Harnessing marine energy by horizontal axis marine turbines

Almost 80% of World's energy needs are furnished through combustion of natural resources such as oil, natural gas and coal etc. A sprawling world population implies increased demand of the energy resources. Subsequently, there has been a hike in fuel prices. Unfortunately, the planet is left to bear the brunt in form of pollution. These factors have put forward a pressing demand of research for eco-friendly and renewable resources. In this domain, tidal energy offers a promising future. Tides are produced due to the interactive orbital mechanics of solar & planetary systems. Security, diversity of supply, intermittence and predictability are few of the compelling factors in pursuit of tidal power. Tidal energy comprises of both kinetic and potential energy. The tidal stream technologies include a horizontal axis turbine and a vertical axis turbine. This study is focused on horizontal axis turbines. The horizontal axis marine turbine operates on same principles as wind turbines. The energy transformation process is quite simple. The turbine rotor is driven by the tidal current. The motion of the rotor converts mechanical energy into rotational energy. Gear box transmits shaft's rotational energy to generator which converts this energy into electricity. Shroud/ ducts/ diffuser are used to improve the efficiency of the horizontal axis marine turbine. Shroud/ ducts/ diffuser deploy diffuser and hydrofoil principles to accelerate water streamline. Power generated is proportional to cube to steam velocity. This paper aims at presenting a comprehensive review of the horizontal axis marine turbines. The study will focus on history, techniques and technologies being deployed. The author also reports the current status of development efforts related to horizontal axis turbines.