Renewable energy engineering
- 1. Subject: Renewable Energy Engineering Topic: Wind Energy
- 2. Wind Energy • All renewable energy (except tidal and geothermal power), ultimately comes from the sun. • The earth receives 1.74 x 1017 watts of power (per hour) from the sun. • About one or 2 percent of this energy is converted to wind energy (which is about 50-100 times more than the energy converted to biomass by all plants on earth). • Wind is essentially air in motion, which carries with it kinetic energy. • The amount of energy contained in the wind at any given instant is proportional to the wind speed at that instant.
- 3. Wind Energy • Winds are influenced by the ground surface at altitudes up to 100 meters. • Wind is slowed by the surface roughness and obstacles. • A wind turbine obtains its power input by converting the force of the wind into a torque (turning force) acting on the rotor blades. • The amount of energy which the wind transfers to the rotor depends on the density of the air, the rotor area and the wind speed.
- 5. Wind Energy
- 6. Vertical Axis Turbines • Advantages • Omnidirectional – Accepts wind from any angle • Components can be mounted at ground level – Ease of service – Lighter weight towers • Can theoretically use less materials to capture the same amount of wind • Disadvantages • Rotors generally near ground where wind poorer • Centrifugal force stresses blades • Poor self-starting capabilities • Requires support at top of turbine rotor • Requires entire rotor to be removed to replace bearings • Overall poor performance and reliability • Have never been commercially
- 7. Number of Blades • Most common design is the three-bladed turbine. The most important reason is the stability of the turbine. A rotor with an odd number of rotor blades (and at least three blades) can be considered to be similar to a disc when calculating the dynamic properties of the machine. • A rotor with an even number of blades will give stability problems for a machine with a stiff structure. The reason is that at the very moment when the uppermost blade bends backwards, because it gets the maximum power from the wind, the lowermost blade passes into the wind shade in front of the tower.
- 10. Advantages • • The wind blows day and night, which allows windmills to produce electricity throughout the day. (Faster during the day) • Wind power is available in ample amounts in all coastal areas. • The decreasing cost of wind power and the growing interest in renewable energy sources should ensure that wind power will become a viable energy source worldwide. • It does not produce any carbon dioxide.
- 11. Disadvantages • Noise • Capital cost of installing a wind turbine is very high. • Land acquisition problems.
- 12. THANK YOU…