Mini Project
Introduction of Renewable Energy
CPB40003
Hello everyone! We are
student of Malaysian Institute of Chemical & Bioengineering Technology
(UniKL Micet). Our group consist of 3 members which is Ikram Hakimi, Ahmad
Tawfiq and Nik Nur Afiqah. So, this semester mini project for subject
introduction of renewable energy is to create a blog and conduct an interview
for renewable energy that our group has choose which is Wind Energy. Wind
energy now days mostly use in western country. The purpose of this blog is to
get some knowledge about what is wind energy, what type of wind turbine and the
working principle of this type of renewable energy.
What is wind energy?
Wind turbines, like windmills, are mounted on a tower to capture the most energy. At 100 feet (30 meters) or more above ground, they can take advantage of the faster and less turbulent wind. Turbines catch the wind's energy with their propeller-like blades. Usually, two or three blades are mounted on a shaft to form a rotor.
A blade acts much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on the downwind side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is actually much stronger than the wind's force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller, and the turning shaft spins a generator to make electricity.
Wind turbines can be used as stand-alone applications, or they can be connected to a utility power grid or even combined with a photovoltaic (solar cell) system. For utility-scale sources of wind energy, a large number of wind turbines are usually built close together to form a wind plant. Several electricity providers today use wind plants to supply power to their customers.
Stand-alone wind turbines are typically used for water pumping or communications. However, homeowners, farmers, and ranchers in windy areas can also use wind turbines as a way to cut their electric bills.
Small wind systems also have potential as distributed energy resources. Distributed energy resources refer to a variety of small, modular power-generating technologies that can be combined to improve the operation of the electricity delivery system.
Types of wind turbine
There are two types of wind turbines :
Horizontal Axis Wind Turbines (HAWT)
Horizontal axis wind
turbines have the main rotor shaft and electrical generator at the top of a
tower, and they must be pointed into the wind. Small turbines are pointed by a
simple wind vane placed square with the rotor (blades), while large turbines generally
use a wind sensor coupled with a servo motor to turn the turbine into the wind.
Most large wind turbines have a gearbox, which turns the slow rotation of the
rotor into a faster rotation that is more suitable to drive an electrical
generator.
Vertical Axis Wind Turbines
Verticalaxis wind turbines, as shortened to VAWTs, have the main
rotor shaft arranged vertically. The main advantage of this arrangement
is that the wind turbine does not need to be pointed into the wind. This is an
advantage on sites where the wind direction is highly variable or has turbulent
winds.
With a vertical axis, the generator and
other primary components can be placed near the ground, so the tower does not
need to support it, also makes maintenance easier. The main drawback of a VAWT
generally create drag when rotating into the wind.
Windmill Design
- A windmill capture wind energy and use a generator to convert it into electrical energy.
- The design of a windmill will define how efficient of the energy.
- It must determine the size of turbine and generator.
How wind turbine works?
Function of each parts in wind turbine:
Anemometer:
Measures the wind speed and transmits wind speed data to the controller.
Blades:
Lifts and rotates when wind is blown over them, causing the rotor to spin. Most turbines have either two or three blades.
Brake:
Stops the rotor mechanically, electrically, or hydraulically, in emergencies.
Controller:
Starts up the machine at wind speeds of about 8 to 16 miles per hour (mph) and shuts off the machine at about 55 mph. Turbines do not operate at wind speeds above about 55 mph because they may be damaged by the high winds.
Gear box:
Connects the low-speed shaft to the high-speed shaft and increases the rotational speeds from about 30-60 rotations per minute (rpm), to about 1,000-1,800 rpm; this is the rotational speed required by most generators to produce electricity. The gear box is a costly (and heavy) part of the wind turbine and engineers are exploring "direct-drive" generators that operate at lower rotational speeds and don't need gear boxes.
Generator:
Produces 60-cycle AC electricity; it is usually an off-the-shelf induction generator.
High-speed shaft:
Drives the generator.
Low-speed shaft:
Turns the low-speed shaft at about 30-60 rpm.
Nacelle:
Sits atop the tower and contains the gear box, low- and high-speed shafts, generator, controller, and brake. Some nacelles are large enough for a helicopter to land on.
Pitch:
Turns (or pitches) blades out of the wind to control the rotor speed, and to keep the rotor from turning in winds that are too high or too low to produce electricity.
Rotor:
Blades and hub together form the rotor.
Tower:
Made from tubular steel (shown here), concrete, or steel lattice. Supports the structure of the turbine. Because wind speed increases with height, taller towers enable turbines to capture more energy and generate more electricity.
Wind direction:
Determines the design of the turbine. Upwind turbines—like the one shown here—face into the wind while downwind turbines face away.
Wind vane:
Measures wind direction and communicates with the yaw drive to orient the turbine properly with respect to the wind.
Yaw drive:
Orients upwind turbines to keep them facing the wind when the direction changes. Downwind turbines don't require a yaw drive because the wind manually blows the rotor away from it.
Yaw motor:
Powers the yaw drive.
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