The cool April breeze softly brushes against your hair and blows away your cap on your way home. Massive hurricanes ambush the tropical coastlines and devastate cities and towns. These two scenes look totally different, and yet in reality demonstrate the two-sidedness of the same phenomenon - wind. Indeed, wind can be so refreshing and soothing, but can also be arguably the deadliest thing on Earth. All these are the result of a very simple phenomenon – air moving from one place of the Earth to another as a consequence of temperature difference.

As a rule, in some areas of the Earth air is heated more than in other areas (generally air above oceans are heated more). Hot air is less dense than cold air, and it rises above cold air slides in to fill the empty space. This flow of air is what we call 'wind.' Depending on various factors such as humidity and air density, as well as how big the temperature difference is between the hot and the cold, the wind speed can vary greatly.

Recall in the very first episode that anything that moves has kinetic energy. The moving air particles in the drafts of wind often conveys enormous amounts of kinetic energy from one place to another (if the energy is too enormous, the air particles can uproot trees and topple houses, and that is called a typhoon). This kinetic energy can be harnessed to do work for us in a variety of different ways.

The History of the Human Use of Wind

Though wind power is predominantly used for production of electricity nowadays, it has been an extremely useful source of energy for humans since long before the introduction of electric generators. Of all human usage of wind in their lives, the windmill has been the most conspicuous. First used in Persia around 400 BCE, it has seen (and still sees) wide usage all over the world. The windmill converts the wind's kinetic energy into a rotational turning moment by means of a turbine, the wings of which spin as wind passes by. This rotation was used to grind crops or pump water, greatly increasing agricultural efficiency and yield in the Netherlands, the windmill was used to pump water from dammed-off saltwater areas and create arable land.

Another usage of wind by humans is probably the sail. Before the invention of coal-fed steam engines, ships had to rely on the sea currents and manpower (by means of oars) for speed and maneuver. The sail is a large piece of textile that receives the kinetic force of air current and push the ship forward, in the direction of the wind. Though the wind had its problems (it could not be used, for example, during a storm in which the wind is too powerful and just rips the sail to pieces), it saved loads of manpower compared to inducing the speed from sheer manpower and oars, and was a crucial element of seafaring for at least four millennium.

How Does Wind Produce Electricity?

Recall that electric generators generate electricity by means of a rotational moment. The Wind Turbine uses multiple wings connected to a central axle to catch the wind, in a way very much similar to the way windmills run. The axle is connected to the generator when wind blows, the wings receive the wind and the axle rotates, and the generator generates electricity. Rather than having a single enormous giant turbine, it is much more efficient to build several smaller wind turbines over a larger area. This makes individual turbines far smaller than power plants using other sources of energy, which take up whole buildings (and sometimes more).

 

Advantages & Disadvantages

The best part about using wind power to generate electricity is probably 'the clean side of it.' Wind Power is a completely renewable energy source - as long as the Earth orbits around the sun, there will be wind blowing about on the surface of the Earth, and there will always be wind. Besides, using wind involves no emission of any sort, either chemically or thermally. Wind turbines are generally cheaper to build, and require far less personnel to maintain compared to power stations they do not take up enormous amounts of space, and hence their presence has no great impact on the environment.

If you think wind power is perfect, there are the downsides as well. Wind turbines can obviously be only installed in areas with frequent and sufficient wind (a minimum of wind speed 3 m/s is required to drive a wind turbine) - little other areas than hilltops or coastlines are eligible for this requirement. Unfortunately, the greater part of such places is already occupied by other infrastructures that are usually as much indispensable to our lives as energy, such as factories or beaches. Even when this is not the case, the local inhabitant often complain of wind farms being eyesores (I guess they can be for some people), and their rights must be appreciated as well.

The energy produced itself is a problem as well. Compared to what is invested, wind turbines do not yield a very rewarding output, for wind is quite unpredictable and wind turbines cannot move once they are installed. Because of the low energy output, no country employs wind as the main source of energy rather, wind is used predominantly by individuals who live in a remote area where it is inadequate to connect to a power station (e.g. in an island). Along with solar power, wind power is the most feasible energy option for such individuals who prefer self-sufficiency of energy.

Case Study

For governments in our times, wind power is usually an auxiliary source of energy (the output just isn?t substantial enough). However, because it is cost-effective, renewability, and has minimum impact on the environment, remote areas distant from power plants are usually supplied with energy produced from local wind turbines. This is particularly an ideal strategy for countries that have a large land mass but low population density (Russia and Canada), or has the majority of her population concentrated in certain regions (China). The US, Germany and Spain currently lead the world in terms of total installed wind power capacity.

Rank	Country	Installed Capacity (MW)	% of National Electricity Demand
1	USA	25,369	1.9
2	Germany	23,902	6.5
3	Spain	16,740	11.7

China has recently invested thoroughly in her wind power industry, and currently has the fourth largest installed wind power capacity. Most of the wind-produced energy, however, is for provinces in remote, western part of China the major cities on the east coastlines (where most of the population is concentrated) still runs on other forms of conventional energy, such as fossil fuels.

While wind power may seem a tempting energy source for LEDCs (Less Economically Developed Countries), wind power is rather infeasible for the greater part of these nations. The majority of the world?s LEDCs are located near the Equator these areas are very hot and humid, and wind is very rare even on the coastlines and high altitudes – let alone substantial wind to power wind turbines.

Areas of Research in the Future

I suppose further research may result in better efficiency of wind turbines, but this extra energy will not be big enough to make any distinguishable difference. What is under research currently is an oceanic wind-farm platform, which can move around the sea searching for areas with sufficient wind (or would you rather build wind turbines on a giant truck and drive it around the world?). The drawback is that there is yet no method of storing the vast quantity of electricity produced. with current technology no battery has a capacity large enough to store such energy (obviously connecting a ship to your house with thousands of kilometres of wire is out of the question). Also, in my opinion, energy will have to be spent on getting this ship moving, and we should consider if the energy produced minus the energy spent on the moving the ship will be really worth the investment. On the long run, wind will never be the ultimate solution to all our energy problems, but at least people can individually purchase wind turbines to produce some energy and take a little load off power plants.

Citation of Images:

Turpin, Fred. Wind Blowing Across Fields of the Heart. Digital image. Wind Blowing Across Fields of the Heart. Fred Turpin's Poetry Blog, 29 Feb. 2012. Web. 21 July 2014. <http://fredturpin.wordpress.com/2012/02/29/wind-blowing-across-fields-of-the-heart/>.

How wind is formed. Digital image. Wind Energy. HK Electric, 10 Jan. 2014. Web. 21 July 2014. <http://www.hkelectric.com/web/AboutUs/RenewableEnergy/ExhibitionCentre/WindEnergy_en.htm>.

Schematic diagram of a wind turbine. Digital image. Wind Energy. HK Electric, 10 Jan. 2014. Web. 21 July 2014. <http://www.hkelectric.com/web/AboutUs/RenewableEnergy/ExhibitionCentre/WindEnergy_en.htm>.

Wattle Point Wind Farm, next to the coast of Edithburgh in South Australia, commissioned in 2005 with an installed capacity of 91 MW. Digital image.Wind Energy. HK Electric, 10 Jan. 2014. Web. 21 July 2014. <http://www.hkelectric.com/web/AboutUs/RenewableEnergy/ExhibitionCentre/WindEnergy_en.htm>.

Wind Energy Through the Years. Digital image. Wind Energy. HK Electric, 10 Jan. 2014. Web. 21 July 2014. <http://www.hkelectric.com/web/AboutUs/RenewableEnergy/ExhibitionCentre/WindEnergy_en.htm>.