Environment UNCCD – 09
Hydro Energy or Water Power
Water power has been in use since the period of Roman Empire. Water falling from a height turns turbines at the bottom of dams to generate electricity. Presently water power is widely used all over the world and produces approximately one-fourth of the world’s electricity. Electricity produced by hydro-power is much cheaper than electricity produced by thermal power. Water power is a clean energy source as it does not cause environmental pollution and the electricity produced can be transmitted to long distances through wires or cables. But building a dam leads to several environmental problems such as submergence of plant and animal habitats and displacement of local inhabitants including tribals.
India ranks fifth in terms of exploitable hydro potential in the world. In India, generation of hydroelectric power was emphasised in the First Five Year Plan when a number of multipurpose projects such as Bhakra Nangal project on river Sutluj, Bokaro in Panchet and Talaiya in Damodar Valley and Hirakund, Rihand, NagarjunaSagar, Kosi, Koyana were launched to generate hydroelectric power, apart from their use for irrigation and other purposes.
Harvesting wind energy is possible only in the areas that receive fairly continuous winds such as islands, coastal areas and mountain passes. When gigantic fans, raised on tall towers, are rotated by the wind, its energy can be used for generation of electricity.
India occupies the fourth, after China, USA and Germany in wind power generation. Wind mills are used in Rajasthan to draw subsoil water for irrigation. Recently two wind farms of 10 MW each have been established in Tamil Nadu and Gujarat with international cooperation from Denmark.
The Ocean forms a vital source of energy. Ocean energy is obtained in various forms such as ocean tidal and wave energy, ocean thermal energy conversion
Ocean Tidal and Wave Energy: Ocean tides, produced by gravitational force of sun and moon, contain enormous amount of energy. Tidal energy is harnessed by construction of a tidal barrage. Darns built across the mouth of a river confluence with oceans, permits sea water to flow through small opening filled with propellers, connected to electric turbines. Power of ocean waves, which operates on the principle of oscillating water column, has not been exploited to its full potential except as power supplies for navigational aids. India has initiated the wave energy project off the Vizhinijam Fishery Harbour near Trivandrum in Kerala as an indigenous effort.
Ocean Thermal Energy Conversion (OTEC):
The sun warms the oceans at the surface and wave motion mixes the warm water downward to depths of about 100 meters and this mix layer is separated from the deep cold water formed at a high latitudes, by a thermocline. This boundary is sometimes marked by an abrupt change in temperature, more often the change being gradual. Thus, the resulting temperature distribution consists of two layers separated by an interface with temperature differences between them ranging from 10°C to 30°C. The higher values are found in equatorial waters. And these two enormous reservoirs in some oceanic regions provide the heat source and heat sink required to operate heat engine. The engine using this energy is referred to as OTEC which makes use of the difference in temperature between the two layers of the sea to harness energy which in turn is used to drive turbines for generating electricity.
OTEC can also be used to desalinate water, support deep water mariculture and provide refrigeration and air conditioning facilities and can prove as an aid to mineral extraction. India possesses a huge potential of OTEC which could be of the order of about 500,000 MW, about 150 per cent of the present total installed power generating capacity of the country. Some of the best global OTEC sites are situated off the Indian mainland and near the islands of Lakshadweep, Andaman and Nicobar. In India, an ocean energy cell has been developed at IIT, Chennai to keep pace with the international developments in this area. A US company, M/S Sea Solar Power Inc., is promoting the use of OTEC and the world’s first plant in India is proposed off the coast of Tamil Nadu capacity of 100 MW.
The natural heat from the interior of earth can usefully be converted into energy. This natural heat comes from the fission of radioactive material present in the rocks in the interior of the earth. Natural internal heat of the earth was harnessed by geo-hydro-thermal conversion, hot igneous and geo-pressured systems. Presently, there are several geothermal plants working successfully in USA, New Zealand, Russia, Japan, Mexico and California. Heated groundwater flowing upwards as hot water stream and hot springs-the nature’s geysers, can be used to turn turbines and generate electricity. In India, natural geysers are common in Kullu and Manali, Manikarn, Sohana and some other places. Assessment of geothermal energy potential of selected sites in Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Jharkhand and Chhattisgarh is being undertaken.
Energy from biomass and biofuels
The biomass formed by the photosynthesis process serves as a primary fuel as well as secondary fuel. The processing of biomass ad its further utilization makes it a secondary fuel. Many countries, including India, are exploring biomass as an alternative energy sources. Since the discovery of fire, bioenergy has been one of the most widely used forms of renewable sources of energy worldwide. Biomass provides fuel flexibility to match a broad range of energy demands. It can be stored and has a benefit over other sets of renewable energies. Presently, all types of biomass collectively provide nearly 14% of the global primary energy supplies and represent almost 80% of the world renewable energy share. In some of the developing countries, the major share is from bioenergy (around 90% of energy supply), with the use of traditional biomass for cooking and heating (UNEP, 2016).