Wind can be used to power wind turbines which, by using electrical generators, creates electrical power. Wind power is a so-called ”intermittent energy source”, since the wind can not be controlled and can be difficult to predict.
In the year 2019, the installed wind power capacity exceeded 651 GW globally and wind supplied 1430 TWh of electricity; approximately 5.3% of the total worldwide electrical generation.
What are wind farms?
A wind farm is a group of wind turbines in the same location used to produce electricity. Alternative terms are wind park, wind power station and wind power plant. Wind farms exist both onshore and offshore and vary greatly in size – from just a few turbines to several thousand. The famous Gansu Wind Farm in China is projected to house 7,000 wind turbines when finished. China, India and the United States are all home to very large onshore wind farms.
Two examples of factors that are important to take into consideration when selecting a location for a wind farm are wind conditions and what would be required to transmit the electricity from this spot. Some places that are ideal from a wind perspective would require huge investments in electrical transmission infrastructure if a wind farm would be placed there.
When it comes to wind conditions, mountain passes are often highly suitable for onshore wind farms, since they work as wind tunnels, channelling air from one side of the mountain range to the other.
Wind speed will impact the rate of electricity generation. The faster the wind, the more electricity is produced. However, strong winds – especially if there are gusts and turbulence – require stronger turbines and those are more costly. The perfect conditions for a wind farm are strong and consistent winds, with as little turbulence as possible. Ideally, that consistent wind should also be coming from a single direction year-round. Of course, in reality, wind farms must be built to handle gusts, turbulence and winds from various directions, but some locations are more problematic than others when it comes to these aspects and are typically avoided even if they are appealing due to their strong winds.
The wind blows faster at some distance from the ground, due to a reduced influence of drag. At and very near ground level, the wind is hampered by topography, trees, surface roughness, etcetera. Move up a bit from the ground, and there is typically less to block the wind. It should be noted, however, that if you were to move your wind turbine to an altitude of hundreds of meters above sea level, you would find that the power of the wind is actually less up there. That is because the power in the wind decreases proportionally to the decrease in air density.
As mentioned above, wind power is an intermittent energy source, since the wind is not constant in a particular location. If we look at the wind power output for a certain location from year to year, it tends to be quite similar. If we instead look on a day-to-day or even hour-to-hour basis, we will notice sharp variations. Because of this, wind generated electricity is typically used in conjuction with other power sources, to make sure that enough electricity is available 24/7.
Here are a few examples of power management techniques:
- Have one or more alternative power sources available that can be despatched as needed, such as generators that run on petrol.
- Use wind power in conjunction with hydroelectric power
- Have geographically distributed wind turbines in locations selected to complement each other
- Grid storage
- Selling excess electricy on high-yield days, and use the money to purchase electricity on low-yield days
- Reduce electricity usage when on low-yield days