Sources of Energy
Energy is derived from various sources. The various renewable and non-renewable energy sources, its uses, advantages and disadvantages are briefed here.
Green Energy Awareness Video.
Energy is the capacity of a physical system to perform work. Energy exists in several forms such as heat , kinetic or mechanical energy, light, potential energy , electrical, or other forms. Energy is the ability to do work. Energy sources could be classified as Renewable and Non-renewable.
Renewable energy is derived from natural processes that are replenished constantly such as solar, wind, ocean, hydropower, biomass, geothermal resources, and biofuels and hydrogen.
Sun is the primary source of energy. Sunlight is a clean, renewable source of energy. It is a sustainable resource, meaning it doesn't run out, but can be maintained because the sun shines almost every day. Coal or gas are not sustainable or renewable: once they are gone, there is none left. More and more people are wanting to use clean, renewable energy such as solar, wind, geothermal steam and others. It is called 'Green Power'. It lights our houses by day, dries our clothes and agricultural produce, keeps us warm and lots more. Its potential is however much larger
- It is a perennial, natural source and free
- It is available in plenty
- It is non-polluting
- It does not emit any green house gases.
- Solar energy offers decentralization in most (sunny) locations, meaning self-reliant societies.
- One of the biggest advantages of solar energy is the ability to avoid the politics and price volatility that is increasingly characterizing fossil fuel markets.
- It doesn’t result in the destruction of forests and eco-systems that occurs with most fossil fuel operations.
- Dependent on change in seasons / weather – hence they may not be used always
- Requires high initial investments for productive use
- Solar systems doesn’t work at night directly but the battery bank, which stores energy during day-time can be used during night.
- Solar electricity storage technology has not reached its potential yet.
- Solar panels are bulky. This is particularly true of the higher-efficiency, traditional silicon crystalline wafer solar modules.
Technologies for productive use of solar energy
Solar energy can be used to generate electricity. Through Solar Photovoltaic (SPV) cells, solar radiation gets converted into DC electricity directly. The generated electricity can either be used as it is or can be stored in the battery. The stored electrical energy can be used when solar energy is not available. SPV is nowadays successfully used for home and street lighting and water pumping in villages. In hilly areas, solar water heating is also being used.
Wind is the natural movement of air across the land or sea. The wind when used to turn the blades of a wind mill turns the shaft to which they are attached. This movement of shaft through a pump or generator produces electricity. The Potential for wind power generation for grid interaction has been estimated at about 1,02,788 MW taking sites having wind power density greater than 200 W/sq. m at 80 m hub-height with 2% land availability in potential areas for setting up wind farms @ 9 MW/sq. km. India now has the 4th largest wind power installed capacity in the world which has reached 36089.12 MWp (as on May, 2019). Private agencies own 95 % of the wind farms in India.
- It is environment friendly
- Its freely and abundantly available
- High investment requirement
- Wind speed is not uniform all the time which affects power generated
Biomass and Biofuels
What is biomass?The plants fix solar energy through the process of photosynthesis to produce biomass. This biomass passes through various cycles producing different forms of energy sources. For example, fodder for animals that in turn produce dung, agricultural waste for cooking, etc. The current availability of biomass in India is estimated at about 500 million MT per annum, with an estimated surplus biomass availability of about 120 – 150 million metric tones per annum covering agricultural and forestry residues. This corresponds to a potential of about 18,000 MW. An additional 9131.50 MWp power was generated through bagasse based cogeneration in the country’s Sugar mills.
UsageBiomass is an important source of energy accounting for about one third of the total fuel used in our country and in about 90% of the rural households. The widespread use of biomass is for household cooking and heating. The types of biomass used are agricultural waste, wood, charcoal or dried dung.
- Available locally and to some extent abundantly
- It is a relatively clean fuel when compared to fossil fuels. In a way biomass also cleans our environment by trapping carbon- di-oxide
- Drudgery involved in collection of fuel
- During indoor cooking and in the absence of sufficient ventilation fuels such as dung cause air pollution which is a serious health hazard
- Unsustainable and inefficient use of biomass often leads to destruction of vegetation and hence environmental degradation.
Technologies for productive use of biomass
Technologies that enable efficient use of biomass are becoming prevalent in rural areas.The efficiency of fuel usage is increased by:
Biofuels are predominantly produced from biomass feed stocks or as a by-product from the industrial processing of agricultural or food products, or from the recovery and reprocessing of products such as cooking and vegetable oil. Biofuel contains no petroleum, but it can be blended at any level with petroleum fuel to create a biofuel blend. It can be used in conventional healing equipment or diesel engine with no major modification. Biofuel is simple to use, biodegradable, non-toxic and essentially free of Sulphur and aroma.
Water and geothermal
The flowing water and the tides in the sea are sources of energy. India is endowed with large hydropower potential of 1,45,320 MW. Heavy investments are made on large projects. In recent years, hydel energy (through mini and small hydel power plants) is also used to reach power to remote villages which are unelectrified. The estimated potential of Small Hydro Power is about 15,000 MW in the country. As on May 2019, the installed capacity of Small hydro projects (upto 3MW) amounts to 4603.75 MW.
Advantages of Small Hydro Power as an energy source
- Reliable, eco-friendly, mature and proven technology.
- More suited for the sensitive mountain ecology.
- Can be exploited wherever sufficient water flows -along small streams, medium to small rivers and also harness abundant sun-shine, wind-energy and other bio-energy sources.
- Does not involve setting up of large dams or problems of deforestation, submergence or rehabilitation.
- Non-polluting, entails no waste or production of toxic gases, environment friendly.
- Small capital investment and short gestation period.
- Minimal transmission losses.
- With careful planning and adoption of simplified and standardized designs, SHP installations are becoming increasingly competitive with thermal, diesel or gas based power generation.
Oceans cover 70 percent of the earth’s surface and represent an enormous amount of energy. Although currently under-utilised, Ocean energy is mostly exploited by just a few technologies: Wave, Tidal, Current Energy and Ocean Thermal Energy.
- Tidal Energy : The tidal cycle occurs every 12 hours due to the gravitational force of the moon. The difference in water height from low tide and high tide is potential energy. Similar to traditional hydropower generated from dams, tidal water can be captured in a barrage across an estuary during high tide and forced through a hydro-turbine during low tide. The capital cost for tidal energy power plants is very high due to high civil construction and high power purchase tariff. To capture sufficient power from the tidal energy potential, the height of high tide must be at least five meters (16 feet) greater than low tide. Total identified potential of Tidal Energy is about 12455 MW, with potential locations identified at Khambat & Kutch regions, and large backwaters, where barrage technology could be used.
- Wave Energy : Wave energy is generated by the movement of a device either floating on the surface of the ocean or moored to the ocean floor. Many different techniques for converting wave energy to electric power have been studied. Wave conversion devices that float on the surface have joints hinged together that bend with the waves. This kinetic energy pumps fluid through turbines and creates electric power. Stationary wave energy conversion devices use pressure fluctuations produced in long tubes from the waves swelling up and down. This bobbing motion drives a turbine when critical pressure is reached. Other stationary platforms capture water from waves on their platforms. This water is allowed to runoff through narrow pipes that flow through a typical hydraulic turbine. The total theoretical potential of wave energy in India along the country’s coast is estimated to be about 40,000 MW – these are preliminary estimates. This energy is however less intensive than what is available in more northern and southern latitudes.
- Current Energy : Marine current is ocean water moving in one direction. This ocean current is known as the Gulf Stream. Tides also create currents that flow in two directions. Kinetic energy can be captured from the Gulf Stream and other tidal currents with submerged turbines that are very similar in appearance to miniature wind turbines. Similar to wind turbines, the movement of the marine current moves the rotor blades to generate electric power.
- Ocean Thermal Energy Conversion (OTEC) : Ocean thermal energy conversion, or OTEC, uses ocean temperature differences from the surface to depths lower than 1,000 meters, to extract energy. A temperature difference of only 20°C can yield usable energy. Research focuses on two types of OTEC technologies to extract thermal energy and convert it to electric power: closed cycle and open cycle. In the closed cycle method, a working fluid, such as ammonia, is pumped through a heat exchanger and vaporized. This vaporized steam runs a turbine. The cold water found at the depths of the ocean condenses the vapor back to a fluid where it returns to the heat exchanger. In the open cycle system, the warm surface water is pressurized in a vacuum chamber and converted to steam to run the turbine. The steam is then condensed using cold ocean water from lower depths. OTEC has a theoretical potential of 180,000 MW in India subject to suitable technological evolution.
Geothermal Energy is heat stored in earth crust and being used for electric generation and also for direct heat application. Geothermal literally means heat generated by earth. Various resource assessment carried out by agencies established the potential 10600 MWth /1000MWe spread over 340 hot springs across seven Geothermal provinces/11 states.
The availability of geothermal power is most environment-friendly power, round the year 24x7 basis, not affected by the severity of climate during 6 to 7 winter months like hydro and like dependence on sun in solar PV.
To view the Geothermal database of India, click here.
Non Renewable energy
Coal, Oil and Natural gas are the non-renewable sources of energy. They are also called fossil fuels as they are products of plants that lived thousands of years ago. Fossil fuels are the predominantly used energy sources today. India is the third largest producer of coal in the world, with estimated reserves of around 3,19,020.33 million tonnes of Geological Resources of Coal (as of 1.4.2018). Coal supplies more than 70.87% of the country's total production of energy by commercial sources. India consumes about 245 MT of crude oil annually, and more than 70% of it is imported. Burning fossil fuels cause great amount of environmental pollution.
Source : Portal content team
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