Energy crisis and its environmental impact
Energy may be defined as any property, which can be produced from or converted into work. In today’s world for any development and for all industrial operations, energy is a prerequisite. Life is unthinkable without energy. Energy production and energy utilization are the indicators of a country’s progress. Heat, light, electricity are different forms of energy. While energy drives the world, the energy generated and utilized affects environment on a phenomenal scale. More population, rapid industrialization, increased energy generation, over production, uncontrolled consumption and damages to environment are all inter-linked issues. Major issues are slowly being converted into crisis threatening our survival.
Background history of energy usage:
Fire was probably the first human energy technology. Charcoal from fires has been found at sites occupied by our early ancestors. Wind and waterpower have been used early as long. Muscle power provided by domestic animals has been important for agriculture. The invention of the steam engine, together with diminishing supplies of wood in industrializing
countries caused a switch to coal as our major energy source in the nineteenth century. Coal in turn, has been replaced by oil in this century due to the ease of shipping, storing and burning liquid fuels. Recently electricity and gas (petrol) has changed the economic prosperity and lifestyle in many countries.
Renewable and non-renewable energy sources
Energy sources that are being made available continuously are known as renewable energy sources. (Eg). geothermal energy, wind energy, tidal energy, solar energy, ocean currents, nuclear fusion, gobar gas, biomass and vegetable refuse etc.Non-renewable sources of energy – those sources, which are being accumulated in nature from a very long time and cannot be replaced if they are exhausted. (Ex). Coal, ores, petroleum, timber, natural gas, electricity
etc. Fossil fuels like petroleum, natural gas and coal are now providing about 95% of all commercial energy in the world.
Energy crisis is due to the increase in population accompanied by rapid urbanization and industrialization. Our resources of petroleum and natural gas are dwindling day by day. We can hardly expect the oil industry to operate at full capacity until the last drop is removed from the ground. It appears that we will run out of petroleum and natural gas by about 2020 unless domestic supplies are extended by taking one or more of the following steps.
Steps to be taken to resolve energy crisis
1.Reduce the consumption of fuels : The principal target areas are heating and transportation, which account for about 18% and 25% respectively, of our total energy requirements. The consumption of fuel in these areas can be reduced by (a)proper insulation of existing buildings and design changes in new constructions (eg. using less plate glass), (it saves about 33% of energy) (b)improving the fuel economy of automobiles, (c) using more efficient means of transportation.
2. Develop new sources of energy: The energy crisis has prompted the development of alternate energy sources (alternatives to fossil fuels) other than the heat available from the combustion of fossil fuels.
(a)Wind Energy :
In India, the wind power is of great significance as there are large coastal, hill and desert areas where wind energy can be usefully exploited for generation of electricity and water pumping.
The harnessing technology of wind energy is simple. The strike of the blowing wind on a specially designed blades of a windmill’s rotor causes it to rotate. This rotation, which is the mechanical energy, when coupled to a turbine, drives the power generator. The wind energy thus delivers on the spot small quantities of energy. The Indian subcontinent is a high wind zone
with energy potential estimated at about 20,000 MW. Wind farms are already located in Tamil Nadu, Gujarat, and Andhra Pradesh. Advantages of wind power : i.Power generation is cheaper. Power is procured at 40 paise per unit ii. free from pollution and environmental degradation, iii. Since generation is continuous unlike in diesel power, investment is never idle.
(b) Geothermal Energy
Geothermal energy is fast emerging as a significant source of electricity in several island nations, mainly in the Indian oceans and the Pacific regions. Geothermal plants make use of naturally heated steam drawn to the surface through a series of boreholes.
Hot Rocks for energy generation
The Hot Dry Rock (HDR) technology is especially suitable for countries like India, where the geological pattern favours easy exploitation of this source. Tapping of energy involves drilling of holes several km deep into the earth where the temperature of rocks ranges form 200 – 250oC.
Water is pumped into these bore holes and allowed to circulate through the source rock’s fracture net work, which may have fissures barely a few millimeter wide. This water is then ejected under pressure from a second hole in the form of steam. The steam is used to power turbines for electricity generation, after which it is condensed back to water that can be used again.
(c) Mini hydel generation
Energy generation from small water source is probably the most cheapest and reliable of all renewable energy sources. It can be harnessed conveniently from nearby canal or stream in a most environmentally benign manner. Nature has been very generous and bounteous in providing a vast hydro electric potential to the Indian subcontinent.
(d) Ocean energy
The various methods of extracting energy from oceans are as follows. 1.Ocean winds, 2.Ocean waves, 3.Ocean tides, 4.Ocean currents, 5.Ocean geothermal, 6.Ocean Thermal Energy Conversion (OTEC), 7.Salinity gradient and 8.Bioconversion of sea weeds. India’s first power plant generating electricity from ocean energy is commissioned at Vizhinjam fishing harbour in Kerala to provide energy of 150 MW in a year.
Tidal energy : Ocean waves and tides contain large amount of energy. Tidal energy is important because it is renewable, pollution free and more stable in comparison with hydroelectric power which is dependent on monsoon cycle. Tidal power plants are being designed in the Bay of Canada, Kutch in India etc where tides have been found to be in the right range. (e) Solar energy:
Solar energy is another energy source. Each year the earth receives from the sun an enormous total of 5 × 1020 k.cals of energy. Solar energy, which is the primary source of all energy forms on the earth, is the renewable form of energy.
Advantages of solar energy:
(a) Solar energy is a kind of universal, decentralized and non-polluting energy (b) it helps considerably in maintaining the ecological balance through the process of photosynthesis and green house effect. (c) it has none of the disadvantages found in the combustion of fossil fuels such as coal, oil or gas.
(f) Nuclear energy :
Nuclear energy is the only energy source, known to be economically feasible in the present and for the near future. It can replace fossil fuels. In nuclear fission, a heavy atom splits under neutron bombardment into smaller fragments, with the evolution of huge amount of energy. In spite of this advantage the problem of disposal of nuclear wastes remains. Nuclear fusion is expected to be an ideal energy source for the future. In nuclear fusion, light nuclei such as deuterium (2 1H) and tritium (3 1H) combine to form heavier stable nuclei. Moreover, the products of fusion are not radioactive and so safety hazards associated with fission reactors are greatly reduced. The light isotopes needed for fusion are sufficiently common to supply all of our energy needs for hundreds of years. Unfortunately, the above fusion reaction has not been perfected to sustain flow of energy.
(g) Bio gas or Gobar gas:
Gobar gas plants are based on anaerobic fermentation of organic wastes in the absence of air. Through gaseous stage the heating efficiency of the cattle dung increased production by about 20%. There is a production of an organic manure which is about 43% better than dry cattle dung itself. This manure can also reduce pressure on naptha-based fertilizers. It has been estimated that 10m3 of biogas has energy equivalent of 6.0 m3 of natural gas, 3.6 litres of butane, 7.0 litres of gasoline or 6.1 litres of diesel fuel.
(h) Hydrogen – Source of power for future
The hydrogen has been found to be a good choice among all the alternative fuel options. It can be produced in virtually unlimited quantities with on hand production technologies. It has been established that hydrogen can meet all the energy needs of human society, including power generation more efficiently and more economically than petro fuels, and with total compatibility with the environment. In addition, hydrogen is non-toxic, reasonably safe to handle, distribute and use as a fuel. Hydrogen has the highest mass energy content – its heat of combustion per unit weight is about 2.5 times that of hydrocarbon fuel, 4.5 times that of ethanol and 6.0 times
that of methanol. Its thermodynamic energy conversion efficiency of 30-35% is greater than that of gasoline (20-25%).
1. Thermal Power
The air, water and soil pollution caused by these plants in terms of fly ash, CO2, SO2, NO2 and particulates etc. is becoming unacceptable in the environmentally conscious society.
Hydro-electric power generation is associated with displacement and resettlement of human population from the site of hydel plant to other places. This leads to considerable human problems causing considerable delay in the implementation of the project and escalation of its cost. New dams built may affect the ecosystem of the locating sites.
Radioactive pollutants released form nuclear power plants are chronically hazardous. The commissioning of boiling water power reactors (BWRS) have resulted in the critical accumulation of large number of long lived radionuclides in water. Environmentalists argue that thermal effluents from nuclear reactors have acutely affected the aquatic eco system. The dangerous radioactive waste cannot be buried in land without the risk of polluting soil and under ground water. Several well publicised accidents (Ex. Chernobyl disaster at former U.S.S.R.) and radiation episodes have given a lot of fear in the mind of general public regarding the radiation hazards.
4. Solar energy
The use of solar energy, from the environmental viewpoint, is a completely safe operation. However, the sites for larger installations of solar power plants should be selected without reducing the forest cover. Cadmium, used in fabricating thin film solar cells, is both poisonous and a possible carcinogen. Carbon dioxide produced while forming silicon from silica may increase the atmospheric temperature causing green house effect. Silicon dust is also an important occupational hazard.
The burning of coal, oil, wood, dung cakes and petroleum products would cause environmental problems. (1)The increase in CO2 concentration is largely responsible for green house effect and global warming, while (2) disposal of fly ash requires large ash ponds and may pose a severe problem (3)The smoke produced by burning of wood, agricultural by-products or animal’s dung cake causes respiratory and digestive problems and may also lead to eye and lung diseases. (4) Nitrous oxide, Sulphur di-oxide and CO2 can cause acid rain.