Public Disclosure Authorized Public Disclosure Authorized Public Disclosure Authorized Public Disclosure Authorized JULY 2015 Wind Resource Mapping in the Maldives CANDIDATE SITE IDENTIFICATION REPORT This report was prepared by DNV GL, under contract to The World Bank. It is one of several outputs from the wind Resource Mapping and Geospatial Planning Maldives [Project ID: P146018]. This activity is funded and supported by the Energy Sector Management Assistance Program (ESMAP), a multi-donor trust fund administered by The World Bank, under a global initiative on Renewable Energy Resource Mapping. Further details on the initiative can be obtained from the ESMAP website. This document is an interim output from the above-mentioned project. Users are strongly advised to exercise caution when utilizing the information and data contained, as this has not been subject to full peer review. The final, validated, peer reviewed output from this project will be the Maldives Wind Atlas, which will be published once the project is completed. Copyright © 2015 International Bank for Reconstruction and Development / THE WORLD BANK Washington DC 20433 Telephone: +1-202-473-1000 Internet: www.worldbank.org This work is a product of the consultants listed, and not of World Bank staff. The findings, interpretations, and conclusions expressed in this work do not necessarily reflect the views of The World Bank, its Board of Executive Directors, or the governments they represent. The World Bank does not guarantee the accuracy of the data included in this work and accept no responsibility for any consequence of their use. The boundaries, colors, denominations, and other information shown on any map in this work do not imply any judgment on the part of The World Bank concerning the legal status of any territory or the endorsement or acceptance of such boundaries. The material in this work is subject to copyright. Because The World Bank encourages dissemination of its knowledge, this work may be reproduced, in whole or in part, for non-commercial purposes as long as full attribution to this work is given. Any queries on rights and licenses, including subsidiary rights, should be addressed to World Bank Publications, The World Bank Group, 1818 H Street NW, Washington, DC 20433, USA; fax: +1-202-522-2625; e-mail: pubrights@worldbank.org. Furthermore, the ESMAP Program Manager would appreciate receiving a copy of the publication that uses this publication for its source sent in care of the address above, or to esmap@worldbank.org. RENEWABLE ENERGY WIND MAPPING FOR THE MALDIVES Candidate Site Identification Report The World Bank Document No.: 702909-AUME-R02 Issue: C, Status: FINAL Date: 02 July 2015 IMPORTANT NOTICE AND DISCLAIMER 1. 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Except and to the extent that checking or verification of information or data is expressly agreed within the written scope of its services, DNV GL shall not be responsible in any way in connection with erroneous information or data provided to it by the Customer or any third party, or for the effects of any such erroneous information or data whether or not contained or referred to in this document. 5. Any energy forecasts estimates or predictions are subject to factors not all of which are within the scope of the probability and uncertainties contained or referred to in this document and nothing in this document guarantees any particular wind speed or energy output. KEY TO DOCUMENT CLASSIFICATION For disclosure only to named individuals within the Client’s Strictly Confidential : organisation. For disclosure only to individuals directly concerned with the Private and Confidential : subject matter of the document within the Client’s organisation. Commercial in Confidence : Not to be disclosed outside the Client’s organisation. DNV GL only : Not to be disclosed to non-DNV GL staff Distribution for information only at the discretion of the Client (subject to the above Important Notice and Disclaimer and the Client’s Discretion : terms of DNV GL’s written agreement with the Client). Available for information only to the general public (subject to Published : the above Important Notice and Disclaimer). DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 4 Project name: Renewable Energy Wind Mapping for the Maldives DNV GL – Energy Report title: Candidate Site Identification Report Renewables Advisory Customer: The World Bank, 9665 Chesapeake Drive, Suite 435 1818 H Street, N.W. San Diego, CA 92123 Washington, DC 20433 Tel: 703-795-8103 Contact person: Abdulaziz Faghi Enterprise No.: 94-3402236 Date of issue: 02 July 2015 Project No.: 702909 Document No.: 702909-AUME-R02 Issue/Status: C/FINAL Task and objective: Provide an overview of wind monitoring issues, site potentials and selection criteria. Provide a shortlist of candidate sites. Prepared by: Verified by: Approved by: Mark Purcell Trenton Gilbert Richard Whiting Engineer, Renewables Advisory Head of Section, Developer Support Service Line Leader, Project Development Services (Pacific), Renewables Advisory Graham White Craig Houston Senior Technical Adviser, Renewables Senior Advisor, Strategy & Policy Advisory Caroline Donohue GIS Analyst, Environmental and Permitting Services ☐ Strictly Confidential Keywords: ☐ Private and Confidential World Bank, ESMAP, ASTAE, Maldives, wind, ☐ Commercial in Confidence mesoscale, mapping, meteorological mast, site ☐ DNV GL only selection, GIS ☒ Client’s Discretion ☐ Published Reference to part of this report which may lead to misinterpretation is not permissible. Issue Date Reason for Issue Prepared by Verified by Approved by A 16 Feb 2015 DRAFT MP/GW/CD TG/CH RW B 04 May 2015 FINAL MP/GW/CD TG/CH RW C 02 July 2015 Final, repaginated MP/GW/CD TG/CH RW DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 5 Table of contents 1 INTRODUCTION .............................................................................................................. 7 1.1 Background 7 1.2 Project description 8 1.3 Project considerations 9 2 GENERAL APPRECIATION OF MALDIVES’ WIND RESOURCE ................................................ 11 3 MAST SITE IDENTIFICATION AND RANKING ..................................................................... 16 3.1 Methodology 16 3.2 Mapping of spatial features and constraints 17 3.3 Multi-criteria analysis 18 3.4 Site identification 26 4 MEASUREMENT MAST SPECIFICATIONS AND RECOMMENDATIONS ..................................... 31 4.1 Mast 31 4.2 Equipment 31 4.3 Other equipment 33 4.4 Measurement configuration 34 4.5 Documentation 38 5 REFERENCES ................................................................................................................ 40 APPENDIX A – DETAILED SITE SELECTION IMAGES ....................................................................... 41 DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 6 1 INTRODUCTION The results described in this report are derived from interim output and are preliminary and unvalidated, and they have not been subjected to full peer review. DNV GL does not guarantee the accuracy of the maps, data, and visualizations presented in this report, and accepts no responsibility whatsoever for any consequence of their use. Wind speed values shown in tables and maps should not be relied upon in an absolute sense. Rather they should be strictly interpreted as indicative (e.g., elevated windiness near mountaintops and escarpments). Users are strongly urged to exercise caution when using the information and data contained within this report. During Phase 2 of this project, measurements will be collected from a number of representative sites throughout the country over a 24 month period, and these will be used in Phase 3 to develop a final, validated, peer-reviewed suite of outputs from this project, which will be made available at the project’s completion. The World Bank (the “Client”) has retained Garrad Hassan America, Inc. (“DNV GL”) to provide a validated mesoscale wind atlas for the Maldives, including associated deliverables and wind energy development training courses. Validation of the wind atlas will be undertaken by installing several wind measurement meteorological masts throughout the country. Meteorological data collected at these sites over a 2-year period will provide the basis for validating the mesoscale modeling outputs. This report presents the initial findings of DNV GL’s investigation on appropriate wind measurement sites and will form the basis of further discussions with the World Bank and all relevant Maldivian stakeholders, including the Ministry of Environment and Energy. This report also provides general specifications and recommendations for the measurement equipment proposed. 1.1 Background The Maldives is in the early stages of exploring the resource potential of wind power. To date there are no utility scale wind turbines operating in the country. Single-purpose meteorological masts dedicated to the high quality measurement of wind resource have not been deployed extensively in the country, presenting a significant barrier to policymakers interested in evaluating the potential for supply diversity and distributed generation that wind energy projects can deliver. The Maldives does not possess any native, non-renewable energy resources (oil, natural gas, coal) and therefore relies heavily on the importation of fuels to provide power generation, transportation, lighting and food preparation. Diesel is the dominant fuel source which provides all of the electricity generation, fishing fleet, and sea transport. Aviation fuel is another major import. To decrease the dependency on imported fuels, the Maldives Government is planning to transform the energy sector with a target of achieving carbon neutrality. The Maldives has good prospects for solar and wind energy, but these resources have not been extensively measured or exploited for any significant electricity generation to date. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 7 1.2 Project description The key goal of this project is to provide Maldives’ policy makers and stakeholders with accurate and valuable knowledge of the national wind resource which can be of direct practical use, both for formulating energy policy and implementing wind projects. The transfer of practical knowledge through the installation and operation of high quality wind measurement equipment will also strengthen local capacity to support future development of wind projects in the Maldives. The primary deliverable supporting the above goal will be a well-validated national mesoscale wind resource atlas that will greatly improve the awareness and understanding of the locations with the greatest potential for wind energy. When used in combination with a Geographic Information System (GIS), this forms a highly valuable planning tool which facilitates energy strategy planning for policy makers and stimulates commercial wind development by removing an important knowledge barrier. This Site Identification Study focuses on the identification of suitable measurement locations to support the validation of the preliminary mesoscale wind atlas and should be viewed together with the Mesoscale Wind Modeling Report #1 [1]. Under Phase 2 of this project, wind monitoring will be carried out at multiple locations across the country for the purpose of validating the initial Phase 1 mesoscale mapping outputs described in [1]. In order to serve this purpose effectively, the identified measurement locations must capture the different large-scale wind characteristics of the country; inform and improve the wind modeling in areas of uncertainty; and capture a sufficient spectrum of ground conditions represented in the four- dimensional atmospheric wind model. In addition to these technical requirements, a host of other practical issues such as site accessibility, land availability, vegetation sheltering, exclusion zones and environmental constraints have been considered in the selection of the potential mast locations. DNV GL has also analyzed factors including distance to load centers and wind speed which are important for future development of wind energy. These have been included so that masts may support the goal of validating the wind atlas, as well as supporting future development in areas with high potential for exploitation of the wind resource. Section 3 explains in detail the multi-criteria methodology used to incorporate all of these important factors relevant to the selection of mast locations. DNV GL hopes that the Ministry of Environment and Energy and other relevant agencies will be actively involved in the selection process, help review the inputs and provide the local knowledge needed to ensure a successful measurement campaign with lasting value for the Maldives. DNV GL has identified a preliminary list of 42 promising sites for wind measurement masts in the Maldives. At least 4 locations will be shortlisted after consultation with the Ministry of Environment and Energy, the World Bank and other relevant stakeholders. Once an agreement is reached, site visits to the shortlisted locations will be performed. Based on the site visits, a final group of 4 to 5 sites will be selected and appropriately instrumented monitoring equipment will be deployed to validate the mesoscale wind atlas. The number of monitoring sites selected will be dependent on the ability to reuse suitable existing towers that may currently be installed throughout the country. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 8 1.3 Project considerations There are a number of considerations regarding the identification of sites for Phase 2 of the project, including: • The Terms of Reference (TOR) [2] for the project specify a requirement for four 80 m meteorological masts. • The country is quite linear with 1200 islands spread over a vast area stretching 860 km north to south and about 100 km east to west as seen in Figure 1-1. • None of the islands rise more than 3 m above sea level and thus there is no significant topographical enhancement of the winds in the region. • Land is scarce as most inhabited islands are fully developed or utilized and as a result it may be difficult to erect a guyed mast on many of the inhabited islands. • Approximately 180 populated islands have independent electricity supplies, with no island interconnections. • The Greater Male Region has the largest electrical load (approximately 225 GWh/annum) and therefore the greatest potential for diesel substitution. Consideration is being given to a plan to connect some islands in the Greater Male Region with a high-voltage (HV) interconnection [3]. • There are approximately 20 islands with electricity consumption of 2 GWh per annum or greater. • There are a number of suitable existing masts throughout the country that may be available to mount wind monitoring instruments upon, including: o The telecom company Dhiraagu has one guyed telecommunications mast which could possibly be used for wind measurements. o There is currently a wind monitoring project sponsored by the Bilateral Japan-Maldives Joint Credit Mechanism (JCM) which plans to install wind monitoring equipment at three locations with 40-50 m met masts. Data may be available from this program of work which could augment the program. o XEMC, a Chinese company, installed two SODAR remote sensing systems on two islands north of Male (Thulusdhoo and Dhiffushi). These two devices are no longer in operation but are still in the country and could possibly be re-commissioned for wind measurements. o Suzlon installed an 80 m met mast and instrumentation on Addu Atoll (Hithadhoo). While the mast is still in-situ, the instrumentation has been removed. FENAKA owns this asset and they have confirmed that new instrumentation could be installed, however all guy wires would need to be renewed. o An 80 m met mast and instrumentation has been installed on Gaafaru island in Kaafu Atoll. It is understood that the Gaafaru Island Council owns this asset and it may be possible to install new instrumentation and refurbish the mast, however all guy wires would need to be renewed. • The availability of sites which are both practicable and technically desirable from a model validation perspective will need to be balanced with the need to obtain sufficient geographical coverage of the country. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 9 Figure 1-1 Base map of the Maldives including designated study area DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 10 2 GENERAL APPRECIATION OF MALDIVES’ WIND RESOURCE The Mesoscale mapping report [1] is a key Phase 1 deliverable of this ESMAP project and it provides the most accurate picture of the wind resource in the Maldives currently available. This map will be further improved by validating the modeling results with high quality measurements to be recorded over 2 years at the selected measurement locations. Before a detailed multi-criteria analysis can be undertaken to identify promising locations for installing measurement masts, it is essential to understand the characteristics of the wind conditions in the Maldives and how these vary across the country. Figure 2-1 and Figure 2-2 show preliminary mesoscale annual mean wind speed map at 100 m and 10 m above ground level respectively, based on the full 10-year simulations performed with the DNV GL Wind Mapping System (WMS). These results provide, for the first time, a detailed picture of the long-term wind resource across the country. Figure 2-3 demonstrates the mesoscale modeling uncertainty index which provides further insight to the modeling of the wind resource. From the Phase 1 analysis, a number of interesting features of the wind climate in the Maldives appear, and are discussed below. Geographical variation The Maldives stretch approximately 860 km between about 7.1° North to 0.7° South. The northern most atoll lies 500 km from the southern tip of India. The Palk Strait between India and Sri Lanka is a significant wind corridor where the flow of air is channeled between the two land masses. This geographical enhancement leads to strong mean wind speeds (about 10 m/s) at the narrowest part of the strait. This acceleration occurs during both the northeast and southwest monsoons, and the effect extends to northern and central parts of the Maldives. It is clear that the best wind resource lies mainly in the northern section of the country. Lower mean wind speeds prevail within the equatorial zone which is often typified by light and variable conditions termed the “doldrums”. Monsoons The climate within the Maldives regions is influenced by two distinct monsoons: • Northeast monsoon (Iruvai) occurring from January to March; • Southwest monsoon (Hulhangu) occurring from May to November. The months of April and December are ”transition months” between the two dominant phases of the monsoon. Iruvai is typified by dry conditions and clear skies, while Hulhangu ushers in the wet season. The Hulhangu monsoon is generally accompanied by rough seas and strong winds. Topographical The Maldives are situated within the Indian Ocean, southwest of the southern-most tip of India, and the entire country sits effectively at sea level. Thus, there is no significant topographical enhancement of the winds in this region, as most islands rise less than 1 m above sea level, and only few have elevations approaching 3 m above sea level. While the majority of islands occupy a land area smaller than 0.5 km2, a few atolls have a total land area as large as 20 km2. Impacts of vegetation and urban areas Many islands are comprised of fairly dense vegetation, or patches of vegetation which impart increased frictional drag on the near surface wind. There are also several islands which are completely urbanized. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 11 This creates increased drag on the near-surface wind speeds relative to the surrounding water points, and this effect is most evident in the 10 m and 50 m above ground level (AGL) preliminary mesoscale wind speed maps. The impacts of surface friction gradually reduce with height and are less evident in the wind speed maps for heights above 50 m. It is noted that thermally driven land/sea winds are not expected to have a significant impact on the wind regime in the Maldives, due to the relatively small size of most land areas. Variation of wind speed with height The variation of wind speed with height over the study area is consistent with that which would be encountered in an area that is predominantly ocean. This includes small variations in wind speed with height over most of the study area (with typical reductions of approximately 10 % between 100 m and 10 m), but more substantial variations in those areas denoted as land (with typical reductions of 20 to 30 % between 100 m and 10 m). Area for detailed study In coordination with The World Bank, DNV GL has restricted the extent of the study area to approximately 25 km from any landmass within the Maldives. This covers the territorial waters of the country (12 nautical miles from the coastline by definition, or approximately 22.2 km). The rationale is to exclude areas where development is not feasible, since the sea floor drops sharply to several thousand meters in all directions from the atolls. The selected study area is shown by the dashed line in Figure 1-1. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 12 Figure 2-1 Preliminary and unvalidated mesoscale annual mean wind speed map at 100 m AGL created with the DNV GL Wind Mapping System DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 13 Figure 2-2 Preliminary and unvalidated mesoscale annual mean wind speed map at 10 m AGL created with the DNV GL Wind Mapping System DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 14 Figure 2-3 Preliminary and unvalidated mesoscale wind speed uncertainty index at 100 m AGL created with the DNV GL Wind Mapping System DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 15 3 MAST SITE IDENTIFICATION AND RANKING 3.1 Methodology The preliminary selection of the most suitable locations for installing monitoring equipment for the purpose of validating the mesoscale modelling results has been conducted using a multi-criteria analysis specifically tailored to the project objectives and the Maldives. The main objectives were to select sites which provide the maximum potential for improving the accuracy of the mesoscale mapping and also sites which show potential for future wind development, while reducing potential development risks. Practical factors such as ease of installation and maintenance, and minimizing environmental and social impacts have also been considered in the selection process. The methodological approach can be summarized in seven main steps: 1. The provided spatial constraints were mapped (e.g., environmentally sensitive areas, population centers and resorts). 2. The central point of the landmass of each individual island, as outlined by the Land and Survey Authority of the Maldives, was digitized. Where large islands spanned a significant distance, additional points were added to represent the extremities of these land masses. Note that these points were not intended to represent actual mast locations, but were to be used for purpose of the multi-criteria analysis. 3. Each of these points were assessed and a score assigned for the criteria under consideration (e.g., wind resource, wind uncertainty, proximity to resorts, proximity to environmentally sensitive areas and proximity to inhabited islands considering both their electrical load generation and population). Further explanation of the criteria considered can be found in Section 3.3. 4. The weighted sum of the scores associated with the criteria was used to identify promising islands in suitable locations that provided coverage of the geographical extent of the Maldives. 5. These promising islands were then individually assessed considering additional criteria that would influence their suitability for the installation of wind monitoring masts (e.g., land suitable for construction, clear of obstacles in the predominant wind directions, proximity to airports and harbors). 6. A long-list of the most suitable sites was identified; and 7. Preferred regions and a subset of preferred sites were established. The above approach is described in greater detail in the following sections and summarized in Figure 3-1. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 16 Location of environmentally Centroid point of each island Location of populated islands Location of resorts sensitive areas Assess and rank each point for Assess each point for proximity wind speed and wind to constraints uncertainty Key Identify high-scoring points with desired geographical Inputs coverage Analysis Assess high-scoring points for other constraints Establish site long-list, and preferred regions/sites Figure 3-1 Methodological approach 3.2 Mapping of spatial features and constraints DNV GL used GIS topographical data provided by the Ministry of Environment and Energy and readily accessible mapping data and other documentation available in the public domain to prepare detailed maps showing land areas, environmentally sensitive areas, generation and population centers and other key inputs deemed of relevance in identifying site locations. The primary data sources are the following: • DNV GL preliminary mesoscale wind map (Figure 2-1), uncertainty index map (Figure 2-3) and roughness map [1]; • GIS data from Maldives Land and Survey Authority including: o Administrative areas containing coastline of each island within the Maldives (Figure 1-1); o Inhabited islands population, generation capacity and energy consumption database (Figure 3-2); • Resort island database (Figure 3-3); • Environmentally Sensitive Areas register from the Environmental Protection Agency, Maldives [4] (Figure 3-4); • IATA Airport database (Figure 3-3); • Google Earth; Presented within the body of this report and Appendix A are a complete set of maps showing the above GIS data as well as primary outputs of the Mesoscale Wind Modeling Report 1 [1]. DNV GL notes that while the above list covers a wide range of inputs, it is not exhaustive, and the data for each feature may not be entirely up-to-date or complete. Therefore DNV GL would welcome feedback DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 17 from any relevant agency to assist in validating the data used as the basis for this preliminary GIS site selection process. Additionally, the following data was not available for this initial assessment and may have significant impact on the site identification study: • Official Land tenure information and possible issues related to ownership; • Military and other government-related exclusion zones; • Detailed local security considerations. Any further guidance on obtaining these and any other relevant data would be welcomed. 3.3 Multi-criteria analysis A site scoring map showing the relative appropriateness for wind monitoring locations across the study area has been created and is supplied in Figure 3-5. A color scale indicates the scoring results, which provide an indication of the suitability of each island for wind monitoring. The following section details the methodology used to derive this map. 3.3.1 Multi-criteria analysis of available area Locating the best sites among the limited land in the Maldives is achieved by using a multi-criteria analysis which involves considering a set of factors that will be used to produce a Site Scoring Map. The center point of each individual island was identified based on data supplied by the Land and Survey Authority, and a score was calculated for each island center point based on the criteria considered, and the factors representing those criteria. The main objectives for identifying candidate monitoring locations were to find locations that: • were suitable for validating the mesoscale wind map; • considered technical, social and environmental constraints; and • were in areas deemed suitable for future wind development. Consideration of these objectives was achieved by allocating appropriate scores based on key criteria and associated factors for site selection. A relative weight was then attributed to each criterion. This is detailed in Table 3-1. Table 3-1 Relative weighting of key criteria Relative Criteria Factors Weight [%] Wind resource a) Mean wind speed 10 Area of optimal validation value b) Wind uncertainty index 10 c) Distance to load/population centers Area suitable for future wind d) Size of load centers 40 development e) Size of population centers Planning issues f) Proximity to resorts 20 Environmental sensitivity g) Proximity to environmentally sensitive areas 20 The relative weight of each factor in Table 3-1, and assigned scores, were derived based on DNV GL’s expertise in mesoscale wind mapping, wind energy development and mast installation. This is an area of potential discussion with stakeholders. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 18 The criteria, associated factors, and assigned scores are discussed below. Wind resource One of the objectives of the monitoring campaign is to optimize the validation of the mesoscale modelling results and ensure highest accuracy of the overall wind atlas. This will be of importance where the wind resource is highest. The key factor to capture this criterion is the predicted long-term mean hub-height wind speed. Mean wind speed at a height of 100 m AGL, as seen in Figure 2-1 from the work presented in [1], is used to represent the long-term hub height wind speed. A score of 0 is given to the lowest mean wind speed and a score of 10 is given to the highest mean wind speed modelled across each of the islands. This criterion has been assigned a relative weight of 10% of the total multi-criteria site score. Area of optimal validation value In order to validate the mesoscale wind map it is beneficial to measure wind speed in regions of higher modelling uncertainty. To incorporate this criterion, the factor considered is the preliminary uncertainty index map, produced as part of the initial mesoscale mapping work. The preliminary uncertainty index is initially set to be equal to the standard deviation of the outputs from the ten multi-physics multi-reanalysis mesoscale ensemble members as described in [1] and seen in Figure 2-3. Areas with a high index value, and therefore high standard deviation indicate an area where there is a lack of consensus between the ten multi-physics multi-reanalysis ensemble members, and shows the apparently increased difficulty in modeling the flows in these areas. A score of 0 to 10 is scaled to the range of preliminary uncertainty index from the analysis. As an example, a score of 0 would be given to the island with the lowest index value resulting from the analysis, while a score of 10 would be given to the island with the highest index value. This criterion has been assigned a relative weight of 10% of the total multi-criteria site score. Areas suitable to future commercial wind development The use of the measurements to support future wind energy developments is also foreseen as a valuable outcome. To capture this criterion, three factors which contribute to the suitability of areas for wind energy development have been considered, as listed below: (i) The distance to of the nearest load/population centers; (ii) Electricity consumption of the load center [GWh/annum]; (iii) Size of the population center. Other factors impact the assessment of future development potential, such as wind speed, land availability or environmental sensitivity; however, these are generally captured in the other mast siting criteria. The size and location of load and population centers are displayed in Figure 3-2 and in Appendix A. Areas in close proximity to large load centers are deemed desirable as they represent the greatest opportunity to offset diesel consumption. The annual electricity consumption of these load centers is likely to be proportional to a potential wind energy development’s realizable capacity. However, it is noted that installation of monitoring masts in urban areas may be undesirable due to space constraints, and visual impacts. In addition, installation of large scale wind energy facilities in areas too close to permanent residences can introduce environmental disturbances such as noise from the construction and operation of a wind farm as well as potential shadow flicker and electromagnetic interference impacts. DNV GL has implemented a score associated with these factors that aims to consider both the advantages and DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 19 disadvantages to siting the potential commercial wind development or monitoring masts within proximity of inhabited islands. Resorts It is considered that the installation of monitoring masts, and potentially wind turbines, in close proximity to tourist resorts may not be acceptable to resort operators, due to potential visual impacts and difficulties with land access. As such, islands at a greater distance from resorts have been allocated a high score. DNV GL has been supplied with a dataset containing the location and name of 108 resorts which are included in Figure 3-3 and in Appendix A. However, DNV GL notes that the dataset provided may not be complete and requests further input from relevant stakeholders to ensure more complete understanding of this potential constraint. Environmentally Sensitivity Areas DNV GL has been supplied with a set of Environmentally Sensitive Areas (ESA) totaling 282 points spread across the Maldives, as seen in Figure 3-4 and in Appendix A. These points indicate areas of particular environmental value ranging from the intended protection of mangrove and wetland areas, bird roosting areas as well as significant coral, fish, shark and turtle populations. A number of these points have descriptions indicating that the ESA covers the whole or a part of an island or reef, but this information is not provided for every ESA. As such, DNV GL has assumed the point location provided represents the center of the sensitive area. It should be noted however, the documentation accompanying the ESA list [4] states; ‘Please note that the areas identified in the ESA are not protected areas. A site/habitat being identified as an ESA does not indicate that sustainable development cannot take place. It encourages development to take place, taking into consideration the conservation of the sensitive area, thereby mitigating the negative impacts. Please note that ESA cannot be used as a reason for refusing sustainable development applications.’ Regardless, it is considered that installation of wind turbines or monitoring masts may be more challenging, or inappropriate, in or near some ESAs. Therefore, DNV GL has allocated a higher score to islands that are a greater distance from ESAs. Combined multi-criteria site scoring map Every island within the Maldives was assigned a score for each criteria, which was then weighted according to the weights in Table 3-1. The result is an initial multi-criteria site scoring map, which is shown in Figure 3-5 and in Appendix A. The purpose of this map is to present in a usable format the results of the multi-criteria analysis across the entire country, taking into account all weighting criteria simultaneously. In general, scores of 5 to 6 out of 10 (green areas) represent areas that are deemed more suitable for the installation of meteorological masts for the purpose of validating the mesoscale modelling results. The site scoring map will serve as the primary tool for selecting the short-list of final mast locations and DNV GL looks forward to participating in an open and inclusive selection process involving all relevant parties. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 20 [MWh/annum] Figure 3-2 Populated islands within the Maldives and their average electricity consumption DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 21 Figure 3-3 Listed resorts and airports within the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 22 Figure 3-4 Listed Environmentally Sensitive Areas within the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 23 Figure 3-5 Site scoring map for locating mesoscale wind validation masts DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 24 3.3.2 Additional criteria A number of additional criteria, which may have an impact on the suitability of a potential monitoring location, were either considered qualitatively during the identification of the long-list of potential sites, or will need to be considered as part of the process of establishing a short-list of potential sites. A number of these additional criteria are presented in Table 3-2. With the information made available to DNV GL at this stage, it has not been possible to evaluate all of these constraints for the selected potential monitoring sites. Further investigation of these criteria will be conducted during site visits and the final selection process, and will require discussion with the relevant Departments, Agencies and local stakeholders. Table 3-2 Additional criteria Criteria Factor Considerations Significant habitation, including buildings and infrastructure, may influence Urban Areas Influence on wind measurements. wind Vegetation - Trees Areas with dense trees may influence wind measurements. measurements Telecommunications Telecommunications towers may influence wind measurements Urban Areas Buildings and infrastructure, may preclude mast placement. Necessary to ensure that potential sites have sufficient land available at or Available land above sea level. Installation Islands without a harbor for transportation of mast equipment may not be Transport Complexity suitable. Vegetation - Trees Areas with dense trees may impede mast installation. Presence of telecommunications towers may improve mobile reception for Telecommunications data transfer. Airports Aviation restrictions may prohibit mast installation. Significant habitation may increase potential for visual impact or increase Urban areas difficulties with land access. Vegetation - Trees Areas with dense trees may impede mast installation. Telecommunication Potential interference to telecommunications systems may restrict mast towers placement. Planning Aviation Potential interference to aviation communications systems (e.g., Air Communication Surveillance Radar, Weather Radar, VORs) may restrict mast placement. Systems Environmentally ESA dataset represents ESAs as single points. Information on size of ESA or Sensitive Areas (ESAs) sensitivity to development may not be explicitly defined. Resort dataset may not be complete. Installation of masts or turbines near Resorts resorts may be unacceptable due to visual or other impacts. Operational Security Unsupervised masts may be vulnerable to vandalism at remote sites. Complexity Urban Areas Proximity to urban areas may simplify transport and logistics for servicing. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 25 3.4 Site identification Utilizing the Site Scoring Map seen in Figure 3-5, and the various input maps presented in Appendix A, DNV GL has proposed a long-list of 42 potential mast locations across the Maldives, offering good spatial coverage of the country. Aerial and satellite imagery was used to micro-site the locations. It shall be noted that the present identification was based on data supplied from Maldives’ government agencies, publicly available data and aerial imagery. Stakeholder engagement and local partner consultation will be required to identify the most suitable sites. A subsequent visit to shortlisted sites will aid in ensuring they are suitable and constructible. Additional micro-siting is expected during the site visits and potentially during the permitting process. The results are presented in the following table and figures: • The location of each potential site, along with scores allocated for each criterion, are shown in Table 3-3 (ordered from north to south); and • Figure 3-6 presents a map of the location of the proposed sites. As previously discussed under Section 3.2, official land tenure information was not available. It should be noted that the wind speed score presented in Table 3-3 does not represent the mean wind speed in meters per second. It is based on the score associated with wind speed, as discussed in Section 3.3.1. The objective and systematic multi-criteria analysis used by DNV GL is based on scores that are dependent on the accuracy of the GIS information. DNV GL has not performed any on-site validation or “ground-truthing” of features and cannot guarantee the accuracy of the information. Lastly, it should be noted that a different multi-criteria analysis method and weightings would likely lead to different results. The 42 sites identified have been selected based on a desire to satisfy the requirements of both the mesoscale validation process, and the various stakeholders that will need be involved in selecting the final monitoring locations. Thus, DNV GL is prepared to consider sites other than those proposed here provided that they satisfy the requirements of the mesoscale validation process. 3.4.1 Preferred regions Across the Maldives, 5 preferred regions have been highlighted, containing a number of sites from the long-list. The preferred regions can be seen in Table 3-3 and Figure 3-7. The preferred regions are intended to give good spatial coverage of the Maldives by ensuring measurements are taken throughout the length of the country in varying wind conditions, and also to provide measurements in high scoring regions. It is noted that 5 preferred regions have been identified, and it is expected that measurements will ideally be undertaken in at least 4 of the 5 preferred regions. The number of measurement locations will depend on the outcomes of discussions with stakeholders and the ability to re-use existing measurement equipment. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 26 Table 3-3 Preliminary long-list of proposed sites and scoring matrix – continued Area Suitable for Site Site Wind Area of Optimal Planning Environmental Future Wind Latitude Longitude Resource Validation Value Issues sensitivity Development Final Site Island Name Atoll Name Score ID (/10) Mean Wind Distance to and Proximity Proximity to Wind WGS84 WGS84 Speed Size of Load / to Resorts Environmentally Uncertainty Map datum datum Score Population Score Score Sensitive Areas Score (/10) (/10) (/10) (/10) Score (/10) Relative Weight  100% 10% 10% 40% 20% 20% 1 Thuraakunu 7.10470 72.89538 Ilhavandhippolhu 4.4 9.3 9.8 1.6 7.0 2.4 2 Kelaa 6.95241 73.21607 North Thiladhunmathee 4.7 8.8 8.4 1.7 7.5 3.9 3 Kun'burudhoo 6.66154 73.02634 South Thiladhunmathee 4.9 9.8 9.0 1.7 9.6 2.1 4 Kudamuraidhoo 6.64281 72.91556 South Thiladhunmathee 5.4 9.8 9.2 2.5 10.0 2.6 5 Vaikaramuraidhoo 6.54061 72.90123 South Thiladhunmathee 5.5 9.8 8.9 2.2 10.0 3.6 6 Maavaidhoo 6.51539 73.05735 South Thiladhunmathee 5.1 9.8 8.5 2.7 10.0 0.9 7 Innafushi 6.40917 72.64477 Maamakunudhoo 5.2 9.9 9.2 0.5 10.0 5.5 8 Bileiyfahi 6.33206 72.96831 North Miladhunmadulu 5.1 9.9 8.3 0.9 10.0 4.3 9 Hurasfaruhuraa 6.14011 73.03753 North Miladhunmadulu 5.2 9.8 7.8 1.8 9.0 4.6 10 Alifushi 5.96875 72.94879 North Maalhosmadulu 4.7 9.8 7.1 1.4 7.8 4.6 11 Gallaidhoo 5.96815 73.12393 North Miladhunmadulu 6.1 9.8 7.4 1.6 10.0 8.5 12 Vaadhoo 5.85271 72.99297 North Maalhosmadulu 6.1 9.8 7.0 2.5 9.6 7.5 13 Maanenfushi 5.75105 72.96107 North Maalhosmadulu 5.9 9.6 6.7 2.0 10.0 7.5 14 Velidhoo 5.66706 73.26895 South Miladhunmadulu 4.8 9.6 5.7 3.5 6.2 2.9 15 Kurehdhoo 5.64060 72.89460 North Maalhosmadulu 5.7 9.6 6.5 2.3 9.5 6.6 16 Kudakurathu 5.58424 73.04485 North Maalhosmadulu 4.8 9.2 6.0 1.3 9.0 4.6 17 Fenfushi 5.38303 72.90252 North Maalhosmadulu 4.5 9.4 5.7 1.1 7.9 4.8 18 Maafilaafushi 5.36102 73.41765 Faadhippolhu 4.6 9.0 4.7 3.2 6.5 3.4 19 Ookolhufinolhu 5.28300 73.62478 Faadhippolhu 5.1 9.4 4.0 2.6 9.5 4.1 20 Fulhadhoo 4.88529 72.92742 South Maalhosmadulu 4.6 8.7 3.6 1.5 9.1 4.6 21 Gaafaru 4.73823 73.49903 Male'atholhu 5.2 8.4 2.4 2.2 6.3 9.7 Preferred regions are highlighted, with colors corresponding to the regions shown in Figure 3-7. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 27 Table 3-3 Preliminary long-list of proposed sites and scoring matrix – concluded Area Suitable Site Site Wind Area of Optimal Planning Environmental for Future Wind Latitude Longitude Resource Validation Value Issues sensitivity Development Final Site Island Name Atoll Name Score ID (/10) Mean Wind Distance to and Proximity Proximity to Wind WGS84 WGS84 Speed Size of Load / to Resorts Environmentally Uncertainty Map datum datum Score Population Score Sensitive Areas Score (/10) (/10) Score (/10) (/10) Score (/10) Relative Weight  100% 10% 10% 40% 20% 20% 22 Akirifushi 4.63754 73.40040 Male'atholhu 5.5 8.3 2.1 4.8 4.1 8.6 23 Thun'bafushi 4.58894 73.58830 Male'atholhu 5.7 8.2 1.8 5.4 5.4 7.2 24 Kodhdhipparufinolhu 4.25915 73.37954 Male'atholhu 5.2 7.4 1.5 8.1 3.1 2.4 25 Thilafushi 4.18277 73.43135 Male'atholhu 4.9 7.1 1.4 7.6 2.5 2.8 26 Vilingilli 4.17088 73.48658 Male'atholhu 3.9 6.9 1.4 4.9 2.8 2.8 27 Kalhuhuraa 4.01015 73.37231 South Male'atholhu 5.7 6.7 1.4 7.4 4.4 5.1 28 Bodukaashihuraa 3.87704 72.95431 South Ariatholhu 4.4 6.4 1.5 1.0 6.9 9.3 29 Kan'dumoonufushi 3.31604 72.89794 North Nilandheatholhu 4.3 4.4 1.1 2.2 8.2 6.3 30 Raiymandhoo 3.09281 73.63802 Mulakatholhu 4.2 3.9 0.0 1.0 9.4 7.7 31 Hulhudheli 2.85976 72.84808 South Nilandheatholhu 4.0 3.2 1.1 2.1 8.3 5.3 32 Maagulhi 2.53890 73.17987 Kolhumadulu 5.0 2.6 0.9 1.6 9.9 9.9 33 Kalhufahalafushi 2.43212 73.35421 Kolhumadulu 4.6 2.4 0.8 1.4 8.3 10.0 34 Isdhoo 2.13230 73.58447 Hadhdhunmathi 4.8 1.2 1.0 2.2 10.0 8.5 35 Bodu Mungnafushi 1.98894 73.30865 Hadhdhunmathi 4.7 1.3 1.8 2.4 9.1 8.2 36 Melaimaa 0.85777 73.17945 North Huvadhuatholhu 5.2 0.6 4.0 2.7 10.0 8.3 37 Fulan'gi 0.68408 73.20195 North Huvadhuatholhu 4.7 0.6 4.2 3.6 7.5 6.4 38 Maaehivakaa 0.27952 73.06335 South Huvadhuatholhu 4.3 1.0 4.7 2.9 10.0 3.0 39 Fuvahmulaku -0.27835 73.41763 Fuvahmulah 5.0 1.1 5.0 5.6 10.0 0.5 40 Hithadhoo -0.57900 73.08881 Adduatholhu 4.8 1.5 5.3 8.4 3.0 0.6 41 Meedhoo -0.58133 73.23536 Adduatholhu 5.8 1.8 5.1 8.7 6.5 1.5 42 Mulikede -0.65846 73.21704 Adduatholhu 5.2 2.0 5.3 10.0 1.6 0.7 Preferred regions are highlighted, with colors corresponding to the regions shown in Figure 3-7. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 28 Figure 3-6 Preliminary long-list of proposed sites for wind measurement masts DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 29 Figure 3-7 Preferred regions for wind measurement masts DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 30 4 MEASUREMENT MAST SPECIFICATIONS AND RECOMMENDATIONS Robust assessment of the wind resource and meteorological conditions are important steps in the development of a validated mesoscale wind map. A well-specified, well-managed wind measurement campaign can be crucial to minimizing uncertainties. The following recommendations are based on DNV GL’s extensive experience of wind resource assessments and meteorological conditions analyses. In some cases, IEC requirements for wind turbine power performance measurements, as detailed in [5], are referenced. Although the requirements for wind resource assessments and wind turbine power performance measurements differ in many respects, certain aspects of the requirements presented in [5] are considered to be valid for wind resource assessments. The following sections detail recommendations for equipment and mounting arrangements on the proposed meteorological masts, and the associated documentation to ensure full traceability of the measurements. 4.1 Mast Mast type A mast specifically designed for the purpose of wind measurement will be used. The mast will comply with relevant standards regarding expected meteorological conditions at the proposed site. The mast type will be a guyed galvanized steel lattice tower with a height of approximately 77 m. The mast will have dimensions that ensure sufficient structural strength, and will include an integrated ladder within the structure bracing. The mast will also include a fall-arrest cable to provide additional security for personnel climbing the mast. The bottom of the mast will be equipped with anti-climb panels. Depending on the region and level of security required, additional security devices, personnel or fencing may be necessary. This will be discussed with Client. The mast will be painted as per ICAO regulation, Annex 14, for day-marking purposes. Additional Aviation warning lights will be installed, as detailed in Section 4.3. 4.2 Equipment Wind speed All anemometers installed will be classified as Class 1 according to the requirements of IEC [5] and will be individually calibrated by a MEASNET-approved institution. Parallel anemometers are recommended at the upper measurement height but also at each lower measurement height as indicated in Section 4.4.1.1. The inclusion of a redundant anemometer at lower heights shall be discussed with the Client. It is DNV GL’s opinion that the installation of a single sensor type on a given met mast introduces an additional level of risk associated with sensor specific flaws or biases that may be inherent in the sensor design. An effective way to reduce this risk is to introduce sensors from multiple manufacturers on the same mast. This approach to sensor installation is designed to yield a more stable measurement campaign that also minimizes the costs associated with possible future maintenance procedures. Furthermore, this practice provides greater clarity in identifying spurious measurements when recorded wind data are subsequently analyzed. Implementing this DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 31 recommendation will materially reduce sensor specific flaws and protect against measurement biases that can introduce unnecessary error. Several anemometers will be required on each meteorological mast, in order to provide redundancy and investigate the vertical variation of wind speed. Recommendations for the number of anemometers, mounting arrangements and installation heights are detailed in Section 4.4. The power supply for the anemometers is provided by the internal battery power supply within the data logger, detailed in Section 4.3. Wind direction Wind vanes will be used to measure wind direction. To provide redundancy, two wind vanes will be installed on each meteorological mast. Recommendations for installation heights are detailed in Section 4.4.1.3. Atmospheric conditions Calibrated temperature sensors with radiation shields, calibrated air pressure sensors and humidity sensors will be deployed on each mast. Sensors to measure atmospheric conditions are useful to support quality assurance checks of the primary wind and direction measurements, and also provide valuable data to assess turbine suitability for future wind farm development. The air pressure sensor will be mounted in a weatherproof box which will be adequately ventilated; this ensures that pressure readings are not influenced by air pressure distribution around the box. Data logger and Communications Campbell Scientific data loggers will be installed on every mast. These loggers record and store data with a continuous sample rate of 1 Hz, and an averaging interval of 10 minutes will be used. As a minimum, the following statistics will be recorded: • Time stamp; • Mean, standard deviation and maximum wind speed; • Mean and standard deviation wind direction; • Mean and standard deviation temperature, air pressure and relative humidity; and • Power supply voltage. The data logger will be located in a lockable weather-proof housing. Precautions will be undertaken to ensure moisture cannot enter instruments, cabling or the logger housing. Data loggers can be installed at various heights depending on the location. For example, installing the logger at 3 m or above ensures that access can be gained with a tall ladder only. Measures shall be taken to ensure the security of the data logger and will be discussed with the Client. The data logger will have storage capability for at least 6 months of recorded data, from the addition of a external compact flash data storage. Flash memory cards are used to store data and these should be easy for local staff to retrieve and replace, if necessary. Prior to the site visit, and as indicated in the Client’s request for proposals, a land-based GSM modem and suitable antenna are planned for data transmission. For remote locations without mobile telephone coverage, satellite communication may be utilized if necessary. This will be confirmed after the site visit and discussions with the Client. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 32 The data logger clock will be set to local standard time in the Maldives. The logger clock will be regularly checked and corrected to ensure the correct time. 4.3 Other equipment 4.3.1 Power supply The wind measurement masts will be autonomous. Power for the logger, communications and sensors will be supplied by battery power supply within the data logger and from an external battery, housed in the weatherproof enclosure. The batteries will be charged by an externally-mounted solar panel, installed on the mast. The system will be configured so that batteries will remain suitably charged, even during winter months, with realistic periods of low light levels. The solar panel will be installed to maximize exposure to the sun. A separate power supply will be installed for the Aviation warning lights, as discussed below. 4.3.2 Aviation warning lights Where required, ICAO Annex 14 compliant Aviation warning lights will be installed at the top and mid- point of masts. Care will be taken to ensure that flow distortion on the wind speed measurements, caused by the aviation warning lights, is minimized. Top Aviation warning lights will be installed 1.5 m below the anemometers at the top of the mast, which are installed on the goal post arrangement. Mid- point lights will be mounted further down the mast and at least 1.5 m vertically from the closest anemometer. The aviation warning lights will be supplied with integrated solar panels and batteries, suitable to provide adequate lighting intensity during low light periods. 4.3.3 Lightning protection Although it is not possible to provide absolute protection from a direct strike, precautions will be taken to protect against lightning damage to the mast and equipment. The sensors will be connected with screened cables that, together with the data logger and mast, will be connected to a local earth. A lightning rod will be installed at the top of the mast and a protection umbrella of 60° to sensors mounted at the top of the mast will be provided. The lightning rod will be a copper rod. The rod will be fastened to a tower leg at the top, and with a copper wire mechanical attached to the tower. Another copper rod will be driven into the ground near the mast base, and the tower will be clamped to this rod via a copper tail. Due to the attractiveness of exposed bare copper cable to vandalism, DNV GL suggests not installing a bare copper cable down-run on the tower. This will be further discussed with the Client. As the anemometers installed at the top of the mast are the primary instruments on the mast, care will be taken to ensure the flow distortion caused by the lightning rod on the wind speed measurements is minimized. 4.3.4 Bird deterrents Depending on local regulations, mast locations and requirements from the Environmental Protection Agency (EPA) of the Maldives, the installation of bird deterrents on the mast guy wires may be a requirement. Bird deterrents are also commonly referred to as bird deflectors. If necessary, bird deterrents will be mounted according to the requirements of local standards and environmental best practices. However, care will be taken to ensure that flow distortion on the wind speed measurements, caused by the bird deterrents, is minimized. If regulations allow, bird deterrents DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 33 will be at least 1.5 m vertically above or 3 m vertically below the closest anemometer. Depending on; the size of the bird deterrents; the magnitude of possible wind flow inclination and the horizontal distance of the bird deterrents from the closest anemometer, these vertical distances may need to be increased. 4.4 Measurement configuration The IEC provides the industry standard for cup anemometer and wind vane mounting arrangements [5], however it is noted that this presents requirements for wind turbine power performance measurements. As a result, the requirements presented in [5] focus on measurements at hub height and in discrete direction sectors. For the assessment of wind resource and meteorological conditions, it is important that measurements are undertaken at a range of heights and that distortion of the wind flow is minimized in all direction sectors, particularly the prevailing wind direction sectors. 4.4.1 Recommended measurement configuration 4.4.1.1 Anemometer mounting arrangements Anemometers installed at the top of a meteorological mast are primarily used as initiation instruments for wind flow modeling. Anemometers installed at lower heights are used to investigate vertical variation of wind speed at the mast location and as reference instruments should the primary anemometers at the mast top fail. Anemometers at the top of the mast will be installed on a goal post arrangement. The horizontal separation will be a minimum of 2 m, and the height above the top of the mast will be a minimum of 3 m, for a total measurement height of 80 m. All anemometers below the goal post will be mounted on slender horizontal booms and vertical arms of circular section. The horizontal booms will be securely attached to the mast and will not flex in the wind. The angle deviation of the anemometer will be less than 2° from vertical. The maximum center-line flow distortion due to the mast will be kept below 0.5%, as per [5]. In order to achieve this, the length of horizontal the booms will be approximately 2 m to 3 m. this will depend on the final design and porosity of the masts; details of this calculation are given in [5]. For example, for a square section lattice mast with a thrust coefficient, CT of 0.5, the horizontal booms will ensure that the cups of the anemometer are at least 5.7 mast face widths from the mast. In order to avoid significant flow disturbance at an anemometer due to its own horizontal boom, the vertical arm will ensure that that cups of the anemometer are at least 15 boom diameters above the horizontal boom. In order to further minimize flow disturbance at the anemometers due to the mast, the horizontal booms will be orientated, as much as possible, 90° to the prevailing wind direction. Due to the topography and anchoring challenges, there may some deviations with this best practice. This will be confirmed during the site visits. All anemometers installed in parallel will be installed on horizontal booms orientated at 180° to one another. An absolute separation distance of 1.5 m between the anemometers and the guy wires will be maintained on all masts. It is recommended that two anemometers are installed in parallel at each measurement height on all masts used for the assessment of wind resource and meteorological conditions. Installing two anemometers in parallel at exactly the same measurement height improves the accuracy of the wind speed measurement at that height and provides redundancy in the event that one of the two DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 34 anemometers should fail. Flow distortion due to the mast can be further minimized by selecting wind speed data from the two anemometers on a directional basis. Furthermore, issues such as anemometer degradation can be identified with greater accuracy. 4.4.1.2 Wind vane mounting arrangements Although wind direction measurements are less sensitive to flow distortion caused by other objects, the general principles for mounting arrangements of anemometers in Section 4.4.1.1 will also be applied to the mounting arrangements of the wind vanes. In particular, wind vanes will not be installed at the same height as anemometers. The wind vanes will be installed on horizontal booms, with the north of the wind vane (i.e. dead band) aligned along the boom axis, pointing toward (preferably) or away from the mast. This will enable the wind direction offset to be assessed easily from the ground with the aid of a compass once the mast has been installed. The wind direction offset will either be programmed into the data logger or applied during analysis of the data. The alignment of the north of the wind vane shall be documented in the mast installation report, described in Section 4.5. 4.4.1.3 Overall sensor mounting arrangement and heights Recommended installation heights and mounting arrangements for instrumentation on the masts are shown in the Table 4-1 below. Table 4-1 Instrumentation Summary for 80m met masts Height [m] Instrument Type Mounting arrangement 80 MEASNET Calibrated Anemometer Goal post 80 MEASNET Calibrated Anemometer Goal post 77 Wind vane Horizontal boom 77 Calibrated temperature sensor On tower leg 60 MEASNET Calibrated Anemometer Horizontal boom 601 MEASNET Calibrated Anemometer Horizontal boom 58 Wind vane Horizontal boom 40 MEASNET Calibrated Anemometer Horizontal boom 401 MEASNET Calibrated Anemometer Horizontal boom 20 MEASNET Calibrated Anemometer Horizontal boom 201 MEASNET Calibrated Anemometer Horizontal boom 3 Calibrated temperature sensor On tower leg 3 Relative Humidity sensor On tower leg 3 Calibrated Barometer sensor In Logger Enclosure, on tower leg Logger and communications 3 In enclosure, on tower leg equipment 1 Redundant anemometers to be discussed with Client during in-country workshop DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 35 The sensor installation heights presented in the table above may be altered for practical reasons or so that sensors are not affected by any objects that may cause flow distortion. It is typically not recommended to install anemometers below 25 m to estimate wind resource at large scale wind turbine hub heights, however, wind resource evaluation at a height of 20 m, for small-scale wind development, is one of the current project goals. In areas of significant forestry, it may be necessary to reassess the installation heights of the lowest anemometer to avoid surface effects. For anemometers installed in parallel, the cups of the anemometers shall be at exactly the same measurement height. With the exception of anemometers installed in parallel, a minimum vertical separation distance of 1.5 m will be maintained between all sensors. Exact sensor installation heights to an accuracy of 0.1 m, and the allocation of individual sensor serial numbers to data logger channels and installation heights, will be documented in the mast installation report, described in Section 4.5. For ease of access, pressure and relative humidity sensors will be installed at 3 m AGL. Thermometers at the top and ground levels will be installed to allow a more refined analysis of variability in thermal effects. Refer to Figure 4-1 for recommended mast instrumentation schematic configuration. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 36 Figure 4-1 Recommended mast instrumentation DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 37 4.5 Documentation For quality and traceability purposes, a detailed mast installation report will be prepared for each individual wind measurement mast. In addition, if there are any changes to the mast and equipment during the measurement period occurs, it will be documented in a mast maintenance log. 4.5.1 Mast installation report The installation report will be prepared for each individual wind measurement mast, which will contain, at a minimum of the following: General information: • Site and mast name; • Mast installation company; • Installation date; • Grid coordinates of mast (including details of coordinate system and datum); • Elevation of mast above sea level; and • Description of surroundings, including distance from mast and height of any significant obstacles or terrain features. Mast and equipment: • Mast type and height; • Lattice mast dimensions; • Exact installation heights above ground level for all sensors; • Dimensions of all horizontal booms and vertical arms installed on the mast, including boom diameters and lengths for all horizontal and vertical members; • Orientations of all horizontal booms, with reference to geographic north; • Orientation of wind vane north for all wind vanes; • Sensor types, serial numbers and corresponding installation heights; • Calibration certificates for all anemometers; and • Data logger type and serial numbers. Data logger configuration: • Data logger program; • Wind vane offsets to geographic north and whether these have been programmed into the data logger; • Details of power supply; • Details of data retrieval; and • Details of data logger clock setting. Commissioning: • Data showing first hour of operation after installation and confirmation that it complies with general site observations at the time. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 38 Photographs: • Photographs of mast, all booms and all sensors as mounted on the mast; • Panoramic photograph from mast location; and • Photographs of any significant obstacles in the vicinity of the mast. 4.5.2 Maintenance log A maintenance log is a highly useful aid during data analysis. A maintenance log detailing all work carried out on the mast during the measurement campaign will be kept. For each intervention at the mast, the following will be noted: • Date and time of commencement and completion of the intervention at the mast, as recorded by the data logger on the mast (if functional at the commencement of the work); • Reason for the intervention; • Details of work carried out, including a clear description of any changes to equipment or mounting arrangements; and • Serial numbers of any replaced and replacement sensors, including calibration certificates for replacement anemometers. The following will also be documented in the mast history: • Details of changes to the mast surroundings during the measurement campaign (felling of trees, construction of buildings or wind turbines, etc.); and • Details of any periods of missing data (affected sensor, start, end, problem if known). DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 39 5 REFERENCES [1] “Mesoscale Wind Modeling Report 1- Interim wind atlas for Maldives”, DNV GL,702909-AUME-R- 01-A, February 2015. [2] “TERMS OF REFERENCE – Renewable Energy Resource Mapping: Wind, The Maldives, South Asia Region”, Project ID: P146018, ESMAP. [3] “Maldives Submarine Cable Interconnection: Pre-feasibility study”, USAID South Asia Regional Initiative for Energy, Contract Number 386-C-00-07-00033-00 Task Order 1.9, 15 April 2010. [4] “Environmentally Sensitive Areas”, Environmental Protection Agency, Republic of Maldives, 2011 [5] “Wind turbines – Part 12: Power performance measurements of electricity producing wind turbines”, IEC 61400-12:2005 (E). DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 40 APPENDIX A – DETAILED SITE SELECTION IMAGES DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 41 Figure A-1 Populated islands within the north of the Maldives and their average electrical consumption DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 42 Figure A-2 Populated islands within the center of the Maldives and their average electrical consumption DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 43 Figure A-3 Populated islands within the south of the Maldives and their average electrical consumption DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 44 Figure A-4 Listed resorts and airports within the north of the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 45 Figure A-5 Listed resorts and airports within the center of the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 46 Figure A-6 Listed resorts and airports within the south of the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 47 Figure A-7 Listed Environmentally Sensitive Areas within the north of the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 48 Figure A-8 Listed Environmentally Sensitive Areas within the center of the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 49 Figure A-9 Listed Environmentally Sensitive Areas within the south of the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 50 Figure A-10 Site scoring map for locating mesoscale wind validation masts in the north of the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 51 Figure A-11 Site scoring map for locating mesoscale wind validation masts in the center of the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 52 Figure A-12 Site scoring map for locating mesoscale wind validation masts in the south of the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 53 Figure A-13 Preliminary long-list of proposed sites for wind measurement masts in the north of the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 54 Figure A-14 Preliminary long-list of proposed sites for wind measurement masts in the center of the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 55 Figure A-15 Preliminary long-list of proposed sites for wind measurement masts in the south of the Maldives DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 56 ABOUT DNV GL Driven by our purpose of safeguarding life, property and the environment, DNV GL enables organizations to advance the safety and sustainability of their business. We provide classification and technical assurance along with software and independent expert advisory services to the maritime, oil and gas, and energy industries. We also provide certification services to customers across a wide range of industries. Operating in more than 100 countries, our 16,000 professionals are dedicated to helping our customers make the world safer, smarter and greener. DNV GL – Report No. 702909-AUME-R02, Rev. C, Status: FINAL – www.dnvgl.com Page 57