Hello everyone, this is my first article in Youngsday.com and, this is mainly related with renewable energy and wind turbines.
As all you know, energy in the universe is infinite. But we can use only small portion of it. Besides, we use energy mostly coming from fossil fuels. There are two outcomes due to this type of energy usage. First, fossil fuels are not infinite; it will vanish from the Earth eventually. When we say fossil resources are not infinite, some people propose the Nuclear energy. However, this type of energy is worse than fossil resources. We cannot underestimate the energy outcome emerging from nuclear fusion. Yet, it is too risky. Second, pollution is inevitable outcome of fossil fuel usage. We cannot live without energy, but we make the life worse on the planet Earth by using the fossil energy. There are lots of studies made by scientists. All of them come out with the same result, “we should stop using fossils as energy sources. Otherwise, there won’t be a planet to live in it. So, there is only one way to go with, it is RENEWABLE ENERGY.
There are plenty of renewable energy sources such as wind, sunlight, tides, waves, geothermal etc. Today I will discuss the wind energy, we will answer the questions like Why wind energy? What is wind turbine? How do we obtain energy from wind turbine? How do we construct a wind turbine? Why should we use it?
First of all, why we need to use wind as energy resources is that we can obtain it freely; it exists in every part of the world. Furthermore, construction cost is not that cheap it has a very low operational cost.
Secondly, we use wind turbines to obtain the energy coming from wind. They basically, convert kinetic energy of air into mechanical energy. And, we use this mechanical energy as electricity in our houses.
The main idea of using wind turbine is to transfer the wind energy to the blades of the wind turbine. And then, these blades initiate the turbine inside of the hub that is the center point of the blades. And, this turbine will convert this wind energy into electricity.
In the design part of the wind turbine, we mainly consider two things, stiffness and strength checks. For the wind turbine producing 5MW power, the tower height nearly 90m, and the radius of the blades are 130m. So, loads produced by winds become great amount due to these dimensions.
Stiffness is important due to the natural frequency of the support structure.Natural frequency of the structure must be between excitation frequencies of:
- Blade mass imbalance (1P): Weight of the blades are different, this causes shifts in center of gravity and causes eccentricity and side to side vibrations.
- Tower Shadow (Blade passing) (3P): As the blades rotate, tower is shielded by a blade in each time the blade passes in front of the tower, it causes back and forth vibration .
It is three times greater than the blade mass imbalance, since there are three blades.
1-Combined axial compression and bending condition
2-Shear requirement condition
I don’t want to go in deep but, there is a program called FAST to generate the loads that is applied by wind to the blades of the turbine. Then, we use these loads to check the stiffness and strength requirements. There is also a structural analysis program called SAP2000. It can calculate the moments, axial loads and shear forces, and natural frequency of the structure.
I want to end my essay with some facts. There are now over two hundred thousand wind turbines operating worldwide, with a total nameplate capacity of 282,482 MW as of end 2012. The European Union alone passed some 100,000 MW nameplate capacities in September 2012, while the United States surpassed 50,000 MW in August 2012 and China passed 50,000 MW the same month.
With respect to total investment cost, The total cost per installed kW of wind power capacity differs significantly between countries. The cost per kW typically varies from approximately 900 €/kW to 1,150 €/kW.
For the 5MW wind turbine, total cost is Foundation = 50.000 €, Tower = 300.000 €, Rotor = 160.000 €, Generator = 340.000 €,
IN TOTAL = 800.000 €
As I said before, construction is a little bit expensive for generating wind energy. However, we can produce 15 million kWh per year. And, statistics shows that a household consumes 9000 kWh per year. As a result, we can meet the electricity need of 1650 household in a year with a 5 MW wind turbine without emitting any hazardous gases to the atmosphere.
We did not understand the importance of renewable energy yet. However, when the day that there won’t be any fossil fuel comes, every single person will meet their electricity need with renewable energy sources. And one of the most significant sources will be wind energy.