Khaled Daoud
Wind Energy Division
National Energy Research Center
Jordan Engineers Association
March 29, 2012
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ENERGY RESOURCES
The World’s Energy Resources Are Limited!
Conventional Energy Resources
o Oil
o Coal
o Natural Gas
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March 29, 2012
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Renewable Energy Sources
Wind
Water
Renewable Energy
Sources
Biogas
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Solar
Geothermal
Biomass
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SOLAR
Renewable Energy Sources
Geothermal
Wind
G
T
Generator
Transformer
Distribution
Lines
Your Home
All renewable energy, ultimately
come from the sun.
Biomass
Water
Biogas
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March 29, 2012
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Why Renewable Energy?
The growth of energy demand
Fast depletion of fossil fuel.
Global environmental problems.
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RENEWABLE ENERGY
• Renewable energy resources may be used directly
Or indirectly to create other more convenient forms
of energy.
• Examples of direct use are solar ovens, geothermal
heating, and water heating and water pumping by
windmills.
• Examples of indirect use which require energy
harvesting are electricity generation through wind
turbines or photovoltaic cells, or production of fuels
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Wind Energy Resource
• Wind energy is a sub-product
of solar energy
• Earth receives 1.74 x 10 17 W
of solar energy - 2% of it is
transformed to winds
• Wind energy is the kinetic
energy of the moving winds
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March 29, 2012
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Wind Energy Resource
 Reason: unevenly radiation of earth surface by the sun
 The regions around equator, at 0° latitude, are heated
more by the sun than the rest of the globe
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Wind Energy Resource
 Hot air is lighter than cold and will
rise into the sky until it reaches
approximately 10 km altitude and will
spread to the North and the South. If
the globe did not rotate, the air would
simply arrive at the North Pole and
the South Pole, sink down, and return
to the equator
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March 29, 2012
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Wind Energy Resource
The Coriolis force
 Due to the earth rotation, any movement on
the Northern hemisphere is diverted to the
right (left in the southern) if we look at it from
our own position on the ground.
 Named
after the French mathematician
Gustave Gaspard Coriolis 1792-1843
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March 29, 2012
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Wind Energy Resource
Global winds and Coriolis force
 The wind rises from the equator and moves
north and south in the higher layers of the
atmosphere.
 Around 30° latitude in both hemispheres the
Coriolis force prevents the air from moving
much further. At this latitude there is a high
pressure area, as the air begins sinking
down again.
 As the wind rises from the equator there will
be a low pressure area close to ground level
attracting winds from the north and south.
 At the poles, there will be high pressure due
to the cooling of the air.
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March 29, 2012
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Wind Energy Resource
The geostrophic wind
 The global winds are the geostrophic winds. They are largely driven
by temperature (pressure) differences and are not very much
influenced by the surface of the earth. Geostrophic winds are found
at altitudes above 1 km above ground level.
Surface winds
 Winds are very much influenced by the ground surface at altitudes
up to 100 metres. The wind will be slowed down by the earth's
surface roughness and obstacles. Wind directions near the surface
will be different from the direction of the geostrophic wind because
of the earth's rotation (i.e. Coriolis force).
When dealing with wind energy, we are concerned with surface winds,
and how to calculate the usable energy content of the wind.
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Wind Energy Resource
Surface Winds: Sea Breeze
 Land masses are heated by the
sun more quickly than the sea
during daytime. The air rises,
flows out to the sea, and
creates a low pressure at
ground level which attracts the
cool air from the sea.
 At nightfall there is often a
period of calm when land and
sea temperatures are equal.
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March 29, 2012
Monsoon
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Wind Energy Resource
Surface Winds: Land Breeze
 At night the wind blows in
the opposite direction.

The land breeze at night
generally has lower wind
speeds,
because
the
temperature
difference
between land and sea is
smaller at night.
The monsoon known from South-East Asia is in reality a large-scale
form of the sea breeze and land breeze, varying in its direction between
seasons
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March 29, 2012
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Wind Energy Resource
Surface Winds: Mountain Winds
 They originate on south-facing
slopes (north-facing in the southern
hemisphere). When the slopes and
the neighbouring air are heated the
air ascends towards the top following
the surface of the slope. At night the
wind direction is reversed.
•Foehn in the Alps in Europe,
•Chinook in the Rocky Mountains
•Zonda in the Andes.
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March 29, 2012
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Wind Energy Resource
Local winds:
 Mistral flowing down the Rhone valley
into the Mediterranean Sea,
 Scirocco, a southerly wind from Sahara
blowing into the Mediterranean sea.
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March 29, 2012
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Wind Energy Resource
Wind systems in the Mediterranean sea region
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March 29, 2012
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Wind Energy Resource
Atmospheric boundary layer
 At 1 km above ground level, the wind is not influenced by
the surface of the earth at all (geostrophic winds).
 In the lower layers of the atmosphere, however, wind
speeds are affected by the friction against the surface of
the earth.
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March 29, 2012
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Wind Energy Resource
 Friction is created due to the roughness of the terrain and
the influence of obstacles
 Forests and large cities slow the wind down considerably
 Concrete runways in airports slow the wind down a little.
 Long grass and shrubs and bushes slow the wind down
considerably.
 Water surfaces are even smoother have even less
influence on the wind
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March 29, 2012
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Wind Energy Resource
Effect of Obstacles
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Wind Energy Resource
Effect of Obstacles
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March 29, 2012
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Wind Energy Resource
Affecting the wind:
Temperature
Roughness
Obstacles
Orography
Meteorology
Thermals
wind from sea
sea
beach
grass
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trees
hills
woods
March 29, 2012
buildings cities valleys & mountains
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Wind Resource Assessment
1. The Power in the wind is proportional to Cube of the wind
speed (10% difference in wind speed makes about 33%
change in wind power). This is the primary reason for
wind resource assessment.
2. Wind speed, wind shear*, turbulence** and gust intensity
all need to be specified when procuring a wind turbine
and designing its foundation….etc.
3. Turbine manufacturers concerns max. turbulence
intensity (16%), max. wind shear acting on blade area
(0.2) and max. one second gust used for foundation
design
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March 29, 2012
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Wind Resource Assessment
* Wind shears (large differences in the mean wind speed
over the rotor) give large fluctuating loads and consequently
fatigue on the wind turbine blades, because the blades move
through areas of varying wind speed.
** Turbulence causes dynamic loads on wind turbines. The
strength of the turbulence varies from place to place. Over
land the turbulence is more intense than over the sea
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March 29, 2012
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Wind Resource Assessment
Without wind resource , no wind project will even be viable.
Wind Resources assessments are the
cornerstone
of
identifying
and
mitigating risks and for realizing the
potential rewards from a project.
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March 29, 2012
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Wind Resource Assessment
Site Visits and Evaluations
•Visits should be conducted to all suitable areas with the main goals
of verifying site conditions.
The evaluator should use the following:•
•
•
•
The site topographical map
A Global Positioning System (GPS)
A Camera
A compass
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March 29, 2012
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Wind Resource Assessment
Preliminary Area Identification based on information such
as :
• previous wind data,
• Topography,
• Flagged trees ..etc.
A new wind measurement sites can be selected.
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March 29, 2012
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Wind Resource Assessment
Prevailing Wind Direction
Important to check direction when
setting up instrument
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March 29, 2012
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Wind Resource Assessment
Griggs – Putman Wind Index
This index is based on the permanent tree deformation caused by
wind and is useful for estimating the average wind speed in an area.
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March 29, 2012
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Wind Resource Assessment
Information in the resource assessment will include :• Daily average wind speeds
• Monthly average wind speeds
• Annual Average wind speeds
• Frequency distribution
• Wind Rose
• Wind power density
• Turbulence intensity
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March 29, 2012
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Wind Resource Assessment
Frequency Distribution
• The basic tool for estimating energy
production.
• It shows the % of time that the wind
blowing at certain speed.
The wind speed are binned, meaning that
wind speed between
0 - 1 m/s are binned as 1 m/s,
1 - 2 m/s are binned as 2 m/s,
and so on.
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March 29, 2012
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Wind Resource Assessment
X
Frequency Distribution
X
Power Curve
Energy Production
To assess a site’s wind power production potential, the wind speed
frequency distribution must be multiplied by a representative wind
turbine power curve.
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March 29, 2012
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Wind Resource Assessment
Wind rose is a useful tool to
know the wind direction.
It is a valuable tool for project
layout and micro-siting
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March 29, 2012
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Wind Resource Assessment
Wind Power density (W/m²)
•It is defined as the wind power available per unit area
swept by the turbine blades.
•It is a true indication of wind energy potential in the site
than wind speed alone.
•Its value combines wind speed distribution and air
density.
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March 29, 2012
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Wind Resource Assessment
Wind Power Class Table
Wind
Class
Resource
Potential
Wind Power
Density
W/m²
Wind Speed
W/S
< 200
< 5.6
1
Poor
2
Marginal
200 - 300
5.6 - 6.4
3
Moderate
300 - 400
6.7 – 7.0
4
Good
400 – 500
7.0 - 7.5
5
Very Good
500 - 600
7.5 – 8.0
6
Excellent
600 - 800
8.0 - 8.8
7
Outstanding
> 800
> 8.8
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March 29, 2012
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Wind Resource Assessment
Once this assessment is
completed, an accurate
picture of wind resource
at the site should be clear
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March 29, 2012
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Thank You
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March 29, 2012
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