Wind Energy Arthur Dzhafarov Kirill Balmassov Zengjun Chen Xiaofeng Li

Outline What is Wind? Basic technologies of Wind Power Classification of winds Types of winds Wind measurement Wind Speed & Direction Basic technologies of Wind Power The usage and potential of Wind power Pros and Cons of Wind energy Conclusions

What is Wind? A «wind» is simply the flow of a huge amount of air, usually from a high pressure-area to a low-pressure area. Wind is the flow of gases on a large scale. On the surface of the Earth, wind consists of the bulk movement of air. Winds are commonly classified by their spatial scale, their speed, the types of forces that cause them, the regions in which they occur, and their effect. How is wind formed? Typically, this begins with the sun’s radiation, which is absorbed differently on the earth’s surface. The earth's surface is heated differently because of scenarios like cloud cover, mountains, valleys, water bodies, vegetation and desert lands. As a result of this uneven heating, there are bound to be earth surfaces that vary a lot in temperature. Air on surfaces with higher temperatures will then begin to rise because it is lighter (less dense). As the air rises, it creates low atmospheric pressure. The sinking creates higher atmospheric pressure. This behaviour or warm gases or liquids moving upward and being replaced by cooler particles is called Convection. The energy moving during convection is called convectional current.

Let us see this illustration below showing pressure and wind direction: In the diagram above, notice how cool air falls, resulting in high pressure, and moving towards regions of low pressure Anywhere and each time there are differences in atmospheric (air) pressure, there will be a wind, because air will move from the high-pressure area to the low-pressure area. It also means that winds may be even stronger where the difference in the air pressure is greater. A good example is how tropical depression forms, where warm air over hot tropical waters rise, and high-pressure cold air quickly rushing to fill the space.

Classification of winds Winds may be calm, gentle, moderate, strong or gale. Some countries have slightly different names for each of them, and some even have more classifications between each. Let us look at these 5 basic classes. Calm air These are generally felt as an airy condition. This class is not enough, even to fly a feather kite. It is also called light wind, and it has a speed of about 1km/hr. Calm air will be noticed by smoke rising vertically from a chimney. They have a Beaufort Number 0. Gentle Breeze Gentle breezes have speeds of about 12-20km/hr. They are called Gentle-Moderate Winds. Leaves and small twigs would be constantly moving with gentle breezes. They have a Beaufort Number 3. Moderate winds Moderate winds have speeds of about 20-38km/hr. They are enough to fly a kite and keep it going higher and higher. They can cause moderate waves with on the sea and make trees whistle.

Strong winds Gale winds Strong winds are also called Gale. They have speeds of about 62-74km/hr. They can cause high waves over the seas and break off twigs and small branches from trees. They have a Beaufort number of 8. Gale winds Gale winds have speeds of about 75km/hr and more. They can be very destructive and they carry lots of broken branches and twigs from trees. They cause high tidal waves and rolling seas. They can also rip off roofs of building. Gale winds that progress end up as tornadoes and hurricanes, even though they are formed differently.

Types of winds Local Winds Global Winds Local winds are those that are created as a result of scenery such as mountains, vegetation, water bodies and so on. They can move from mild to extreme winds in just hours. Good examples of local winds are sea breezes and land breezes, and mountain and valley breezes. Local winds cover very short distances. Above are some standard wind belts with the white arrows showing the direction of winds, red arrow showing vertical rising air, and blue arrow showing cold sinking air Global Winds Global winds are really large air masses that are created mainly as a result of the earth’s rotation, the shape of the earth and the sun’s heating power.

Hurricane fact Doldrums: This is the very low pressure area along the equator where prevailing winds are calmest. This low-pressure area is caused by the constant heating of the sun. This belt extends to about 5° north and south of the equator. Hurricane fact Tropical Easterlies (Trade Winds): This is the belt extending as far as 30° north and south latitude of the Inter-tropical Convergence Zone (ITCZ). Hurricane fact Horse Latitudes: This is wind belt that forms at about 30° north and south latitude between the trade winds and the prevailing Westerlies. Hurricane fact Prevailing Westerlies: This is the belt extending from 30° to 60° latitude from the ITCZ. Hurricane fact Polar Easterlies: This belt covers from 60° latitudes to the north and south poles.

Wind measurement Anemometers The Weather Vane Winds come in all directions or speeds. They are measured by their directions and speeds. Depending on the cause of the winds, they can blow in many directions. Anemometers Anemometers measure the direction of winds. They come in different models but use a similar principle — cups on a bar! The speed of the rotating cups is measured by a speedometer. The measurement of wind speed is usually done using a cup or propeller anemometer, which is an instrument with three cups or propellers on a vertical axis. The force of the wind causes the cups or propellers to spin. The spinning rate is proportional to the wind speed. The Weather Vane Another instrument in wind measurement is the wind vane. It involves a pointer mounted on a vertical shaft. When the wind blows, the arm sways until the pointer faces the direction of the wind. Wind is caused by difference in air temperature and variations in pressure. Wind direction is measured by a wind vane that aligns itself with the direction of the wind

Wind Speed & Direction What are wind speed and direction? Wind speed describes how fast the air is moving past a certain point. This may be an averaged over a given unit of time, such as miles per hour, or an instantaneous speed, which is reported as a peak wind speed, wind gust or squall. Wind direction describes the direction on a compass. Wind speed and direction are how fast the air is moving and from which direction. Why are wind speed and direction important? Wind speed can be reported in miles per hour, meters per second, or knots. Wind direction is reported in degrees. Wind speed and direction are important for monitoring and predicting weather patterns and global climate. These parameters affect rates of evaporation, mixing of surface waters. Wind speed and direction play a large role in predicting weather patterns.

Historical retrospection For thousands of years people have tried to make the wind their ally. They used it in order to propel wind mills, to sail boats and to move objects and vehicles. That is to produce energy The first automatically operated wind turbine, built in Cleveland in 1887 by Charles F. Brush. It was 60 feet (18 m) tall, weighed 4 tons (3.6 metric tonnes) and powered a 12kW generator

How Wind Power Is Generated? The terms "wind energy" or "wind power" describe the process by which the wind is used to generate mechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity.

How do wind turbines make electricity? A wind turbine works on a simple principle. Energy in the wind turns two or three propeller-like blades around a rotor. The rotor is connected to the main shaft, which spins a generator to create electricity. Wind turbines are mounted on a tower to capture the most energy. At 30 meters or more above ground, they can take advantage of faster and less turbulent wind. Simply stated, a wind turbine is the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity.

Wind turbine components The wind turbine constructed from next components: Blades lifts and rotates when wind is blown over them, causing the hub to spin. Blades and hub formed rotor Pitch system turns blades out of the wind to control the rotor speed, and to keep the rotor for turning in winds that are too low or too high to produce electricity Emergencie brake Gear box connects the low-speed shaft to the high-speed shaft and increases the rotation sppeds. Generator produces electricity controller decide when turbine must to work and when it must to stop depends in wind speed. Anemometer for measuring of wind speed Wind vane measures wind direction and communicates with the yaw drive to orient the turbine properly with respect to the wind. yaw drive and yaw motor orient the turbine.

Types of Wind Turbines HAWT VAWT Modern wind turbines fall into two basic groups: the horizontal-axis variety and the vertical-axis design, like the eggbeater-style Darrieus model.

Advantagdes and disadvanteges of HAWT ant VAWT HAWT adv. Higher efficiency Higher speed of rotation disadv. Massive tower construction is required Difficult instalation Need additional devices Disturb view of landscape VAWT adv. No yaw mechanisms is needed. it easier to maintain have lower wind startup speeds disadv. lower efficiency rotors located close to the ground The tall tower base allows access to stronger wind in sites with wind shear. In some wind shear sites, every ten meters up the wind speed can increase by 20% and the power output by 34%. High efficiency, since the blades always move perpendicularly to the wind, receiving power through the whole rotation. In contrast, all vertical axis wind turbines, and most proposed airborne wind turbine designs, involve various types of reciprocating actions, requiring airfoil surfaces to backtrack against the wind for part of the cycle. Backtracking against the wind leads to inherently lower efficiency. disadv. Massive tower construction is required to support the heavy blades, gearbox, and generator. Components of a horizontal axis wind turbine (gearbox, rotor shaft and brake assembly) being lifted into position. Their height makes them obtrusively visible across large areas, disrupting the appearance of the landscape and sometimes creating local opposition. HAWTs require an additional yaw control mechanism to turn the blades toward the wind. HAWTs generally require a braking or yawing device in high winds to stop the turbine from spinning and destroying or damaging itself. adv. No yaw mechanisms is needed. A VAWT can be located nearer the ground, making it easier to maintain the moving parts. VAWTs have lower wind startup speeds than the typical the HAWTs. VAWTs may be built at locations where taller structures are prohibited. VAWTs situated close to the ground can take advantage of locations where rooftops, mesas, hilltops, ridgelines, and passes funnel the wind and increase wind velocity. Most VAWTs have a average decreased efficiency from a common HAWT, mainly because of the additional drag that they have as their blades rotate into the wind. Versions that reduce drag produce more energy, especially those that funnel wind into the collector area. Having rotors located close to the ground where wind speeds are lower and do not take advantage of higher wind speeds above.

Technical innovations Self-erecting module Modular blade For cost reducing of instalation, developed modular blades and self-erecting towers. And blabla bla….

The usage and potential of wind power

How wind turbine works Wind turbines can convert the mechanical power that used for a variety of activities like pumping water. Wind turbines can also use generators to convert wind energy into electricity.

Typical Wind Turbine Operation 0 ~ 10 mph --- Wind speed is too low for generating power. Turbine is not operational 10 ~ 25 mph --- 10 mph is the minimum operational speed. It is called “Cut in speed”. In 10 ~ 25 mph wind, generated power increases with the wind speed. 25 ~ 50 mph --- Typical wind turbines reach the rated power (maximum operating power) at wind speed of 25mph (called Rated wind speed). > 50 mph --- Turbine is shut down when wind speed is higher than 50mph (called “Cut-out” speed) to prevent structure failure.

Betz Limit The wind turbine extracts energy by slowing the wind down. The theoretical maximum amount of energy in the wind that can be collected by a wind turbine's rotor is approximately 59.3%. This value is known as the Betz limit. If the blades were 100% efficient, a wind turbine would not work

Optimization of wind turbine Doubling the tower height increases the expected wind speeds by 10% and the expected power by 34%. Doubling the tower height generally requires doubling the diameter. Tower heights approximately two to three times the blade length have been found to balance material costs of the tower .

Wind Power Global Capacity and Annual Additions, 2005–2015

Wind Power Capacity and Additions, Top 10 Countries, 2015

Example Residential Wind Turbine The output from the GridTek can be connected to the home or business circuit breaker panel by using an inverter. Operation of the system is fully automatic. It has a rotor diameter of 23 feet and is typically installed on 80 or 100 foot towers.

(A) Onshore (B) Offshore Annual wind energy potential

Benefits for environment •No carbon dioxide emission during operation •High energy harvest factor without using any fuel during the operating life of the power plant •No fuel spillage •No waste – more than 80% of a wind turbine may be recycled •Low price of dismounting wind turbines to recover initial landscape compared to other sources of energy

Political aspects of wind energy • Free and renewable • No military protection needed of energy supplies • No public health damage • Labour intensive – higher employment than conventional form of energy • Local rural job creation for transport, installation and maintenance • Most rapid instalment of all electricity generation technologies • Cheapest renewable energy source, competitive with most new power generation sources • Fixed lifetime cost – no sensitivity to rising and variable fuel prices • Compatible with traditional soil use (agriculture, livestock, etc.)

Technological aspects - Maturity • Most initial operational problems is now solved -Reduced weight and price of the blades, and increased robustness by the using composites in the manufacturing -Lightning and fire protection by passive and active systems -Comparable effective and robustness components to the ones used in other technologies -Preventive maintenance by SCADA monitoring -Compatibility with weak networks and fulfilment of most demanding grid codes has been solved with the new solutions applied in the design of modern wind turbines • Operational risks is now close to zero in a wind farm project

Technological aspects – Grid Integration • Wind energy generates a high percentage of electricity consumption in several countries • Complies with the most demanding grid codes • Capable to work in weak networks • Exceptional integration with networks by technical solution such as the full converter • Wind energy production may be predicted up to 48 hours in advance. This reduces the influence of variability (not intermittency) effect on network stability. • Easily combines with other technologies to provide a complete solution for power supply in isolated areas  

Technological aspects – Challenges and solutions • Increased performance by use of new numerical techniques (e.g. massive computer fluid dynamics (CFD) is used to analyse more in detail the flow field around the wind turbine). • Detailed Analysis of Atmospheric Boundary Layer will increase wind prediction capability • New sensors will allow the use of adaptive control systems. Wind turbines will respond according to local conditions.

Cons - wind energy •Premium Onshore sites saturated •Offshore towers more expensive •Cause Noise pollution •Lots of wind turbines are needed to produce enough power •Turbines can only be put in windy areas •It is not always windy

Conclusions - wind energy https://www.youtube.com/watch?v=lLqF8LliTTI

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