Use of any given energy source in human society encounters limits to expansion. At the beginning of the 21st century some issues have achieved global dimension. Principal fossil energy sources, such as oil and natural gas are approaching exhaustion that may occur within the span of a generation. The renewable energy sources capture their energy from the existing flows of energy, from on-going natural processes such as sunshine, wind, flowing water, biological processes and geothermal heat flows. The Tide energy is one of the important renewable and sustainable sources of energy as its available seamlessly from the ocean. Though, we haven’t fully recognized and utilized for electricity generation due to high construction cost and its ecological effects. We will discuss about the Tide energy in detail to understand the various aspects.
As per World Energy Council 2001 survey; the ‘Potential exploitable wave energy’ resources worldwide to be 2 TW and the wave market is estimated at $ 800 billion worldwide. Tidal energy comes from the gravitational forces of the Sun and the Moon on the Earth’s bodies of water, creating periodic shifts in these bodies of water. These shifts are called Tides. If the Moon and the Sun are in the same plane as the Earth, the tidal range is the superposition of the range due to the lunar and solar tides. This results in the maximum tidal range (spring tides).
The Tidal power is not a new concept and has been used since at least the 11th century in Britain and France for the milling of grains. The hydro power that converts the energy of Tides into electricity is called TIDAL POWER. The larger the tidal influence, the greater the displacement of water and therefore the more potential energy that can be harvested during power generation. One of the main advantages of tidal energy is its predictability and regularity due to the known climatic conditions thanks to the technological revolution in digital weather forecasting. The global climate change should only increase its generating capacity due to higher ocean levels. The Tidal energy is completely carbon neutral like wind or hydro energy. The counties who has bigger coastline can exploit the maximum tidal energy for electricity. There are a number of places around the world that have adopted pilot projects for different types of tidal generators. We can extract two types of tidal energy, kinetic energy of currents between ebbing and surging tides and potential energy from the difference in height between high and low tides. Therefore, a tidal energy generator must be placed in a location with very high-amplitude tides. The simplest generating system for tidal plants is known as an ebb generating system, involves a dam (a barrage) across an estuary. The different Tidal power systems are Tidal Fences, Tidal Lagoons, Dynamic Tidal generators and Tidal stream generators. The various turbines are used in Tidal power like Bulb type, Rim type and Tubular type turbines. These systems are implemented based on the geographical location, the length of coastline, construction cost, energy needs and political consensus between the countries.
The renewable source of Tidal energy can offer significant advantages, including improved transportation due to the development of traffic or rail bridges across estuaries and reduced greenhouse gas emissions by utilizing Tidal power instead of fossil fuels. The turbines can be submerged in the water and therefore out of sight. It doesn’t pose a problem for navigation and shipping. The Tidal turbines are vastly better than wind turbines in terms of efficiency. A 1 MW tidal turbine can access five to ten times of energy per square meter of rotor than a 1 MW wind turbine, resulting in a smaller and potentially lower cost machine. The investment payback of Tidal turbines is much faster than most other renewable energy sources. However, there are some environmental concerns that need to be addressed when developing this technology further. Potentially the effect a tidal station has on the plants and animals which live within the estuary and some fish will be unable to escape the water speed near a turbine and will be sucked through. The power generated doesn’t match with the time of demand and it produces power for only about 10 hours a day. The cost of building a Tidal power plant can have a high capital cost e.g. an 8000 MW with $15 billion cost in UK and 2200 MW with $3 billion cost in Philippines are built. The operating cost of Tidal power generation is low as it runs without fossil fuels instead uses kinetic and potential energy of water.
To make the Tidal energy more acceptable and attractive to the people, we have to make the cost lower so that it can be built in a larger scale. The turbine design has to be more effective, the technology of its working process should be fully developed and never neglect the environment impacts of Tidal power generation. We must find out a way to solve the current problems which are discussed above for the sustainable and long lasting renewable energy source in future.