METHODOLOGY

The State of Karnataka in western central India is approximately within latitudes 11^o31' and 18^o45' North and longitudes 74^o12' and 78^o40' East;see. Figure 1with the different agroclimatic zones. Karnataka is situated on a tableland where the Western and Eastern Ghat ranges converge into the Nilgirihillcomplex.Karnataka's total land area is 191,791 sq.km. It accounts for 5.35%of the total area of the country and ranks eighth in size among major States. For administrative purpose the State is divided into 27 districts, which are sub divided into 175 taluks. Karnataka is divided into 10agroclimatic zones, considering texture, depth and physiochemical properties of soil, rainfall, elevation, topography, major crops and type of vegetation. The zones are (1) Northeastern Transition, (2) Northeastern Dry, (3) Northern Dry, (4) Central Dry, (5) Eastern Dry, (6) Southern Dry, (7) Southern Transition, (8) Northern Transition, (9) Hilly zone, and (10) Coastal.

It is customary to average the wind speeds during each hour and use the hourly mean wind speed as the basic parameter in calculations of wind power. The relationships between annual mean wind speed (at anemometer height of 10 m) and potential value of the wind energy resource as considered in India are listed in following table.

In locations where data are not available, a qualitative indication of a high annual mean wind speed can be inferred from geographical location, topographical features, wind-induced soil erosion, and deformation of vegetation. However, accurate determination of the mean annual wind speed requires anemometer data for at least 12 months. Availability of wind energy and its characteristics have been studied for 45 locations in Karnataka based on primary data at selected locations and data collected from the meteorological observatories of the India Meteorological Department (IMD), where 3-cup anemometers with 127mm diameter conical cups, in conformity with international practice, are used. Anemometers at different meteorological stations are normally at 10m height, but if at a different height the data are adjusted to 10m by the IMDaccording to methods of .the World Meteorological Organization. Since modern wind turbines have hub heights greater than 10m, we extrapolate to 30m above ground using equation 1.

V = V_o [h/h_o]^k -------(1)

Where, v: wind speed at height h (m/s), V_o:wind speed at anemometer height h_o (m/s),

h = height at which wind speed is measured m), h_o: anemometer height (10 m), k = height exponent (0.14)

Wind energy conversion systems would be most effective in these locations during May to August. The Energy Pattern Factor (EPF) and Power densities at 30m are computed for sites with hourly wind data. With the knowledge of EPF and mean wind speed, mean power density is computed for the locations with only hourly monthly data. Wind power density of a stream of air with density d moving with a velocity V_m is given by,

P = K_Em d V_m³ / 2 ----------(2)

Where, K_Em is the energy Pattern factor.

K_Em = (V_i³ / N_m) / V_m³ --------(3)

Where, V_i : Hourly wind speed during the month, Nrn:number of hourly wind speed values during the month, and V_m : monthly mean wind speed. For a Rayleigh distribution of wind speed, K_Em= 1.91. Values of K_Em varies from 1.05 (Jogimatti), 1.33 (Chikkodi) to 1.44 (Gokak, Khamkartti).