Wind energy resources

1. Lecture 4-5
WIND POWER GENERATION

2. WIND ENERGY
• Wind power is a type of energy conversion in which turbines transform
wind kinetic energy into Mechanical and then to Electrical Energy.
• Wind energy is the most established and mature renewable energy source.
It creates electricity by using the kinetic energy created by the influence of
air currents. It is a clean and renewable energy source that decreases
greenhouse gas emissions and protects the environment.

3. THE ORIGIN OF WIND
• The radiation energy which hits the earth, warms the earth very
differently depending on the incidence angle and the surface
finish of the ground. This is the reason for the differences in
temperature between the Polar Regions and the equator. These
temperature differences results in differences in air pressure
because heated air has a lower density than cold air. These
differences in air pressure are compensated for through the
movement of air masses. This air movement is called wind: air
from the high pressure region streams into the low pressure
region.

4. WORKING PRINCIPLE
• At it’s simplest, the wind turns the turbine’s blades, which spin a
shaft connected to a generator that makes electricity. Large
turbines can be grouped together to form a wind power plant,
which feeds power to the electrical transmission system.

5. BASIC COMPONENTS OF WIND
TURBINE
• ROTOR
• BLADES
• TOWER
• NACELLE
a) DRIVE TRAIN
b) GEAR BOX
c) YAW MECHANISM
d) GENERATOR

6. BASIC TERMINOLOGIES USED IN WIND TECHNOLOGY
• HUB HEIGHT: It is the distance between the center
of the turbine and the ground.
• TOTAL HEIGHT: If we draw a circle around the
blades of the turbine, the total height is the
distance between the top of the circle and the
ground.
• ROTOR DIAMETER: If we draw a circle around the
blades of the turbine, rotor diameter is the
diameter of that surrounding circle.
• TIP SPEED RATIO: It is defined as the ratio of the
outer blade tip speed to the unperturbed wind
speed.
• TOWER: It is the vertical supporting structure on
which whole of the turbine is mounted.

7. BASIC TERMINOLOGIES USED IN WIND TECHNOLOGY
• Drag Force 𝑭𝑫 is the component in line with the relative velocity 𝑽𝒓
• Lift Force 𝑭𝑳 is the component perpendicular to 𝑭𝑫.
• SOLIDITY: Solidity is defined as “the ratio of the total area of the blades at
any one moment in the direction of the airstream to the swept area across
the airstream”. Thus, with identical blades, a four bladed turbine presents
twice the solidity of a two bladed turbine.

8. TYPES OF WIND TURBINES
There are two main types of
wind turbines:
1. Horizontal Axis Wind
Turbine (HAWT)
2. Vertical Axis Wind
Turbine (VAWT)

9. HORIZONTAL AXIS WIND TURBINE
Turbines in which the axis of
rotation is horizontal with
respect to ground i.e. the
rotating shaft is parallel to the
ground and the blades are
perpendicular to the ground. In
HAWT, the dominant driving
force is lift. Modern HAWTs
usually feature rotors that
resemble aircraft propellers,
which operate on similar
aerodynamic principles.

10. VERTICAL AXIS WIND TURBINE

11. VERTICAL AXIS WIND TURBINE

12. VERTICAL AXIS WIND TURBINE
 Savonius rotor (turbo machine): There is a complicated motion of the
wind through and around the two curved sheet airfoils. The driving
force is principally drag. The construction is simple and inexpensive.
The large solidity produces large starting torque, so Savonius rotors
are mostly used for water pumping.
• Darrieus rotor: This rotor has two or three thin curved blades with an
airfoil section. The rotor shape is a catenary, with the aim of the
rotating blades being only stressed along their length.
• Musgrove rotor: The blades of this form of rotor are vertical for
normal power generation, but tip or turn about a horizontal point for
control or shutdown.
• Evans rotor: In this case, the vertical blades change pitch about a
vertical axis for control and failsafe shutdown.

13. ADVANTAGES/ DISADVANTAGES OF VAWT

14. ENERGY EXTRACTION FROM WIND
Betz Criterion
FOR Max Cp
value: a=1/3
and Cp = 0.59

15. TORQUE CALCULATION

16. APPLICATIONS OF WIND ENERGY TECHNOLOGY
a) Generating electricity.
b) Milling grain.
c) Pumping water.
d) Powering cargo ships (via kites)
e) Reducing carbon footprint.
f) Sailing.
g) Windsurfing.
h) Land surfing.

17. RESEARCH BASED PROJECT
• KYUSHU UNIVERSITY JAPAN
“WIND LENZ TECHNOLOGY” Wind lens is a new type of wind
power system consisting of a simple brimmed ring structure that
surrounds the rotor causing greater wind to pass through the
turbine. As a consequence, the turbine’s efficiency of capturing
energy from the wind gets dramatically increased. A Wind lens
turbine can generate 2–5 times the power of an existing wind
turbine given at the same rotor diameter and incoming wind
speed.
RESEARCH ARTICLE: Wind lens technology and its application to
wind and water turbine and beyond.

18. RESEARCH BASED PROJECT

19. MAJOR RESEARCH ASPECTS
OF WIND ENERGY
TECHNOLOGY
RECOMMENDED RESEARCH ARTICLE:
TITLE: Knowledge structure and
research progress in wind power
generation (WPG) from 2005 to
2020 using CiteSpace based
scientometric analysis.

20. TOP JOURNALS AND COUNTRIES IN WIND ENERGY TECHNOLOGY

21. WIND INSTALLED CAPACITY (2022)
FUEL INSTALLED
CAPACITY (MW)
HYDEL 10251
RLNG 9884
RFO 5958
COAL 5332
GAS 3536
NUCLEAR 3647
WIND 1985

22. CLASS QUESTIONS
• Environmental Impact of Wind Energy Technology.
• Major Advantages and Disadvantages of HAWT and
VAWT.
• Difference between HAWT and VAWT.
• Difference between On-shore and Offshore Wind
systems.