Studies indicate that about 78–80% of the world commercial energy comes from fossil fuels, such as, petroleum, coal and natural gas. Those high-carbon sources have negative effects in our environments, such as, effects on health, land, air and rain. In view of that, the attention of most countries around the globe has been shifted to alternate energy i.e. renewable energy.
Renewable energy is free source of energy, clean, affordable, and effectively infinite. It produces no emissions and results in cleaner air. Renewable energy is naturally abundant resources, which can be harnessed without compromising future energy needs. Unlike fossil fuels, which depletes as time goes on. Renewable energy sources like wind, solar, biomass, wave and tidal are abundant sources that can produce clean energy. Renewable energy generation systems like Solar, Wind and Bio are the promising and the most important renewable energy technologies. On recent time, series of renewable energy technology improvement has been witnessed, because the cost of generating electrical power is decreasing.
Although, renewable energy is considered as the new and clean technology of generating electricity, the barrier associated with renewable is stochastic and unpredictable weather behaviour. Its availability varies depending on the location. That is why, it is necessary to complement renewable with other sources like batteries. Because of this intermittent nature of renewable, single renewable energy source tends to be problematic in terms of energy yield and operational cost. Based on the aforementioned drawbacks, two or more renewable are being combined to form a hybrid renewable energy system (HRES). The main goal of doing this, are to improve electrical power production, to minimize cost, to reduce negative effects associated with burning fossil fuels and to improve the overall system efficiency.
In recent times, the integrated renewable energy system is gaining more attention, because a hybridized system can be efficiently applied to supply high efficiency and reliable electricity to the end-users, unlike a single-renewable source. A HERS can be applied in stand-alone or grid-connected modes. Stand-alone system must have a large storage to handle the load. While in a grid-connected mode, the storage can be small, and the deficient power can be acquired from the grid. It should be noted that, grid-connected mode must have a power electronic controllers for load sharing, voltage, harmonic, and frequency control.
It has been demonstrated that hybrid energy systems can significantly reduce the total life cycle cost of standalone power supplies in many off-grid situations, while at the same time providing a reliable supply of electricity using a combination of energy sources. Numerous hybrid systems have been installed across the world, and the expanding renewable energy industry has now developed reliable and cost competitive systems using a variety of technologies.
The prospects of derivation of power from hybrid energy systems are proving to be very promising worldwide. The use of hybrid energy systems also reduces combustion of fossil fuels and consequent CO2 emission which is the principle cause of greenhouse effect/global warming. The global warming is an international environmental concern which has become a decisive factor in energy planning. In wake of this problem and as a remedial measure, strong support is expected from renewables such as solar and winds.
Solar PV-Wind Hybrid System
Solar and wind power sources have experienced a remarkably rapid growth in the past 10 years. Both are pollution free sources of abundant power. Solar energy is energy from the Sun. It is renewable, inexhaustible and environmental pollution free. By adopting the appropriate technology for the concerned geographical location, we can extract a large amount of power from solar radiations.
Wind energy is the kinetic energy associated with the movement of atmospheric air. Wind energy systems convert this kinetic energy to more useful forms of power. Wind turbines transform the energy in the wind into mechanical power, which can then be used directly for grinding etc. or further converting to electric power to generate electricity. Wind turbines can be used singly or in clusters called 'wind farms'. Wind energy is almost everywhere around the world. But the wind speed strength varies depending on the particular area. Wind energy can be operates during the day and night times, unlike other renewable.
A drawback common to wind and solar system is their unpredictable nature and dependence on weather and climatic change. Both of these (if used independently) would have to be oversized to make them completely reliable, resulting in an even higher total cost. However, a merging of solar and wind energy into a hybrid generating system can attenuate their individual fluctuations, increase overall energy output, and reduce energy storage requirement significantly.
Solar-Wind hybrid power system is the combined power generating system by wind mill and solar energy panel. It also includes a battery which is used to store the energy generated from both the sources. Using this system power generation by windmill when wind source is available and generation from PV module when light radiation is available can be achieved. Both units can generate power when both sources are available. By providing the battery uninterrupted power supply is possible when both sources are idle.
Hybrid solar PV and wind generation system become very attractive solution in particular for stand-alone applications. Combining the two sources of solar and wind can provide better reliability and their hybrid system becomes more economical to run since the weakness of one system can be complemented by the strength of the other one. The integration of hybrid solar and wind power systems into the grid can further help in improving the overall economy and reliability of renewable power generation to supply its load. Similarly, the integration of hybrid solar and wind power in a stand-alone system can reduce the size of energy storage needed to supply continuous power.
As the cost of building solar PV–wind capacity continues to fall over the next five to ten years; a significant scale-up of renewable generation is a very realistic possibility in the developing world. Thousands of villages across the globe are still being exiled from electricity and energizing these villages by extended grids or by diesel generators alone will be uneconomical. Moreover, with the current resource crunch with government, these villages receive low priority for grid extension because of lower economic return potential. Standalone solar PV–wind hybrid energy systems can provide economically viable and reliable electricity to such local needs. Many countries with an average wind speed in the range of 5–10 m/s and average solar insolation level in the range of 3–6 KWh/m2 are pursuing the option of wind and PV system to minimize their dependence on fossil-based non-renewable fuels.
