1. WIND RESOURCE ASSESSMENT TECHNIQUES
Dr.S.Gomathinayagam
Executive Director
Centre for Wind Energy Technology
Chennai
K.Boopathi
Scientist & Wind Resource Assessment
Unit Chief,WRA
Wind Resource Assessment
Centre for Wind Energy Technology
Chennai

2. WIND Air in motion i.e. motion of air relative to the earth’s surface.
Free, clean and inexhaustible energy
It is intermittent source
One day it calm, howling next
It will vary place to place and time to time

3. WIND RESOURCE-GLOBAL WIND SYSTEM
All renewable energy (except tidal and geothermal power), and even the energy in fossil fuels, ultimately comes from the sun. About 1–2% of the energy coming from the sun is converted into wind energy
The region around equator at 0 deg latitude are heated more by the sun than the rest of the globe. Due to this flow of air takes place from the cold regions to hot regions.

4. Wind speed characteristics
Horizontal and Inter annual Variability
Temporal and Inter annual Variability
Vertical Wind Variability

5. Atmospheric boundary layer and Vertical wind profile
Vertical wind profile for different roughness lengths z0, assumed “geostrophic wind” of
15 m/s

6. Wind Regime in India
Wind climatology in India is influenced by the strong monsoon circulations
South west monsoon during May to Sept brings the best winds
Wind speed during November to March is low, except in Southern tip of Tamil Nadu
Best Windy Sites are in Kerala, Karnataka, Tamil Nadu, Gujarat, Andhra Pradesh and Maharashtra

7. POWER IN THE WIND From Wind to Electric Power
Power (translation) = Force x Velocity (P=F V) or
Power (rotation) = Torque x rotational speed (P=T x co)
P= KE*m
KE - Kinetic Energy ,=1/2mV 2 m - mass flow rate=pAV
Pwind = Cp 1/2 pV3 A
Cp efficiency (“Betz” max. = 16/27)
1/2 pV2 Dynamic pressure at 1 m2
p Air density (~1.22 kg/m3)
V Wind speed
A Gross rotor area

8. Wind Resource Assessment
Main objective is to identify potentially windy areas that also possess other desirable qualities for wind project development

9. WIND RESOURCE ASSESSMENT
TECHNIQUES
Prospecting (Large area Screening & Field visits).
Validation (Wind measurements & Data Analysis)
Micro Survey & Micrositing.

10. PROSPECTING

11. PROSPECTING STEPS Preliminary area identification
Ranking of candidate sites
Selection of tower location(s)
Development of a monitoring plan
Quality assurance

12. Preliminary Area Identification
Objective is to determine or verify whether sufficient wind resources exist within an area to justify further site-specific investigation
Large area screening- wind resource map look up
use of existing wind data-nearby airport
topographic indicators
field surveys
flagged trees
accessibility
land use– obstructions
available land area

13. Large area Screening and Existing data
large-area screening usually begins with a review of
existing wind resource maps, data and
other meteorological informations (pressure, temperature etc.)
analysis of the climatology of the region along with the topographical maps (such as terrain form, land use and land cover, and other logistics like accessibility, grid availability etc.).
use of existing wind data-nearby airport
nearby airport measurement wind data
Long term re analysis data (NCEP/NCAR/MERRA)

14. Installable Potential
WPAD MAP AT 50 m
States / UTs
Installable Potential
(MW) 50 m Level
Andaman & Nicobar 2
Andhra Pradesh
5394
Arunachal Pradesh*
201
Assam* 53
Chhattisgarh* 23
Gujarat
10609
Himachal Pradesh * 20
Jammu & Kashmir *
5311
Karnataka
8591
Kerala
790
Lakshadweep 16
Madhya Pradesh
920
Maharashtra
5439
Manipur* 7
Meghalaya * 44
Nagaland * 3
Orissa
910
Rajasthan
5005
Sikkim * 98
Tamil Nadu
5374
Uttarakhand *
161
Uttar Pradesh *
137
West Bengal* 22
Total
49130

15. State Name
Installable Potential MW
Andaman &Nicobar Islands
365
   Andhra Pradesh
14497
   Arunachal Pradesh*
236
   Assam*
112
   Bihar
144
   Chhattisgarh*
314
   Dieu Damn 4
   Gujarat
35071
   Haryana 93
   Himachal Pradesh * 64
   Jharkhand 91
   Jammu & Kashmir *
5685
   Karnataka
13593
   Kerala
837
   Lakshadweep  16
   Madhya Pradesh
2931
   Maharashtra
5961
   Manipur* 56
   Meghalaya * 82
   Nagaland *
   Orissa
1384
   Pondicherry
120
   Rajasthan
5050
   Sikkim * 98
   Tamil Nadu
14152
   Uttarakhand *
534
   Uttar Pradesh *
1260
   West Bengal* 22
   Total
102788

16. TOPOGRAPHIC INDICATORS

17. Field visits
To look for physical evidence to support the wind resource estimate developed in the large-area screening.
Another purpose of the site visit is to select a possible location for a wind monitoring station. Consistently bent trees and vegetation, for example, are a sure sign of strong winds.

18. Ranking of Candidate Sites
Objective is to compare areas to distinguish relative development potential
In addition to accessibility, land use, obstructions, and available land area, siting criteria could include:
proximity to transmission lines
potential impact on local aesthetics
cellular phone service reliability for data transfers
potential avian interactions

19. Standard Wind Class US Wind Class
A site can be classified as one of the Standard seven classes depending on Wind Power Density/Wind Speed
available at 50 m above ground.
Class
Speed(m/s)
WPD(W/Sq.m) 1
0-5.6
0-200 2 3 4 5 6 7

20. Site Selection A number of effects have to be considered :
The power output of a wind rotor Increases with the cube of the wind speed. This means that the site for a windmill must be chosen very carefully to ensure that the location with the highest wind speed in the area is selected. The site selection is rather easy in flat terrain but much more complicated in hilly or mountainous terrains.
A number of effects have to be considered :
1. winds hear; the wind slows down, near the ground, to an extent determined by the surface roughness.
2. turbulence; behind building, trees, ridges etc
acceleration; (or retardation) on the top of hills, ridges etc.
Inflow wind
Extreme wind
Gusts
Wake effects

21. Turbulence and Acceleration of ridge and Obstacle
The flow inclination must not exceed ± 8 degree for any wind direction
Turbulence is variations in wind speed
Back ground turbulence
Wake turbulence
Close to an obstacle such as a building the wind is strongly influenced by the presence of the obstacle. The effect extends vertically to approximately three times the height of the obstacle, and downstream to 30 to 40 times the height. If the point of interest is inside this zone, it is necessary to take the sheltering effects into account, whereas if the point is outside the zone the building should be treated as a roughness element.
The buildings and rows of trees shelter the met. mast in the centre of the drawing.
tops of ridges experience higher wind speeds due to the effect of wlndshear
The ideal slope angle is said to be 16° (29 m rise per 100 m horizontal distance) but angles between 6° and 16° are good

22. VALIDATION

23. Met Mast

24. Instruments for Measuring wind speed and Direction
cup anemometer
vane anemometer
ultrasonic anemometer
hot-wire anemometer
other “high-tech” device (SODAR,LIDAR)

25. Instruments small vertical axis wind wheel
Direction of wind is an important factor in the siting of a wind energy conversion system. If we receive the major share of energy available in the wind from a certain direction, it is important to avoid any obstructions to the wind flow from this side. Wind vanes were used to identify the wind direction in earlier day’s anemometers
small vertical axis wind wheel
rotational speed proportional to wind speed
two ways taco generator (analogue signal)
frequency signal (optoelectronic)
most commonly used,
sufficient for most tasks in wind technology
wide range of qualities
logging of time series (10-minute or 1-hour averages)
channels for 3 or more wind speeds and wind vanes,
air pressure, 2 or more temperatures, humidity
power supply by solar panel and battery
safety system for data storage in case of break down of power supply
data storage capacity minimum of 2 months

26. REMOTE SENSING INSTRUMENTS
SODAR

27. Analysis Monthly variation Diurnal variation
number of manipulations with these data, basically looking at two aspects:
time distribution
frequency distribution
Plotting the monthly averages of each hour of the day shows the diurnal fluctuations of the wind speed in that particular month
Monthly variation
Diurnal variation

28. TECHNIQUES FOR ESTIMATING WIND RESOURCES
These techniques can be used screen candidate resource areas for sites with high potential or to estimate wind energy characteristics at a specific location.
numerical modeling of flow over terrain
physical modeling of flow over terrain
topographical indicators of wind energy potential
biological indicators of wind energy potential
geomorphol ogi cal indicators of wind energy potential
social and cultural indicators of wind energy potential.
Numerical Modeling
Synoptic scale -is a horizontal length scale of the order of 1000 kilometres (about 620 miles) or more
Meso-about 5 kilometers to several hundred kilometers
Micro-1 km or less, smaller than mesoscale

29. WIND RESOURCE ASSESSMENT UNIT
Offshore Wind Mapping
Study based on coastal wind monitoring stations.
Study based on data from data buoy deployed by NIOT.
Study based on SAR in association with RISO –DTU
Study based on QUICK SCATT in association with INCOIS
SDI, Scotland has been encaged for preparing feasibility study.
Measurements are being initiated at Dhanushkodi in Ramanathapuram, Tamil Nadu

30. SAR winds
ENVISAT ASAR WSM images from the European Space Agency (ESA). The WSM – Wide Swath Mode – scenes each cover 400 km x 400 km. As examples two of the wind maps are shown in Figure. The figure 1(top) shows an example from 4 December characterized by strong winds whereas the Figure 2 (bottom )shows much weaker winds on 25 September 2010.
A total of 164 WSM scenes are used. Most of the 164 scenes are from ESA’s ordering system EOLISA and sent on DVD to Risø DTU but a few are taken from ESA’s rolling archive.
There are a total of 164 ocean wind maps out of which 72 are observed in the morning and 92 in the evening
Ocean wind map from ENVISAT ASAR WSM from 4 December 2010 at UTC in South India.
Ocean wind map from ENVISAT ASAR WSM from 25 September 2010 at UTC in South India.

31. OFFSHORE WINDFARM (PROPOSED) AT DHANUSKODI RAMESHWARAM AND KANYAKUMARI

32. MICROSURVEY & MICROSITING

33. MICRO SURVEY

34. What is micro siting ?
Micro siting is a way to optimize the park layout in any given site to give the optimum production on site.
- Wind measurements
- Roughness, Obstacles, Orography
- Wind resource estimate
- Turbine layout
- Production estimate, incl. wake losses to other turbines
- Load calculation to ensure a 20 year design lifetime
- Calculate sound emission from the turbines to the
nearest neighbor.
- Create a visualization of the park.
- Calculate shadow flickering
Recommend another turbine type, turbine layout, hub height, wind sector management or measurement campaign
All this is something that is done before the park is erected so you can calculate the feasibility of the project.

35. Analyze and reduce risks
Benefits of siting
Optimize production
Analyze and reduce risks
The most important aspect in the siting is to optimize the production capacity so the customer gets the most out of the project. But not less important to minimize the risks for Vestas that comes with choosing the wrong turbine for the project. Minimizing loads and making the project as feasible for Vestas as possible. Bad siting causes at times turbines to break down and not being able to withstand the 20 years lifetime as it should. This is very expensive for Vestas both in hard cash but not least in the bad reputation it brings along.

36. Conclusions The wind resource drives project viability.
Wind conditions are site-specific and time/height variable.
Accuracy is crucial. Wind resource assessment programs must be designed to maximize accuracy.
Combination of measurement and modeling techniques gives the most reliable result.
Know the uncertainties and incorporate into decision making.
Good financing terms depend on it.

37. Thank you