VERTICAL AXIS TURBINE Most of the world's energy resources are from the sun's rays hitting earth. Some of that energy has been preserved as fossil energy, some is directly or indirectly usable; for example, via wind, hydro- or wave power. Renewable energy is generally electricity supplied from sources, such as wind power, solar power, geothermal energy, hydropower and various forms of biomass. The popularity of renewable energy has experienced a significant upsurge in recent times due to the exhaustion of conventional power generation methods and increasing realization of its adverse effects on the environment. Facts from the World Wind Energy Association estimates that by 2010, 160 GW of wind power capacity is expected to be installed worldwide which implies an anticipated net growth-rate of more than 21% per year.

Before the 21st century, wind was primarily used to pump water from wells and to grind grain, but over the last twenty years the cost of wind energy has dropped by more than 80 percent, turning it into the most affordable form of clean energy. Recent advances have allowed for sophisticated wind technologies, which previously sat in the mind of thoughtful engineers and inventors, to be developed into cost-effective, reliable solutions. For a small wind turbine to be effective, it must produce energy across a wide range of wind speeds. It must be able to generate energy from winds that are switching directions and gusting. Wind power harnesses the power of the wind to propel the blades of wind turbines.These turbines cause the rotation of magnets, which creates electricity. Wind towers are usually built together on wind farms.

A wind turbine extracts energy from moving air by slowing the wind down, and transferring this energy into a spinning shaft, which usually turns a generator to produce electricity. The power in the wind that’s available for harvest depends on both the wind speed and the area that’s swept by the turbine blades. Vertical-axis wind turbines (VAWTs) are a type of wind turbine where the main rotor shaft is set transverse to the wind (but not necessarily vertically) while the main components are located at the base of the turbine.

Two types of turbine design are possible – Horizontal axis and Vertical axis. HORIZONTAL WIND TURBINE VERTICAL AXIS WIND TURBINE In horizontal axis turbine design, the tower is higher and more blade design parameters have to be defined and yaw system is required. In vertical axis turbine, no yaw system is required and there is no cyclic load on the blade, thus it is easier to design. Maintenance is easier in vertical axis turbine

VAWTs offer three big advantages that could reduce the cost of wind energy A lower turbine center of gravity reduced machine complexity and better scalability to very large sizes. A lower center of gravity means improved stability afloat and lower gravitational fatigue loads. Additionally, the drivetrain on a VAWT is at or near the surface, potentially making maintenance easier and less time-consuming. Fewer parts, lower fatigue loads and simpler maintenance all lead to reduced maintenance costs.

Power generation efficiency 50- 60% Above 70% PARAMETER HAWT VAWT Starting speed 2.5- 5 m/s( high) 1.5- 3 m/s( low) Tip speed ratio 5-7 1.5-2 Power generation efficiency 50- 60% Above 70% Electromagnetic interference Yes No Steering mechanism of wind Gear box Above 10 KW/yes Blade rotation speed Quite large Quite small Wind resistance capability weak Strong (can withstand a typhoon up to 12-14 class) Noise 5- 60 dB 0- 10 dB Failure rate High Low Maintenance Complicated Convenient Rotating speed low

CONCLUSION: As the structure is very simple wind can be used at higher efficiency, without complex phase modulation Institutions. It can start smoothly and run at low wind speeds and low noise. It can be said as a direction of development of wind turbines. VAWT’s can be placed much closer to the ground( say on top of a normal building of 20 meters ).

Thank you