Wind Energy as an Alternative Source

Introduction

This universe is composed of Matter and Energy. The genius of the last century, rather than the civilization Albert Einstein showed that the two – matter and energy are two faces of the same coin or two manifestations of the same. Also, that the two can be and are keep interchanging into each – other. However, not wandering into the philosophical aspect of the subject, it is better to restrict the subject in the realm of the day to day life. While matter signifies inertia, a resistance to change and can be likened to death or the dead constituent of the universe; energy on the other hand signifies the force to overcome this inertia and inculcate the drive or actuation or better still life into the matter or the inertial constituent of this universe. Thus energy and matter symbolize life and death respectively in the Universe.

Needless to say how important is life and therefore, energy for this civilization. The creator has provided us with energy in different forms and it is for us to identify and utilize the different forms of energy for the benefit of humanity in a sustainable manner. Different important forms of energy are – Eatables, being produced by green plants by photosynthesis on a continuous basis every day; Trunks of trees, Fossil fuels like coal, petroleum, etc., tidal energy, wind energy, solar energy, nuclear energy, wind energy, etc. to name a few. It is worth mentioning here that the source of all the energy on this planet is the energy radiated by the Sun, which takes different forms on the Earth by different processes.

Different sources of energy were exploited and used by humans in the order of the ease to exploit them. It is, therefore; not surprising that the form of energy easiest to be exploited i.e. sunlight was used by all the living bodies from the very first day. This still continues to be the most used form of energy and maximum utilization of this form of energy is still considered to be one of the most important solutions to the present-day energy crisis. The next important energy resource to be utilized was eatables produced by green plants, which convert and store the solar energy into the food items they synthesize in the form of chemical energy. The wooden trunks in the form of dry wood were used to produce fire and get heat light, protection against wild animals, and most importantly to cook food. Fossil fuels were then used to serve different purposes like producing heat, cooking food, running plants or engines, producing electricity, etc. With time it was realized that fossil fuels are being consumed at a face much faster than they are being synthesized by Nature and this knowledge alarmed humans and began the search of potential alternatives which are either very huge resources or are seemingly perpetual in supply. A huge energy resource is nuclear energy and this has been exploited to great success and has the potential to offer energy security for a couple of centuries. But this is not the everlasting solution. Some seemingly perpetual energy resources are solar energy and wind energy and the latter will be discussed in the subsequent sections in somewhat detail.

History of Wind Energy Utilization

Humans have been using wind energy either knowingly or unknowingly from time immemorial. It is not so easy to realize that drying clothes by hanging the same in the air is another application of wind energy and how many people use this aspect of wind energy is very large, little realizing that they are using wind energy.

Another very prominent and historical use of wind energy is to propel ships and large boats in the sea. What was being done is that cloth used to be tied across the boat and this used to push the boat when the wind was blowing. It is not easy to say how many sailors have been helped by wind energy in past. Wind energy has been used for many other applications like to pull water from the wells for irrigation, for running various mills, etc.

Wind Energy to Electrical Energy:

Electrical energy has been one of the most important discoveries in the history of science. There are different forms of energy like potential energy, kinetic energy, thermal energy or heat, sound, light, electricity, etc. Of these the most important form of energy is electricity. The position of electricity in different forms of energy can be equated with that of cash in different forms of the asset. Like cash can be spent any time and with the kind of ease into other forms of assets one can also spend electricity with the same degree of ease. Modern civilization has its foundations over electricity. It is no wonder, therefore, that humans have tried to convert almost every form of energy into electricity. Fossil fuels are burnt and the resultant heat is utilized to boils water into steam, which in turn rotates a turbine that produces electricity. In the case of a power plant based on a nuclear reactor; the heat produced in a nuclear reactor produces the steam to rotate the turbines. It can be seen that all that is required to produce electricity is a means to rotate a turbine and it is not surprising, therefore, that someone got the idea as to why not run a turbine from wind itself and so realized the concept of modern day wind energy. Yes, in modern age wind energy refers to the system that produces electricity from the wind using turbines. The scale of this electricity production can vary from a small turbine to cater to the electrical needs of a house to a large network of turbines producing and supplying huge amount of electricity to a grid.

This system consists of the following sub-systems:

1. A set of turbine blades (normally three) to convert the linear velocity of the wind into torque or rotational velocity of the air.
2. An enclosure containing a drive and the generator.
3. A tower to support the turbine blades, the drive and the generator at a height as velocity of air is more at higher heights and
4. Other equipments like control, electrical cable and other auxiliary equipments.

The turbines can have either vertical axis design or horizontal axis design. The two configurations are shown in figure 1, below:

The rating of a wind energy turbine depends on the size of the turbine blade. While a 10 m rotor blade has a power rating of approximately 25 kW this value increase to over 1600 kW for a 70 m rotor blade. An isolated small wind turbine can cater to a single house, a mid sized turbine can cater to a place like a school, and a hospital etc and a chain of large turbines produce electricity to either an industry or to be sold to a utility company. Thus, wind energy turbines have great scalability and have capability to serve a single house as well as a large industrial installation. This makes wind energy as a unique energy resource.

Current Status and Potential

The installed capacity of wind energy was approximately 94 GW in 2007 up from approximately 59 GW in 2005 (wikipedia.org) implying an impressive compounded annual growth rate of approximately 26.2%; which is the highest growth rate for any form of energy. The important country with sizeable installed wind power capacity are Germany, United States of America, Spain, India, China, Denmark, Italy, France, United Kingdom, Portugal etc. The installed capacity for different countries and the actual electricity generation by using wind mills are shown in tables 1 and 2 in the appendix.

While traveling across Germany can see the landscape doted with wind mills. This shows sincerity of Germany towards an eco-friendly energy generation system. It is not surprising, therefore, that Germany leads the world in terms of installed capacity (~ 22.25 GW in 2007) and actual energy generation (~ 39.5 TWh in 2007) which is approximately 6.8% of total electricity generation (~ 570 TWh in 2007)in the country. Denmark produces over one fifth of its total electricity by using wind mills and this is the maximum proportion of wind energy to total electricity generation for any country. There is great thrust in European Union on producing electricity through wind mill turbines, because this is very clean technology (Mancisidor, p. 100).

Developing countries like India and China are also rapidly joining the club of countries producing significant amount of electricity through wind mills. In 2007, India ranked fourth in terms of total installed capacity ahead of China and one of the largest global suppliers of wind mill turbines is also an Indian multinational – Suzlon.

Not only the current growth rate but the potential growth rate in the installed capacity and electrical power generation through wind mills is also very bright. Buoyed by various tax incentives and tax holidays plus the associated carbon credit trading potential many companies in developing countries are going gung ho in installing huge wind farms. Another benefit in the developing countries like India and china is huge short fall in electricity. For developed nations this route of electricity generation offers a way out to reduce the carbon emission and meet the mandatory carbon emission limits as per Kyoto protocol.

Advantages of Wind Power

There are many advantages associated with electricity generation through wind mills, some of these are briefly discussed below:

1. Scalability: One can have a very small isolated wind mill to cater to the needs of a small household; a medium sized wind mill to cater to the needs of a medium sized installation like a school, hospital etc as well as a chain of large wind mills to cater to a large industry or to supply to a grid. This scalability is very helpful in electrifying the remote rural areas and is of special significance to poor as well as developing countries (Whale pp 425).
2. No emission: Wind mill produce no harmful gas or greenhouse gas and therefore are clean source of electricity. There is no active waste as well like that in case of nuclear industry. Therefore, this technology is an effective technology to counter atmospheric pollution as well has greenhouse effect.
3. Perpetual source of energy: Wind energy is perpetual source of energy and therefore, there is no fear that this resource will end one day. Therefore, this is most reliable as far as the energy resource of our future generations.
4. Equitable distribution: This source of energy is almost equitably distributed world over and therefore, there can be no monopoly etc of this God gifted energy resource. This is probably the most positive aspect of wind energy.

However, everything is not rosy about wind energy. There are some limitations as well and some limitations are briefly discussed below:

Limitations of Wind Energy

1. Non uniform and uncontrolled electricity generation: The input of a wind mill turbine is the wind velocity and output is electricity. As input keeps varying so does the output. With reduced wind speed electrical output of a wind turbine decreases and vice versa. We do not have any control over wind velocity and therefore, no control over the electricity generation from a wind mill turbine. This poses some problems regarding reliability and in case of a household unit one may have to use an inverter and a battery in case he needs electricity when wind is blowing slowly.
2. Huge space requirements: Wind farms require huge space and therefore, are not affordable to a region where land cannot be spared as there is heavy pressure on land to cultivate crops to feed the population. This is relevant for countries with high population density like India, Pakistan, Bangladesh etc. Due to this reason many countries in the world are focusing on off-shore wind farms.

Conclusion

It can be concluded that while energy is must for our survival, wind energy as a seemingly perpetual source of energy is the potential answer to the energy security of our generations to come. Not only this is perpetual source of power, this is non-polluting as well and will protect our planet the Earth from global warming. This offers great scalability and therefore, it can be distributed in a much easier way and will prove very helpful in electrifying the rural areas of the poor and developing countries.

References

1. Whale J. “Design and construction of a simple blade pitch measurement system for small wind turbines”. Renewable Energy 34 (2009) 425–429.
2. Itziar Martý´ nez de Alegrý´ a Mancisidora,_, Pablo Dý´ az de Basurto Uragaa, In˜ igo Martý´ nez de Alegrý´ a Mancisidorb, Patxi Ruiz de Arbulo Lo´pez. “European Union’s renewable energy sources and energy efficiency policy review: The Spanish perspective”. Renewable and Sustainable Energy Reviews 13 (2009) 100–114.
3. Wind_power. 

Appendix

Table 1: Installed capacity of wind mill turbines world over (MW)

Table 2: Annual Wind Power Generation and Total Electricity Generation in TWh