About wind power
Wind is moving air
As the Earth turns, the sun heats up some parts of the land and sea more than others. The air above the heated parts is warmed, becomes lighter than the surrounding air and starts to rise. In other areas cool air sinks because it is heavier than the surrounding air. The air pushed out by the sinking cold air is drawn under the rising, warm air, creating winds.
Wind will blow wherever there is a difference in air pressure – always from high to low pressure areas. Wind always starts the same way whether gentle or hurricane force.
How wind makes energy
Wind has been used for thousands of years to move ships, pump water and drive machinery. Wind turbines are designed to turn the kinetic (moving) energy of the wind into electrical energy.
Energy is generated in basically the same way as hydropower. Wind spins the turbines blades which in turn spin a magnet inside a coil of conductor (called a generator). Although the basics of generating power are similar to hydropower, there are some important differences.
- Wind speed varies. To cope with variable wind speed each wind turbine has a gearbox, brakes and an anemometer. The anemometer measures wind direction and speed - the gearbox adjusts the speed of axle which ensures the generator is working efficiently. If the wind is too strong the brakes stop the blades from turning.
- Direction changes. When generating energy from water, it is directed down pipes to a turbine. For wind power, the turbine moves to the wind. The nacelle is the ‘box’ on top of tower; it contains all the important equipment and holds the blades in place. To capture energy from the wind the whole nacelle turns to face the direction of the wind. It can turn 360 degrees and turn around three times.
- Size of generators. In hydropower stations there are generally fewer and larger turbines, in comparison wind turbines are smaller. For example, Hydro Tasmania’s turbines at the Gordon Power Station are 150 MW and there are three of them, at Bluff Point Wind Farm the turbines are 1.75 MW and there are 37 of them.
What makes wind power renewable?
Wind is generated from the heat of the sun, therefore it is not ‘used up’ after it has blown past a turbine, it continues to blow around the world. It is renewable because it can be used again and again.
Tasmania has a world-class wind energy resource – the island lies directly in the path of the roaring 40s, the prevailing westerly winds that circle the Earth’s high southern latitudes.
When these winds reach the west coast of Tasmania, they have blown across the cooling Southern Ocean for thousands of kms since last touching warm land on the tip of South America.