`ul"Tidal Energy"`
Due to the gravitational pull of mainly the moon on the spinning earth, the level of water in the sea rises and falls. If you live near the sea or ever travel to some place near the sea, try and observe how the sea-level changes during the day.
This phenomenon is called high and low tides and the difference in sea-levels gives us tidal energy. Tidal energy is harnessed by constructing a dam across a narrow opening to the sea.
A turbine fixed at the opening of the dam converts tidal energy to electricity. As you can guess, the locations where such dams can be built are limited.
`ul"Wave Energy"`
Similarly, the kinetic energy possessed by huge waves near the seashore can be trapped in a similar manner to generate electricity.
The waves are generated by strong winds blowing across the sea. Wave energy would be a viable proposition only where waves are very strong. A wide variety of devices have been developed to trap wave energy for rotation of turbine and production of electricity.
`ul"Ocean Thermal Energy"`
The water at the surface of the sea or ocean is heated by the Sun while the water in deeper sections is relatively cold.
This difference in temperature is exploited to obtain energy in ocean-thermal-energy conversion plants. These plants can operate if the temperature difference between the water at the surface and water at depths up to `2` km is `293 K (20°C)` or more.
The warm surface-water is used to boil a volatile liquid like ammonia. The vapours of the liquid are then used to run the turbine of generator. The cold water from the depth of the ocean is pumped up and condense vapour again to liquid.
The energy potential from the sea (tidal energy, wave energy and ocean thermal energy) is quite large, but efficient commercial exploitation is difficult.
`ul" Geothermal Energy"`
Due to geological changes, molten rocks formed in the deeper hot regions of earth’s crust are pushed upward and trapped in certain regions called ‘hot spots’.
When underground water comes in contact with the hot spot, steam is generated. Sometimes hot water from that region finds outlets at the surface.
Such outlets are known as hot springs. The steam trapped in rocks is routed through a pipe to a turbine and used to generate electricity.
The cost of production would not be much, but there are very few commercially viable sites where such energy can be exploited. There are number of power plants based on geothermal energy operational in New Zealand and United States of America.
`ul"Nuclear Energy"`
In a process called nuclear fission, the nucleus of a heavy atom (such as uranium, plutonium or thorium), when bombarded with low-energy neutrons, can be split apart into lighter nuclei.
When this is done, a tremendous amount of energy is released if the mass of the original nucleus is just a little more than the sum of the masses of the individual products.
The fission of an atom of uranium, for example, produces 10 million times the energy produced by the combustion of an atom of carbon from coal.
In a nuclear reactor designed for electric power generation, such nuclear ‘fuel’ can be part of a selfsustaining fission chain reaction that releases energy at a controlled rate. The released energy can be used to produce steam and further generate electricity.
The major hazard of nuclear power generation is the storage and disposal of spent or used fuels the uranium still decaying into harmful subatomic particles (radiations).
Improper nuclear-waste storage and disposal result in environmental contamination. Further, there is a risk of accidental leakage of nuclear radiation.
The high cost of installation of a nuclear power plant, high risk of environmental contamination and limited availability of uranium makes large-scale use of nuclear energy prohibitive.
Nuclear energy was first used for destructive purposes before nuclear power stations were designed. The fundamental physics of the fission chain reaction in a nuclear weapon is similar to the physics of a controlled nuclear reactor, but the two types of device are engineered quite differently.
`"Activity 14.7"`
♦ Discuss in class the question of what is the ultimate source of energy for bio-mass, wind and ocean thermal energy.
♦ Is geothermal energy and nuclear energy different in this respect?
♦ Where would you place hydro electricity and wave energy?
`ul"Tidal Energy"`
Due to the gravitational pull of mainly the moon on the spinning earth, the level of water in the sea rises and falls. If you live near the sea or ever travel to some place near the sea, try and observe how the sea-level changes during the day.
This phenomenon is called high and low tides and the difference in sea-levels gives us tidal energy. Tidal energy is harnessed by constructing a dam across a narrow opening to the sea.
A turbine fixed at the opening of the dam converts tidal energy to electricity. As you can guess, the locations where such dams can be built are limited.
`ul"Wave Energy"`
Similarly, the kinetic energy possessed by huge waves near the seashore can be trapped in a similar manner to generate electricity.
The waves are generated by strong winds blowing across the sea. Wave energy would be a viable proposition only where waves are very strong. A wide variety of devices have been developed to trap wave energy for rotation of turbine and production of electricity.
`ul"Ocean Thermal Energy"`
The water at the surface of the sea or ocean is heated by the Sun while the water in deeper sections is relatively cold.
This difference in temperature is exploited to obtain energy in ocean-thermal-energy conversion plants. These plants can operate if the temperature difference between the water at the surface and water at depths up to `2` km is `293 K (20°C)` or more.
The warm surface-water is used to boil a volatile liquid like ammonia. The vapours of the liquid are then used to run the turbine of generator. The cold water from the depth of the ocean is pumped up and condense vapour again to liquid.
The energy potential from the sea (tidal energy, wave energy and ocean thermal energy) is quite large, but efficient commercial exploitation is difficult.
`ul" Geothermal Energy"`
Due to geological changes, molten rocks formed in the deeper hot regions of earth’s crust are pushed upward and trapped in certain regions called ‘hot spots’.
When underground water comes in contact with the hot spot, steam is generated. Sometimes hot water from that region finds outlets at the surface.
Such outlets are known as hot springs. The steam trapped in rocks is routed through a pipe to a turbine and used to generate electricity.
The cost of production would not be much, but there are very few commercially viable sites where such energy can be exploited. There are number of power plants based on geothermal energy operational in New Zealand and United States of America.
`ul"Nuclear Energy"`
In a process called nuclear fission, the nucleus of a heavy atom (such as uranium, plutonium or thorium), when bombarded with low-energy neutrons, can be split apart into lighter nuclei.
When this is done, a tremendous amount of energy is released if the mass of the original nucleus is just a little more than the sum of the masses of the individual products.
The fission of an atom of uranium, for example, produces 10 million times the energy produced by the combustion of an atom of carbon from coal.
In a nuclear reactor designed for electric power generation, such nuclear ‘fuel’ can be part of a selfsustaining fission chain reaction that releases energy at a controlled rate. The released energy can be used to produce steam and further generate electricity.
The major hazard of nuclear power generation is the storage and disposal of spent or used fuels the uranium still decaying into harmful subatomic particles (radiations).
Improper nuclear-waste storage and disposal result in environmental contamination. Further, there is a risk of accidental leakage of nuclear radiation.
The high cost of installation of a nuclear power plant, high risk of environmental contamination and limited availability of uranium makes large-scale use of nuclear energy prohibitive.
Nuclear energy was first used for destructive purposes before nuclear power stations were designed. The fundamental physics of the fission chain reaction in a nuclear weapon is similar to the physics of a controlled nuclear reactor, but the two types of device are engineered quite differently.
`"Activity 14.7"`
♦ Discuss in class the question of what is the ultimate source of energy for bio-mass, wind and ocean thermal energy.
♦ Is geothermal energy and nuclear energy different in this respect?
♦ Where would you place hydro electricity and wave energy?