The increased interest in renewable energy has lead to an increased demand for more wind energy. Globally, wind energy has a capacity of 743GW and produces over 5% of global electricity.
However, wind power production and electricity output are highly dependent on many factors including, wind speed, wind direction, etc.
The amount of electricity a wind turbine produces depends on its rated power capacity and reliable winds. In other words, they need consistent winds at the right wind speed to create the amount of energy that they’re built to generate.
So what is that in watts? How much energy does a wind turbine actually produce? This article takes a more in-depth look at wind energy productions and energy outputs.
What Is a Wind Turbine?
Turbines are rotary devices that convert a fluid flow into labour, energy, or other valuable work. For example, old windmills used the wind to grind grains or pump water.
Therefore, a wind turbine converts wind into electricity. According to the US Energy Information Administration (IEA), there are two basic types of wind turbines: vertical-axis wind turbine (VAWT) and horizontal-axis wind turbine (HAWT).
The two turbines operate similarly; however, the three-rotor horizontal-axis turbines are the most common because of their higher efficiency and maximum power output.
How Does a Wind Turbine Work?
A wind turbine produces power by turning kinetic energy into rotational energy that will then produce electricity. For example, with a horizontal-axis wind turbine, its aeroplane-like blades catch the wind and spin.
The rotation of the rotor blades turns the gearbox of the generator within the nacelle and creates electricity. More specifically, the blades connect to a shaft that spins at around 30-60 rotations a minute, depending on the model.
That shaft then connects to a gearbox that increases those rotations by 30-100 folds, reaching a rotational speed that generates electricity. The bigger the rotor blades of the wind turbine, the greater the rotational torque and the power generated.
Most turbines then convert the current from alternating current (AC) to direct current (DC) and back again. It does this to match the frequency and phase of the electric grid that it is connected to.
It’s important to note that wind turbines have a cut-in and a cut-out wind speed. Some wind turbines only start generating energy at around 5 miles per hour, while most large-scale wind turbines require a cut-in wind speed of at least 7 miles per hour.
Some models have a higher cut-out wind speed, but most wind turbines stop working at speeds greater than 56 miles per hour. This is to protect the rotor blades from damage at high wind speeds.
Lastly, most wind turbines today have sensors that change and control the blades’ orientations and direction to gather the most wind for maximum energy production.
How to Measure Wind Energy?
Often, manufacturers measure the capacity of their wind turbines and give the wind turbines a power rating, which will be in front of the model name. These power ratings are measured in kilowatts (kW) and megawatts (MW).
Electricity generation and consumption are usually measured over a period of time. Therefore, the energy consumed is measured in kilowatt-hours (kWh) and megawatt-hours (MWh)
Most residential turbines are rated around 2-10kW; whereas, commercial wind farm turbines are rated at 1MW up to 14MW.
However, these power ratings are the output of wind turbines at an optimal wind speed, which is not the case in real life. This is because a wind’s speed changes and varies throughout the day and year.
In fact, wind speed and energy production are not proportional. This means when wind speeds drop; the power production decreases significantly more. For example, if the wind speed decreases by half, electricity production drops by eightfold.
That’s why companies measure the capacity of wind turbines. It’s usually a percentage that measures the actual output over the potential output.
Generally, Wind turbines can run anywhere from 15-50% of their rated capacity, with a modern wind turbine averaging around 30-40%. Therefore a 1MW wind turbine might only produce 15kW or 50kW.
Annually, that could add up to a difference of 4,380MWh, which is enough energy to power about 400 average energy-consuming households in the US.
Although winds vary day by day, this percentage is an excellent way to estimate the amount of electricity a turbine will produce.
How Much Energy Does a Wind Turbine Produce?
So how much power does a wind turbine produce? The power wind turbines produce significantly depends on the model, size, and wind conditions. There are many factors to consider, which we will discuss later in the article, but below are the average energy outputs by different sizes of HAWTs.
Commercial Wind Turbines
Commercial generally means large turbines. On average, onshore 2.5-3MW wind turbines produce about 6000 MWh annually. On the other hand, a 3MW offshore turbine may produce twice that amount.
Onshore and offshore wind turbines vary due to the amount of wind they receive. Additionally, The size of the turbines also dramatically affects the amount of energy produced.
The largest wind turbine to date is the Haliade-X 14MW turbine produced by General Electric. This offshore turbine can generate up to 74GWh of wind power per annum.
Residential Wind Turbines
On the other hand, there are small residential wind turbines that you can install on roofs. However, these turbines have a much lower capacity due to their size, with most residential wind turbines ranging from 1kW to 10kW.
Depending on geography, height, and placement of turbines, a small 2kW wind turbine can generate up to 3,000kWh while a 5kW turbine can generate three times that amount.
These smaller turbines are suitable for most small residential homes as domestic turbines of more than 10kW tend to be larger. However, this means it’ll be harder to place on the roof of a smaller house.
Portable Wind Turbines
These are foldable turbines that range from 10W to 2000W with varying sizes as well. These portable wind turbines produce low energy output and exist mainly for campers and RV owners. This low wind turbine output is mainly suitable for charging phones, cameras, or small appliances.
Different Types of Wind Turbines
This article has mainly focused on the standard three-rotor horizontal-axis wind turbine because it’s the most efficient turbine to date. However, what are some alternative wind turbines out there? And how much power does each wind turbine generate?
There are various types of vertical-axis wind turbines. They’re capable of picking upwind from any direction; however, this also makes them less efficient than their horizontal-axis counterpart.
More recently, these vertical-axis turbines have been redesigned to be more efficient and handle higher wind speeds.
The Icelandic company, Icewind, has invented one that’s only 1.5m in height and can handle up to 138mph winds. However, it’s only rated at 600 watts.
This wind turbine is a contained portable turbine that can be placed in cities. The design allows it to collect wind from any direction while also being safe for people and animals.
Unlike the vertical-axis turbines, the blades’ design of the Powerpod makes it more efficient than other alternative turbines. For example, a 1kWh Powerpod turbine can produce 3 times more power than a similar-sized horizontal-axis turbine.
Although not turbines, there are bladeless wind energy harnessers and converters such as the vortex-induced vibration resonant wind generator, the electrostatic wind energy convertor (EWICON), or the Solar Wind Energy Tower (SWET).
These devices are similar in that they still use wind’s kinetic energy and convert it into another type of energy.
Factors Affecting Wind Energy
As mentioned previously, wind turbines do not continuously operate at total capacity. Therefore, it’s essential to consider these main factors that affect wind energy production.
Although this factor seems too obvious, it’s important to note a few things. First, most might agree that wind has an advantage over solar in that it can potentially be 24/7.
However, in reality, there will be some days or weeks out of the year where there is not enough wind passing through. Moreover, the wind could also be affected by temperatures and barriers that might block it.
As mentioned previously, wind turbines need a cut-in speed to start turning. The wind has to be strong enough for the wind turbine to start producing electricity. A gentle breeze cannot power, let alone start a wind turbine.
Therefore, the wind speed cannot be lower than 5mph depending on the model of the wind turbines. A larger wind turbine might require a higher cut-in speed of 7mph.
On the other hand, if the wind speed exceeds a certain amount, it can cause potential damage to turbine blades. Most turbines can handle up to 56 mph wind speeds, although newer designs and vertical-axis models can handle more.
Lastly, the wind speed needs to be constant to create a consistent amount of energy. Wind changes constantly, and the fluctuating wind speeds decrease efficiency and output.
Again, everything depends on the wind, which varies depending on location and geography. Differences in temperature cause warm and cool air to rise and sink, causing different atmospheric pressures, and therefore wind.
For example, offshore turbines get more consistent and stronger winds than the average onshore wind turbine. Winds blow faster and steadier over the ocean because no barriers such as mountains or trees cause friction.
This discovery has lead many countries to increase offshore wind farms.
Moreover, wind maps help determine a good location, but local structures like trees or buildings can also disrupt airflow, causing turbulence.
To avoid turbulent winds, which cause wind turbines to be less efficient, the lowest part of the turbine’s blade has to be at least twice the structure’s height.
Wind speed and power increased with altitude and height. The higher the placement of the turbine or the taller the height of it, the more outstanding production of energy.
For example, a 30-meter wind turbine can generate about 30% more energy than a 15-meter wind turbine. This percentage can increase or decrease depending on surrounding structures as well.
In fact, there are various airborne wind power projects in development looking to harness wind power thousands of meters in the sky.
Although not as important as wind speed, the size of the blades can affect the amount of energy produced. Larger rotor blades allow for greater rotational torque and will generate more energy than smaller ones.
Wind turbines are getting larger and more prominent in height and size. For example, the present largest wind turbine, the Haliade X, has 107 meter long blades.
Unlike the power rating, the capacity factor measures how effectively a turbine captures wind and how much electricity it converts it into.
The capacity factor is usually expressed in a percentage and is determined using a wind turbine’s potential and realistic capacity output. Manufacturers usually determine this factor by measuring the wind turbine output over a year.
Turbines can’t convert 100 per cent of the wind passing into electricity. In fact, Betz’s laws limit the efficiency to a theoretical 59.6% because the wind would still need the energy to blow past the rotors and turn them.
Due to friction and other mechanical errors, modern wind turbines generally have an average capacity factor of around 35-45 per cent. As a result, the maximum efficiency rating ever reached is 50 per cent.
Wind Energy Production in Other Countries
With improvements in technology, wind power plays a significant role in renewable energy consumption.
In fact, the European Wind Energy Association (EWEA) and the European Commission believe that wind energy could supply up to 50 per cent of the EU’s energy consumption by 2050. Denmark already covers 47% of its energy demands using wind power.
Scotland set a record in wind power output during the first half of 2019, producing enough to power every home in the country and then some.
According to the American Wind Energy Association (AWEA), US wind energy currently supplies 25 per cent of the nation’s electricity consumption. The government projects that wind energy production will increase by over 300 per cent by 2050.
On the other side of the globe, China has nearly tripled the wind power capacity installed in 2020, giving the country the largest global wind power capacity. India also boasts fourth in wind capacity, being the fourth largest in the world.
In Latin America, wind energy production plays a much smaller role; however, wind capacity has increased in countries like Brazil, Chile, and Uruguay.
The electricity produced by wind turbines reveals the feats of human engineering. It also gives us hope for a complete shift towards clean energy.
GE claims that a single rotation of the Haliade X turbine could power a single UK house for more than two days. That’s an estimated 20kWh or more in a single turn of its rotors.
With improvements in wind technology, energy production could be enough to power many homes throughout the world. However, despite the potential, average daily production could vary dependent on the wind.
However, with the increase in wind farms both onshore and offshore, energy consumption is shifting towards more clean energy such as wind.
Wind power has the advantage of not costing as much in maintenance or power production. The low cost makes it one of the cheapest forms of renewable energy sources available.
Contrastly, wind energy production also comes with its disadvantages. Wind farms take up greater space, needing multiple acres of land to produce hundreds of megawatts of energy.
Also, despite producing power every hour of the day, the wind does not blow every hour. The many factors that affect wind turbines mean they cannot always run at their full capacity.
How much energy is produced by a wind turbine depends on too many factors such as wind speed, location, efficiency, height, and size? Moreover, the model and design of wind turbines affect their capacity and output as well.
Despite all this, wind power is a good clean energy alternative to fossil fuels. As the wind industry expands, more electric energy consumption will shift towards this renewable energy.