On the other hand the electricity demand does not cope with such variations. (Komor, 2009) • Other forms of barriers: There are some other obstacles like allowing challenges of renewable power plants and technical hazards with regard to transmission connecting to the plant, higher proportion of capital to operating costs and policy instability. (Komor, 2009)

The prime concern over using renewable energy sources like solar & wind energy relates to dependability, economic feasibility and sustainability, which must be considered thoroughly at the time of erecting as well as during the maintenance of electrical power plants. The Photo Voltaic is applied to enhance solar energy and transform it readily into electricity and the wind generators would convert the mechanical energy to electricity with the help of an electricity generator. Since the Photo Voltaic Cells depend mostly on the presence of sunlight the solar power is subjected to great challenge. Electric output tends to increase in morning hours and is at its high during the mid day and reduces in the evening. It is also pertinent to note that both the types of energy sources are not readily available when needed and it is necessary to maintain backup systems to ensure uninterrupted supply. With the introduction of a hybrid system keeping both the solar and wind plants as supplementing to each other could improve their energy production capacity, thereby improving the supply dependability and total performance. (Yiew; Singh; Singh, 2011)

(3) Description of a Typical Installation:

Reported facts reveal that the wind turbine installation has attained 30% growth and reaching an installed capacity of 160 GW in the year 2010. While USA has an installed capacity of 39 GW, the corresponding figures of Germany and China are 26 GW each. Besides, other countries like Spain, India and Italy has a sizeable installed capacity. These countries have a high wind speed rate of more than 12 m/s. A 'Wind Turbine Energy Conservation -- WECS' includes electronics-power components, wind turbine, control system and network systems. A mini scale of WECS consists of an installed capacity of less than 10KW which is suitable for low speed geographies. The critical part in the WECS happens to be wind turbine. The kinetics energy is converted into mechanical energy and thereafter into electrical energy. The fluctuated value of kinetics energy is dependent on the air density and wind speed. The production of mechanical energy is linked to the 'incoming wind energy.' However, in areas where the wind speed is low, extraction of wind power constitutes a challenge. (Musyafa; Negara; Robandi, 2011)

To generate an optimal wind power, a pitch angle of the wind turbine blade is required to be found out precisely. This includes the type of wind turbine and the blades used. The advantages are many wherein the wind speed is high. In these areas the pitch angle position varies with regard to the incoming wind speed so as to attain maximum wind power. A wind turbine installation consists of a wind turbine with three blades -- a motor servo, gear blade, and a generator besides a host of allied components. The blade is built on an air foil contour standard relating to NACA. The blade type is being chosen keeping in mind it's symmetrical and easiness of the fabrication procedure. The blades are made of fiber material and a gear box is attached to it which can achieve a movement resolution of 5.6 degrees. (Musyafa; Negara; Robandi, 2011)

(4) Speculation on the future of Wind Power Technology:

The present challenges to higher usage of wind power are forecasting of wind availability, grid integration, visual impact and public outlook. For offshore wind energy, an important problem involves reducing costs. However, the varying nature of wind electricity makes it difficult for wind energy to completely replace other sources of electricity. While wind turbine comprises of only a tiny miniscule of generation facility, their levels of intermittency is rarely noticed by system operators who are being used to adjusting the output to sudden changes in demand. During times of higher uses, the marginal value of the wind energy nevertheless is equivalent to the cost of the fuel and other marginal operating expenses of power plants that undergo...

However, if wind energy is able to be stored in an efficient manner, it could become competitive. (Princiotta, 2011)
Even though wind power is already competitive in a lot of locations based on electricity production costs, the additional expenses associated with grid integration and backup capacity must also be taken into account. With increased governmental support for its development, wind power might assume to be generally competitive with conventional technologies by 2015 and 2020. The deep water offshore component in the total wind power will increase, especially if shallow sites in the Europe as well as in U.S. are tapped early. (Princiotta, 2011)

If the past capacity generation is any indication, the future of wind turbine will see additional capacity creation and up-gradation of technology. During the bygone two decades, the average wind turbine ratings have increase almost on a linear fashion and the present commercial machines are being rated at 1.5MW to 2.5MW. Most of the wind turbine designers made predictions that their machines were as large as they can ever be. Nevertheless, with every new generation of wind turbines, the size has increased on a linear fashion and also has experienced reductions in 'life-cycle cost of energy.' (Thresher; Robinson; Veers, 2008)

The long-term initiative to develop larger turbines arises from the desire to derive benefit from wind shears by means of placing rotors in the higher, increased energetic winds at increased height from the ground since wind speed increase with rise in ground height. Due to this, the capacity factor of wind turbines in the U.S. has increased in course of time. But there are constraints to this continued growth overall, as it costs more to build larger turbines. The main case for a size limit for wind turbines is focused on the "square-cube law." This principle states that as the wind turbine rotor increases in size, the energy output also enhances as the 'rotor-swept area', whereas the volume of material, and thus its mass and cost rises as that of the cube of the diameter. (Thresher; Robinson; Veers, 2008)

To put it in simple terms, for some sizes, the cost for a larger turbine will grow at a faster rate compared to the resulting energy output revenue thereby increasing scaling unfavorable. Design engineers have been able to circumvent this rule through alteration of the design rules by increasing size and eliminating material or through use of material in a more efficient manner in order to cut down on the issues of weight and cost. Latest research have shown that of late, blade mass has been rising at approximately a factor of 2.3 in place of the anticipated 3. If advanced research and developmental progress are able to provide even better design procedures, as also new materials and production methods that permitted the complete turbine to increase with the diameter squared, in that case it would be feasible to go for greater innovation. (Thresher; Robinson; Veers, 2008)

Resistance of the public to wind firms is considered another challenge. There have been severe objections to wind turban erection due to visual, noise and environmental disturbances. Public resistance occurred both to large and small scale wind turbine projects. A specific controversial fight has been witnessed in Nantucket Sound, wherein a wind farm of 130 wind turbans was to be erected by a private development company. Small wind turbines are accumulating increased focus since they are producing power at reduced wind speeds. The increasing efficacy in lower wind speed regions has been the matter of in depth study presently. However, even small wind turbines have met with opposition if they are positioned at close proximity to residential places. (Rodman; Meentemeyer, 2006)

It is important that such varied features are analyzed so that site suitability is comprehended prior to construction. An evaluation of probable locations for development of wind power is necessary for energy policy planning, since it will permit predictions of the level that wind energy can be advanced considering the varied geographic limitations. Identifying the most potential regions would reduce the contentions and develop public views relating to wind power. Studies have also revealed that in those areas wherein wind turbans have been erected, acceptance of the public has been gained over time. This factor needs to be incorporated in any models that involve public perceptions. Additional elements to be incorporated in future are zoning regulations and proximity to the area of power grid. (Rodman; Meentemeyer, 2006)

Exhibit -- I

Enercon E-112- the World's largest wind turbine with a rotor diameter of 112 m and power generation capacity of 4.5MW

Exhibit -- II

Working Principle of a Wind Turbine

Exhibit -- III

Generating systems used in Wind Turbines

(Top -- Squirrel Cage Induction generator

(Middle- Doubly-fed Wound Rotor induction Generator

(Bottom- Direct drive Synchronous Generator)