Wind Energy

Abstract: While we are running out of our energy sources, the consequences of our modern day living are increasingly becoming alarming. Wind is on the cusp of becoming a major source of electricity around the world, Wind is widely available around the world This paper elucidates about wind Energy ,a brief discussion of its development is presented, and the operating and design principles are discussed. Alternative designs for wind turbines and the tradeoffs that must be considered are briefly compared. Development of a wind energy system and the impacts on the utility network and power quality are discussed.

Introduction:

Basically the energy sources are two types; they are conventional energy sources like coal, petroleum, natural gas etc. & non-conventional energy sources like solar cells, fuel cells, thermo-electric generator, thermion converter, solar power generation, wind power generation, geo-thermal energy generation, tidal power generation etc. Fast depletion of conventional energy sources made us to look after alternate energy sources. The non-conventional or renewable energy sources  naturally replenished thus it will not be exhausted contrary to the conventional energy sources which have an expiry date.Wind Energy is the energy produced from the wind blow.
 Airflows can be used to run wind turbines. The power available from the wind is a function of the cube of the wind speed, so as wind speed increases, power output increases dramatically up to the maximum output for the particular turbine. Areas where winds are stronger and more constant, such as offshore and high altitude sites, are preferred locations for wind farms.

Wind turbines:

A wind turbine is a device that converts kinetic energy from the wind, or wind energy into mechanical energy. the process known as wind power. If the mechanical energy is used to produce electricity, the device may be called wind turbine or wind power plant.Wind turbines can be installed as single installations or as part of a wind farm .

Different types of wind turbines:

There are two main types of wind turbines, horizontal and vertical axis.

Horizontal axis

Horizontal axis wind turbines are the most common type used (see figure 1). All of the components (blades, shaft, generator) are on top of a tall tower, and the blades face into the wind. The shaft is horizontal to the ground. The wind hits the blades of the turbine that are connected to a shaft causing rotation. The shaft has a gear on the end which turns a generator. The generator produces electricity and sends the electricity into the power grid. The wind turbine also has some key elements that adds to efficiency. Inside the Nacelle (or head) is an anemometer, wind vane, and controller that read the speed and direction of the wind. As the wind changes direction, a motor (yaw motor) turns the nacelle so the blades are always facing the wind. The power source also comes with a safety feature. In case of extreme winds the turbine has a break that can slow the shaft speed. This is to inhibit any damage to the turbine in extreme conditions.

Advantages
• Blades are to the side of the turbines center of gravity, helping stability
• Ability to wing warp, which gives the turbine blades the best angle of attack
• Ability to pitch the rotor blades in a storm to minimize damage
• Tall tower allows access to stronger wind in sites with wind shear
• Tall tower allows placement on uneven land or in offshore locations
• Can be sited in forest above tree-line
• Most are self-starting
Disadvantages
• Difficulty operating in near ground winds
• Difficult to transport (20% of equipment costs)
• Difficult to install (require tall cranes and skilled operators)
• Effect radar in proximity
• Local opposition to aesthetics
• Difficult maintenance

Vertical axis
In vertical axis turbines the shaft the blades are connected to is vertical to the ground (see figure 2). All of the main components are close to the ground. Also, the wind turbine itself is near the ground, unlike horizontal where everything is on a tower. There are two types of vertical axis wind turbines; lift based and drag based. Lift based designs are generally much more efficient than drag, or ‘paddle’ designs.

Advantages
• Easy to maintain
• Lower construction and transportation costs
• Not directional
• Most effective at mesas, hilltops, ridgelines and passes
Disadvantages
• Blades constantly spinning back into the wind causing drag
• Less efficient
• Operate in lower, more turbulent wind
• Low starting torque and may require energy to start turning.

Three bladed wind turbine:

Three bladed propeller deign has evolved as the commercial Wind Energy Conversion System today.

Floating Wind Turbines

Floating wind turbines are one promising technology getting a lot of attention now. Because they are in a nascent stage, we’re just looking to discuss these over in the Technology section for now. But the huge promise of this technology is that it allows turbines to be placed in deeper waters where wind is stronger and more consistent.

 

A new floating wind turbine from Altaeros Energies is able to generate more energy  by harnessing higher altitude winds, and could be used at remote sites.
The turbine is contained within an inflatable tube-shaped shell filled with helium, with allows it to rise to the strong winds at high altitudes while remaining tethered to the ground. Besides harnessing more powerful winds, the turbine is also very quiet to run and requires little maintenance.

Wind energy --World

“The wind power market value is expected to grow from €66.8 billion [$96.4 billion] in 2011 to €111.7 billion [$161.2 billion] in 2015,” according to International Wind Energy Development – World Update 2010Wind Today Report. By the end of 2011, wind power is projected to supply the world with 1.92% of its electricity. By 2020, wind power is expected to produce 9.1% of the world’s electricity demand. “Looking forward, the report projects an average global growth rate of 15.5% per year for new annual installations through 2015, resulting in expected total global capacity of 513.6 GW by 2015.” (Note that 1,000 MW = 1 GW.)

Advantages of wind energy:

1.The wind is free and with modern technology it can be captured efficiently.2. Once the wind turbine is built the energy it produces. 

does not cause green house gases or other pollutants.
3. Although wind turbines can be very tall each takes up only a small plot of land. This means that the land below can still be used. This is especially the case in agricultural areas as farming can still continue.
4. Many people find wind farms an interesting feature of the landscape.
5. Remote areas that are not connected to the electricity power grid can use wind turbines to produce their own supply.
6. Wind turbines have a role to play in both the developed and third world.
7. Wind turbines are available in a range of sizes which means a vast range of people and businesses can use them. Single households to small towns and villages can make good use of range of wind turbines available.

Disadvantages of wind energy:

1 The strength of the wind is not constant and it varies from zero to storm force. This means that wind turbines do not produce the same amount of electricity all the time. There will be times when they produce no electricity at all.
2. Many people feel that the countryside should be left untouched, without these large structures being built. The landscape should left in its natural form for everyone to enjoy.
3. Wind turbines are noisy. Each one can generate the same level of noise as a family car traveling at 70 mph.
4. Many people see large wind turbines as unsightly structures and not pleasant or interesting to look at. They disfigure the countryside and are generally ugly.
5. When wind turbines are being manufactured some pollution is produced. Therefore wind power does produce some pollution.
6. Large wind farms are needed to provide entire communities with enough electricity.