Wind Energy
The winds of the Earth are caused by the Sun’s heating. The temperature difference between regions causes winds. The Sun’s 2 percent energy is converted to the winds, corresponding to 30 million TW. The world power consumption is 25343 TW. The total wind energy corresponds to 1100 times the world power consumption in 2021.
Sounds awesome, we can fix the energy problem. No, we cannot, right now. There are obstacles to wind energy, and in this article, I will going to introduce them and their solutions.
The wind energy of the USA could produce more than 16 billion GJ of electricity. It is one and one-half times the electricity consumed in the USA in 2000 [2]. As of 2021, the total wind energy capacity of the United States is approximately 118.3 gigawatts (GW) according to the American Wind Energy Association (AWEA).
Wind energy is calculated with the same units of solar energy. Watts per square meter. However, one must be wary that solar energy is the surface area of the Earth’s surface, in wind energy, is a vertical square meter perpendicular to the wind flow [2]. Wind energy is used by wind turbines to produce electricity. There are types of wind turbine types [2];
· Wind-driven generators
· Wind generators
· Wind turbines
· Wind-turbine generators
· Wind energy conversion systems
Wind turbines are classified according to their axis as horizontal-axis wind turbines (HAWT) and vertical-axis wind turbines (VAWT). HAWTs work by getting wind perpendicular to their blades while turning blades in the horizontal direction. VAWTs get wind and deliver motion to the generator in a vertical fashion.
Energy calculations of a wind turbine
Kinetic Energy of a Moving Body= 1/2 . m . V²
Power of Air = 1/2 . (Mass flow rate of Air) . V²
Mass flow rate of Air = Density of Air . V . A
Power of Air = 1/2 . (Density of Air . V . A) . V² = 1/2 . (Density of Air . A) . V³
Where A is surface area, and V is speed. As we can see from the formula wind energy is proportional to speed’s cube. From the equation, we can also see that it is proportional to the surface area. Surface area is equal to;
Surface Area= (Pi / 4) . D²
Power= k (constant) * S (surface area) * V³ (speed)
The constant (Betz Limit) for wind turbines is 0.59, meaning that 59.3% of wind energy can be converted to electrical energy. Betz limit comes from the 16/27 which is roughly equal to 0.59. This is the ratio of the power extracted by the wind turbine to the power available in the wind. The Betz limit is the theoretical maximum efficiency that can be achieved by a wind turbine in converting the kinetic energy of the wind into mechanical energy. The limit is based on the assumption that the wind passing through the turbine is slowed down to two-thirds of its original velocity, which is the maximum amount of kinetic energy that can be extracted from the wind without slowing it down to zero velocity.
Each wind turbine installed can avoid 3633 metric tons of CO2 emissions [2].
The power coefficient expressed as;
Cp= 4R (1-R)²
Where R is wind speed ratio. According to this formula, coefficient can take maximum number of 0.59.
Additionally, wind turbines cannot function above 55 mph [2].
The first wind turbine programs started in America in 1975. However, there were wind turbines in Soviet Russia in Balaklava (Crimea) as early as 1931. European countries also had small-scale wind turbines. An important project came from America with the creation of MOD-0, a wind turbine with 38 meters of blades. This was followed by MOD-1, MOD-2, and so on.
Based on data from the International Energy Agency’s 2020 report, here are the global shares of primary energy supply by source for 2019 [3]:
- Oil: 33.1%
- Coal: 26.9%
- Natural gas: 23.8%
- Renewables: 11.2% (including hydro, wind, solar, geothermal, and bioenergy)
- Nuclear: 4.9%
The renewable share on the energy types is only %11.2. It was %10.4 on 2018. It is increasing but not with enough speed. In the table below, you can see the renewable energy usage increase by the years. Also, it is notable that coal energy is the only energy type that is decreased within years. Thus, there is a transition from coal to renewables.
Wind energy gives us an alternative for global warming solutions. As you can see above, its formulas are determined and usage very much understood. Decreasing the prices, increasing the efficiency would be the best way for increasing demand. I am sure the wind energy will be a helper along with solar energy.
References
[1] “World electricity consumption 2021 | Statista.” https://www.statista.com/statistics/280704/world-power-consumption/ (accessed Mar. 26, 2023).
[2] F. ’Spellman, The Science of Renewable Energy, 2nd ed. CRC Press, 2016.
[3] Key World Energy Statistics 2020 — Analysis — IEA. (n.d.). Retrieved April 7, 2023, from https://www.iea.org/reports/key-world-energy-statistics-2020
