Wind energy potential in Iraq

Journal of Wind Engineering and Industrial Aerodynamics, 27 (1988) 179-189

179

Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands

WIND ENERGY POTENTIAL IN IRAQ

A S K DARWISH and A A M SAYIGH Department of Engineering, University of Reading, Whiteknights, RG6 2AY, United Kingdom

Reading,

ABSTRACT Ten years' wind data for nine locations inside Iraq and six outside it in the neighbouring countries were used to calculate the potential of wind energy in Iraq. The nine selected stations were used to draw the regional distribution of mean wind speed in Iraq. It was found that four distinctive regions exist 2.0 - 3.0, 3.1 - 4.0, 4.1 - 5.0, and greater than 5.1 m/s regions. A full statistical analysis has been carried out for each station which involved monthly average speed, annual values of shape and scale parameters of Weibull distribution, the average speed frequency, Weibull distribution, speed distribution and their cumulative duration in hours, and the diurnal pattern of wind spped of each location. It can be seen that one sixth of the country enjoys annual wind speed greater than 5.0 m/s. Wind farms could be used in Iraq to supply electricity to many parts.

INTRODUCTION The population of Iraq is about 14 million and its area is 450,000 km 2. Sixty per cent of the country is desert. and 37.5 North and longitude 39 - 48 East. country is 5016 MW, ~I).

Iraq lies between latitudes 29 The electricity power of the

At present about 10% of this power is met by hyrdro

power and the rest is generated from oil.

Oil was discovered in 1927 and its

present production is about 3 million barrels per day.

The country has about

3,000 hours of sunshine per year and an average solar radiation intensity of 240 W/m ~ (i). Wind energy in Iraq has never been studied thoroughly.

A few attempts

have been made to analyse the wind potential in Iraq (2, 3), but none of them were extensive.

This paper describes the different wind zones in Iraq and

calculates the potential wind energy available in different parts of the country. The nine different stations were Mosul, Anah, Baghdad, Habbania, Rutba, Hal, Najaf, Nasiriyah and Basra; see Figure I. wind speed averages from reference

(4).

Ten years' daily and monthly

(1960 - 1970) are shown in Figure 2.

All the readings are taken at a height of I0 metres

above the ground level.

The readings frequency is in an hourly period.

the readings are automatically recorded.

0167-6105/88/$03.50

The data are taken

© 1988 Elsevier Science Publishers B.V.

All

180 Table 1 shows the geographical data for the nine locations.

Using the

yearly mean wind speed, a map of various wind regimes in Iraq has been drawn. Figure 3 shows four regimes, than 5.0 m/s.

2.0 - 3.0, 3.1 - 4.0, 4.1 - 5.0 and greatec

This map was drawn by utilizing plot of monthly average wind

speeds of all locations as well as the border areas surrounding Iraq.

The

previallng wind in most of these stations is NW (North-West). Figure 4 shows a typical plot of Baghdad which indicates that a yearly average of wind speed of 3.91 m/s. The paper describes the different statistical analysis in the form of graphs for the town of Baghdad.

Similar analyses were carried out for the

rest of the locations but not necessarily shown in the text.

A typical

frequency curve for the year 1965 in Baghdad is shown in Figure 5, while the average speed frequency curve is in a histgram form and the duration curve for the period 1960 - 1970 are shown in Figures 6 and 7.

In some cases it is

preferred to plot the time during which the wind speed was smaller than a given wind speed, and when this is plotted versus the wind speed a cumulative distribution results

(Figure 8 (b), see table 2).

All readings were taken at a height of 10 metres above the ground and in an open area, away from any buildings or obstacles. taken into consideration in each station,

The diurnal pattern was

for example Figure 9 shows this

variation during the month of June 1965 in Baghdad.

The best wind speed

averages greater than 4 m/s in specific years for two locations in Iraq are shown in Figures I0 and II.

The maximum wind speeds during the period

(1960 -

1970) for Anah are shown in table 3.

MATHEMATICAL ANALYSIS The effect of different height on wind speed has been studied by some authors,

(5,6) and the common expression which can be used is V1

v-2 =

HI

~

( 1 )

(~1

Where vl is a wind speed at height HI of I0 m above ground level, v2 is a wind speed at height H2 above ground level, and ~ is a power index equal to I/7 of (0.1429). The roughness factor (e) for Anah is determined by substituting the wind speed data obtained with the anemometer height in various wind directions, and found to be 0.240. The power P of the wind at speed V m s to the wind direction

-i

and per unit area perpendicular

, is P

510 V3

(2)

181 This is a combination

of kinetic energy per unit mass, 0.5 P V2, and the

mass flow rate, V, where P is the air density.

Therefore,

at a given location

the overall annual energy in the wind depends on the distribution speeds.

of wind

This means the number of hours during which the speed was, for example,

between 5 and 6 m s -I or 6 and 7 m s -l, and so on. It has been studied in reference situation

to look for mathematical

(5) that, it is quite logical in such a

functions

and duration curves as closely as possible, of a windmill the Weibull

later on.

In this respect much attention has been given to

function reference

imental data as mentioned The Weibull distribution

M (v)

(8) is charactsrised

by two parameters:

dM(V)dv =

the shape

function

(C.D.F.), M(V) ( 3 )

density function cK

cV k-I

(P.D.F.)

f (V),

V K (-(3))

exp

The average wind speed (Vm) can be expressed

( 4 ) in terms of C and K or

vice versa but the integration which deals with it is too complex. r (x) is called gamma function is required, = o f y x-i

r(x) • ".

v

=

m

Equations

and

M(v)

=

(fv)

=

c.

e-y

r(l +

dy

( 5 )

I)

( 6 )

Lysen,

(6):

i - exp (- r K (l + i) (V) K ) k V m k

(V)k

F k(l + i)

v

exp

( 7 )

(-rk (I + I) ( Z ) k)

~

~

m

(I + I/K).

Therefore

i.e.

(3) and (4) can be written by using equation

v

( 8 )

v m

(5) tabulated

the values of K from I to 4 and its correspondent

rk(1 + i/K). G which is an approximation

G/rk (I + I/K).

(7).

and scale parameter c (m s-l).

dlstrlbution

and the probability =

for example see reference

V K I - exp (- ( 3 ) )

=

f(V)

(8), since it is a good match with the exper-

in many references,

parameter K (dimensionless) The cumulative

that approach the frequency as a tool to predict the output

It happens

for gamma-functlon,

and

that when K = 2 Raleigh distribution

with recently developed Weibull distribution.

coincides 1 Therefore K = 2 and r2(l- + ~) =

7/4 which leads into: M(v)

=

I -exp

(- z ( v ) 4v

2

)

( 9 )

m

and

f(v)

v v2

exp

(_~v 4 (~)2

m

m

)

( 10 )

182 To estimate Weibull parameters

three methods exist.

They are

discussed by reference 5: a.

Weibull p r o b a b i l i t y paper

b.

S t a n d a r d - d e v i a t i o n analysis,

c.

Energy pattern factor analysis

Considering lo~arithim 1

n

of (-1

Table

(a), therefore using e q u a t i o n

both

its

(t

M (v)))

n

-

4 is

plotted against

and

sides

leads =

prepared.

K 1 V n

The

(3) and taking natural

to: -

K 1 C n

observed

values

InV as shown in figure 12.

(

of

1 ( - 1 (1 n n

-

M (v)))

11

)

are

Using the least square method, a

straight line is fitted to the above m e n t i o n e d data which is also drawn in the same figure in order to obtain the parameters K & C. the straight line, while It is possible and as an example Figure

K is the slope of

is the intercept on the vertical axis.

to draw Weibull d i s t r i b u t i o n for all stations in Iraq,

figure

13 shows Weibull distribution for Baghdad.

14 shows the yearly values of K and C for the period

for Baghdad. variations

(-KInV)

It is clearly shown in this figure that there exists

from one year to another.

However,

large

Therefore one or few years average

cannot be r e p r e s e n t a t i v e of the real situation. number of years where one

Ten years is the m i n i m u m

can get a reasonable mean value in a given site.

it is possible to carry out a rough estimate of the wind

power on a unit area in a given site w i t h an average wind speed, _3 mean speed Vm) and u s i n g 3 R a y l e i g h d i s t r i b u t i o n of 0.95 V m (9). If P

(1960-1970)

= 1.225 Kg m

power density is 74.48

(yearly

, then at an annual mean speed of 4 m s -I t h e wind _2 _2 ), giving 652 KWhm per year. But most modern

(W m

w i n d m i l l s have a hub height of 5 m, w h i c h contribute

to raise the 4 m/s 2 and

speed to 5 m/s in Iraq.

This will give power density of 145.47 W m 2 w h o l e year value of 1274 K W h m - , The turbine w i n d power P is P

=

C

1

0 AV 3

(11

a)

P~ Where However,

for

P

~

Cp i s

the

most

0.250

m

co-efficient

wind

turbines,

and the

A is

the

average

rotor

wind

swept

power

area.

output

V 3

is (

12 )

m

Using

Anah where a Pm

power

modern

~

the

=

height

as

25 m a n d

not

10 m,

and

confining

the

analysis

to

0.24

0.484

Where V is the average w i n d speed at I0 m height.

( 13 ) Using figure 3, Iraq

can be d i v i d e d into four regions as far as wind power density is concerned, 2 _2 _2 3.87 to 13.07 Wm ; 14.42 to 30.98 W m ; 33.36 to 60.5 Wm , and more than _2 64.20 Wm

183 Most turbines operate at a specific designed rated wind speed Vr which is (1.8 - 2.2)Vm.

The rated wind speed is that at which the turbine is

designed to deliver its maximum power. nine locations and taking Vr

=

Therefore, using figure 2 for the

(1.8 - 2.2)Vm and adjusting them to a

height of 25 m, nine different rated speeds will result. Baghdad,

8.0 in Habbania,

8.75 in Nasiriyah,

They are 9.0 in

II in Hal and I0 m s -I in Basra.

For instantaneous wind speed of very short duration,

the net wind

turbine power is: s

P

=

Where

Cp n 1 0 AV n

their output Vout,

( 14 )

is turbine efficiency.

The most modern wind turbines limit

power to a constant level for velocities above Vr and below

(Vout menas cut-out speed), but for wind speed above Vout, the machine

normally stops. 90 Km hr -I.

Vout is above 25 m s -I which is equivalent to wind speed of

This means Vr < V > Vout and when c > Vout, P = 0.

Ideally,

the factor Cp should be maximum and s

P

=

(Cp q) max i 0 AV

P

=

Constant

( 15 )

s

.V

( 16 )

Most turbine manufacturers

try to attain this condition.

The power

curve for the wind speed between Vin and Vr can take shape: linear; quadratic, cubic, or any other form. For water pumping given the relatively low wind speed in most parts of the country, waters pumpers could be applied in more areas than wind turbine. In order to evaluate the mean power density, Baghdad. Pa

Also, using the following equation: s = 0.61 n (Vn .Tn)

table 5 was prepared for

( 17 )

while the extractable power density is s

Pe

=

0.16 Cp E (V n .Tn) n

and for Cp

~

( 18 )

0.405 s

Pe

-

0.25 ~

(Vn

.Tn)

( 19 )

where Vn is the wind speed at mid interval, Tn is the number of hours corresponding to the Tn speed interval divided by the total number of hours. 2 Figure 15 shows the mean power density in Baghdad. The sum is 47.7 Wm

CONCLUSIONS Wind energy in Iraq has a very good prospect.

Iraq can be divided

into four zones, 50% of the country has an average wind speed 3.1 to 4.00 -i -I , 17% has average speed of 2.00 to 3.00 m s , and 16% of the country

m s

184 has relatively Anah,

high average

speed of greater

B a g h d a d and B a s r a a s f o u r

average

speed ranges.

equation

representative

The power i n t e n s i t i e s

13 w e r e f o u n d t o be

11.1,

14.5,

than 5.0 m s

-1

Taking Mosul.

t o w n s o f t h e f o u r Wind for

those

regions

2 8 . 9 3 a nd 4 0 . 4 Wm- 2 ,

b a s e d on respectively.

2

This

gives

an a v e r a g e

o f 3 6 . 4 Wm

Wind-power represents

15% of s o l a r

power. Wind pumping can be used anywhere in Iraq while electricity generation is cost effective in 16% of the country.

Wind farms can be installed in Anah

region to supply a reasonable surrounded area using a number of 250 Kw wind turbines, which will contribute with the other resources to meet all the present electricity demand in the country. It is clear from the various diagrams mentioned in this paper, that -i wind speed in excess of 12 m s exists sometimes in various parts of Iraq, see figure II.

Also diurnal pattern of wind speed has wind speed variation

as high as 4.0 m s-lbetween mid-day, which is the highest, and early hours of the morning as shown in figure 9. Iraq has an average wind region,

In comparison with other Arab countries,

(i0).

The mean shape parameter K and scale

parameter C for Baghdad were found to be 3.4 and 3.8, respectively,

as shown

in figure i0. For water pumping using wind turbine, a cut-in-speed of 2 m s -I a cut-out speed of 25 m s are recommended in Iraq.

-I

and

If higher cut-in speed turbines are used in Iraq, for example the case -I in figures ii and 12 which represent wind frequencies greater than 4 m s for the best year in Anah and Najaf, Anah, Baghdad, Najaf and Nasiriyah,

then the yearly densities for Mosel, 2 290, 748, 692, 1566 and 254 KWhm will

result. It was found from using figure 13 and all similar figures for the nine locations,

the average speed power densities are 29.2 for Mosel, 80.0 for

Anah, 48.84 for Rutba, 56.5 for Habbania, 51.20 for Nasiriyah,

47.75 for Baghdad, 50.20 for ~ i ,

and 57.20 Wm -2 for Basra.

It is also clear from

figure 2 that wind speed is greater than winter months.

This is very

fortunate for Iraq since energy demand during summer months due to cooling loads is much greater than winter months.

REFERENCES 1

Hamdani, N.I., Solar Radiation Measurement in Iraq, Arab Int. Solar Energy Conference, Kuwait, 2 - 8 December 1983, pp.

2

Internal Solar Energy Report, Wind Energy Feasibility Study for Pumping for Pumping for Specific Locations in Iraq, SERC, 1986, Baghdad Iraq (In Arabic)

185 Ai-Azzawi, S.I. and Zekl, N.A., Comparison between the Characteristics of Wind Power Calculations and Solar Radiation Energy of some Meteorological Stations in Iraq. Journal of Solar and Wind Technology (in press) Anon., Iraqi Met. Office, Report No. 15 (1960 - 1970) Lysen, H., Introduction to Wind Energy, Consultancy Services, Wind Energy, Developing Countries (CWD), 82-i, May 1983, 2nd Edition, The Netherlands. 6

Johnson, G.L., Wind Energy Systems, Prentlce-Hall, Inc. 1985, New Jersey.

7

Stevens, M.J.M., The Estimation of the Parameters of the Weibull Wind Speed Distribution for Wind Energy Utilization Purposes. Wind Engineering, 3, 2, 1979, 132 -145. Weibull, W., Statistical Distribution Function of Wide Applicability, Report No 51-A-6, Stockholm, Sweden, 1951. Musgrove, P.J., Wind Energy Conversion: Recent Progress and Future Prospects, Jounral of Solar and Wind Technology, Vol. 4, No. I, 1987 pp 37 - 50.

I0

Sayigh, A.A.M., The Potential of Wind Energy in the Arab World, European Wind Energy Conference, Rome, Italy, 7 - 9 September 1986

186

TU

KEY

T

%

Flg

II

o

) Selected

stations

in

JR^O.

fl 9

{2

] Thl

overagl

~totton~

wind

in

Spele

[RAQ,

for

~mlected

1960-1970,

URK E Y

,,2

t

Lu

~u co .c

Z

LU

>

i

i

J

f

M

^

1,4 J

J

^

5

0

N

I[]

MQNTH Fig

~

,~.oo .,.J

Fi 9

( ~

(

speecls

I R, g l o t ~ a l

dl@frlbutlen IRAQ.

of

wind ~plad~ I n

4" ] T h e monthly overage or ~aghdad ( 1960-19701

mgon

3500

v

=

3,91

Im/~l

3000

T tOO

Z o rr w O_ ~q O~

~L~

2O0O

50 D 0

0 -r

I

¢

2

6

SPEED

8 IN

IO

fO00

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2

3

4

S

W~N0 5 P E E O

Fig

wind

( 5

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Wind

~p~d

5aghdad

frequqncy

I~65.

data

at

Fig

( 6

IThG dora

overogt ot

6

7

tm/~l

~peld

frequency

~aghd~d 1 1 ~ 6 0 ~ 1 ~ 7 0 ) .

187

7 6

II %, E Z

4

0 W W Q.

3 2 I

0 0

2

4-

6

B

10

(Zi,IULATIVE 01JRATION I N HOURS I Tho~,lsqnds I rig

( TIThe

duration

for

dl;trlbutlon

Baghdad

curve

11960-70l.

0 "r

6

Z

IAI

(BI 12

Z

o

1O

~

6

4 3

>~_

~-

'

0

0

,

i

.

,

Z

4-

6

B

I

.

4

< J

2

o

0

10

l

0

CUMULATIVE OURATION IN HOURS | Thoud;and~; I Flgl B I Hlgtograms of the the cumulative distribution

2

3

#

W]NO SPEED

duration I~1 a t

5

6

Im/6 I

dl¢trlbutlon IA}. Baghdad |1~60-701.

and

7 6

\ E

--

5

O LU LIJ

4

m

3

Q Z

2

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E

i 0

3

6

9

12

15

2000

0 5

18 21

6

?

0

g

I0 I I

I IZ

I 13

14

.. 15

WlNO SPEEJ~ IN m/. TIME

IN

HOURS Fig

Fig( speed

9 ] at

Diurnal Baghdad

pattern In

the

of month

the June

wind 1965.

( IO ! T h l

frequency

~f wind i p l e d

g t NAJAF I n 19"/0,

)** m/!

188

3000 <

2,0

2000 o S j 2 t

~.O

e 2.0

I000

Ln

5 = {V) "

~~LI

o I

,5 5

6

"7 B

9

WIND SPEED

Fig

(II}

>4.00

m/~

frequency ot

ANAH

~ -2.1

10 I I 12 13 14-

of

I N m/~;

wind

-3.

I

-4.,

speed

F~g

t 2 ) The ob6erved values of L n l - L n l l - ~ l v l l ) plottld

1970.

iglinst

Ln (V}.

~ 0.4 u O.3 d H 0.2

We~bull O l s t r l b u t i o n K-2,06 Actual data

m

2.0 Flg

{

13 } Wetbull

4.0 5.0 WIND SPEED m/~, distribution

for

8,0

t2.0

10.0

Baghdad June (1965]

.

0 6.0 ~5 E L

I '~, rajah ._,-~,~c__~" .......

o-

c

/

j ....

5 . =,

C

//^\~ 4.0

5.0

\

~_~___

3.5 Qo l

,0

I ~

Z.5

1 9 6 0 61 6 2

Fig

[1¢

]

Annual

value~

of

Weibull

the

63

of

64

65

the

66 67

shape

distribution

a --

68

69

and for

4.5

"o Q

4.0

g

,5.5

~

3.0

~

70

~cale Baghdad

poram¢ters 1960-70.

ire

189

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STATION

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MID-POINT

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(

I~

)

Mean

power

speed

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WIND

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36

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445

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(1960-1970].

III

17

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data

G*ographlcol

;elected

lm/l I

33

33

l

Table

INTERVAL

HEII~ IMI

I~IRIA

7

versus

I.ONI; I ~

+

SPEED I m / ~ l

density

LATITUDE

for

;totlon;.

OUP.AT 10N

(b I

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+

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Ir

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A

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J

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0

13

13

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13

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13

13

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13

16

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13

20

16

13

20

43

16

13

13

Z0

10

13

Z3

16

b6

16

13

16

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TOTAL.

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+59

is-i

0

T a b l e t z i Th* v * l o c l l ? frlguen¢y data of ~uhdad tJ960-701.or* tr,.,~orm.~ I, a Vurltlon dl+trl),~+on ond • m~lotlv, dl+trI~tl+~ ,Th* ~pplr bo~nd+ry 11 the Interval I+ Indicated my U v .

Tabl*

13

. + =

....

?o

16

zol6

Tabl+

. . . . . . . . . . . . . . . . . .

[ 3 ) Thl

m*fhod . ×1

for

Y

PI W)

F'(VI

1.0

0.04-6

0.04`6

0,0

-3. 056

2.0

0.046

0.092

0,6931

-2,330

3.0

0,154

0.246

1.0'986

-~ . Z 6 5

4,0

0.14-2

0.3638

1,386

-O,71IZ

5.0

0 . 14-2

0.53

I ,61

-O.ZSI

6.0

O. I

0.63

I .792

-0.0057

Ya

7.0

O , 12

0.75

I .94-6

0.3266

8.0

O. It7

0.B67

2.00

0.7

9.0

0.06

0.93

2. 197

0.96

I0+0

0.04"2

0.g69

2.30

I .24`5

I 1.0

0.0~'1

0.~

2,398

I .S27

12.0

0.004`2

0.994-1

2.4`aS

1.64

13,0

0.0009

0,~51

Z.~5

1.67

Xl

= I-nlVl

YI

= L.nl-~.z~lI-P'lV))

16

moxl~m

t IS~O-I~OI

I~l. R e w u l t for the LaD CSouh d a d -.£k~n I I I ~ )

ZO

13

wind

t6

16

Ipt4d

16 , io

In

13

/~noh

2o

In

m/l*

the