𝐹 = 𝐸𝑜𝑢𝑡

Where the annual maximum possible electrical energy is:

CHAPTER 4 RESULTS AND DISCUSSION

on the 5-year wind speed data of both measurement data and the CCMP data A glance at the two graphs in each Figure provided reveals the similarity of two data sources is very high From five Figures, we can visible that the shape of the wind speed probability distribution graph from two data sources very close together At Hon Ngu and Ly Son stations, the results are almost identical In addition, at Phu Quy island, the probability of distribution of wind speed in the range of 10 m / s is the largest compared to 6 other stations Phu Quy is the administrative territory of Binh Thuan province After comparing CCMP data with measured data at stations, it can prove that CCMP data is very close to reality and is perfectly suitable for research use With high spatial resolution (0.25 × 0.25) and temporal resolution (6 hours) of CCMP datasets, the use of CCMP data to evaluate offshore wind energy potential is completely reliable