This is one of those questions that just come right at you. But considering the events happening at this time, this is an apt question. Renewable energy adoption is at the highest and wind is one of the prominent sources of electrical energy. To answer this question in a way that you’ll enjoy, permit us to take you through some basics of electrical energy generation via wind energy.
Wind; The Resource
When it comes to electrical energy generation, the attribute of the wind that we exploit is the speed. This is simply the speed at which air particles move from the region of high pressure (where there is cold air) to the region of low pressure (where there is warm air).
This is why wind energy is best utilized in areas where the air pressure is high as this guarantees a higher speed and much more consistency.
Exploiting the Resource with a Turbine
A wind turbine is simply a machine that is able to exploit the kinetic energy of the wind and turn it into mechanical or electrical energy. Ideally, the turbine consists of components such as the tower (for elevation), the rotor and the nacelle (box), and most importantly, the foundation (to avoid falling).
Going deeper, we realize that the nacelle consists of the gearbox, a transformer, a generator, and a control mechanism. We also see that the hub holds the blades of the rotor in position to ensure that they do not fall off when they turn.
The length of the rotor blades has an effect on the output you get from a wind turbine and this relationship is demonstrated in the ensuing paragraphs. But usually, the length of a modern, commercial turbine exceeds 60 meters for commercial wind turbines with a diameter of 120 meters (longer than a football field). They usually have three rotor blades. This sort of turbine can produce around 6 MW of power and this is enough to power 5000 conventional households.
Wind Turbines and Their Sizes
Let’s have a clearer view of the average size of a wind turbine and how much power it can provide. An average wind turbine today can provide between 2.5 MW and 3 MW. This is enough to power about 1500 average households. In 1985, the average wind turbine couldn’t provide more than 1 MW of power and the diameter was around 15 meters.
Six years ago, in 2012, the average size was a rotor diameter of 100 meters and an output power of 2.5 MW. But the average can be quite misleading. We have several turbines now with an output of 7.5 MW.
Size evolution of wind turbines
The Biggest Wind Turbine in the World
Here’s a disclaimer, with the rate of development, it is possible that another turbine that exceeds this facility is built soon, rendering this post outdated. So, enjoy it while it lasts.
Currently, the world’s most powerful wind turbine emerged from Aberdeen, Scotland and there are 10 more to come around. This is a brainchild of the European Offshore Wind Deployment Centre and is definitely Scotland’s largest offshore wind facility.
It was developed by Vattenfall; a State-owned company in Sweden and the funds for this project was provided by the European Union. The total amount to be spent for this wind farm is about £300 million and it is expected that 70% of Aberdeen’s electricity demand domestically will be met by this farm. It is also expected that the generation capacity will match 23% of the total demand.
Here’s an insight into how it works; if the propeller spins once, an average home can receive enough power for a day. The turbines measure 191 meters in height and this is half the height of the tallest building in Europe. The blade has a diameter of about 164 meters and a blade length of 80 meters. The output is also about 8.4 MW; the best yet.
Calculating the Output Power of a Wind Turbine
We have placed so much emphasis on the size of a wind turbine and some people might be led to believe that output power depends solely on the size. This is wrong.
In fact, the formula for calculating the power of a turbine is given as;
Power (W) = 0.6 x Cp x N x A x V3.
N is the efficiency of the machine being driven
Cp is the rotor efficiency
A is the swept rotor area
And V is the wind speed.
GE just announced their plans to build a turbine with an output of 12 MW. The future really is exciting for wind technology!