Non Conventional Sources of Energy – Science Class 10

With technological progress, our demand for energy is increasing day by day. With the demand for energy growing at the current rate, one can’t just depend on the limited and non-renewable reserves of the conventional sources of energy. So, there is a need to look out for new alternate sources of energy. These alternative sources of energy are also known as Non-conventional sources.

Some important examples are:

  1. Solar energy
  2. Energy from the sea
  3. Ocean thermal energy
  4. Geothermal energy
  5. Nuclear energy

Solar Energy

The sun has been radiating an enormous amount of energy at the present rate for nearly 5 billion years and will continue doing so for another 5 billion years to come. Of the total energy radiated, only a small part of solar energy reaches the earth’s surface.

Devices such as a solar cooker or a solar water heater function by tapping solar energy. To absorb maximum heat, these devices have black surfaces. Some solar cookers are also fitted with mirrors to focus the rays of the sun in order to achieve higher temperatures.

They are covered with a glass plate to trap the heat radiations and facilitate heating. But an associated limitation of using these solar devices is that these devices can be used only at certain times during the day. This limitation of using solar energy is overcome by the use of solar cells that convert solar energy into electricity.

A typical solar cell develops a voltage of 0.5-1 Volt and can produce about 0.7 Watts of electricity when exposed to the sun.

Now, let us see what a solar panel is! A large number of solar cells combine in an arrangement to deliver enough electricity for practical use. This arrangement of solar cells is called a Solar Panel. Now, let us have a look at the various advantages of using solar cells.

The principal advantages are:

  1. Solar cells have no moving parts
  2. They require little maintenance
  3. They can work without the use of any focusing device
  4. The solar cells can also be set up in remote and inaccessible areas (where the lying of the power transmission line is expensive and commercially not viable). But there are also some limitations of using solar cells.

The manufacturing cost of solar cells is very expensive due to certain reasons such as:

  1. The availability of special grade silicon that is used in making solar cells is limited
  2. The use of silver for interconnecting the cells in the panel further adds to its cost

This limits the use of solar cells for domestic purposes. However, they are used as the main source of energy in Artificial satellites

Some other examples where solar cells are used are:
• In radio or wireless transmission system or TV relay station in remote locations
• In traffic signals
• Calculators

Energy from the Sea

We have already learned about solar energy, one of the major sources of non-conventional energy. Let us now learn about energy from the sea which is another potential non-conventional source of energy. Oceans are large water bodies covering 70-80 percent of the earth’s surface.

The energy from the sea can be harnessed in three different forms-

  1. Tidal Energy
  2. Wave Energy
  3. Ocean Thermal Energy

Tidal Energy: The rise and fall in the water level in the sea due to the gravitational pull of the moon on earth results in a phenomenon called High tide and low tide respectively.

The energy derived from these rising and falling ocean tides is called tidal energy. To harness this energy, a dam is constructed across a narrow opening to the sea. The turbine fixed at the opening of the dam converts this tidal energy to electricity. Do you know the largest tidal power plant is built on the River Rance in France? Tidal energy is an inexhaustible and pollution-free source of energy.

Another important form of energy derived from the sea is Wave Energy. The energy from the ocean waves is also used for the rotation of turbines and thus, the production of electricity. You must be aware of how these waves are generated. The unequal solar heating of the earth generates winds and these winds when blow over water generates waves. Like tidal energy, it is also a renewable and pollution-free source of energy.

Ocean Thermal Energy

Now let us discuss another important form of energy- The Ocean Thermal Energy. The oceans and the seas are reservoirs of large amounts of solar energy. This solar energy stored in the oceans in the form of heat is called OCEAN THERMAL ENERGY (OTE). The sun warms the ocean water at the surface and the wave motion mixes the warmed water downwards to a depth of about 100 meters.

The temperature difference between the layers at the surface and those at a depth of 100 meters ranges from 10° Celsius to 30° Celsius. This difference in temperature between the surface and the deeper water layers in the ocean is used to generate electricity. But how? The warm surface water vapourises volatile liquids like ammonia.

These vapors are then used to run turbines of generators to produce electricity. The cold water from the depth is pumped to the surface which again condenses back the ammonia vapors to liquid. This process of harnessing the thermal energy of the oceans for the generation of electricity is called Ocean Thermal Energy Conversion (OTEC) and the devices used for the purpose are called OTEC power plants. The electric power generated from OTEC is continuous, renewable, and pollution-free.

Geothermal Energy

Due to geological changes, molten rocks formed in the deeper hot regions of the earth’s crust are pushed upward and trapped in certain regions called “hot spots”. When the underground water comes in contact with hot spots, steam is generated. Sometimes hot water from such regions finds an outlet at the surface which is known as hot springs.

The steam generated at hot spots trapped in the rocks is employed in generating electricity by routing it to a turbine through a pipe. Geothermal energy is the naturally occurring thermal energy of the earth that originates with the rock formation, from radioactive decay of minerals, and from solar energy absorbed at the surface.

Geothermal energy is a clean and sustainable form of renewable energy which is also cost-effective and environment friendly. Though relatively inexpensive, the number of commercially viable hot spots is very few, thus rendering the exploitation of geothermal energy difficult. In India, the North-Western Himalayas and the Western Coast are regions with important geothermal sites.

Nuclear Energy

The energy trapped inside the nucleus of an atom is called nuclear energy or atomic energy. There are two distinct ways of generating nuclear energy. These are:

  • Nuclear fission
  • Nuclear fusion

Read More- Sources of Energy: Conventional and Non-Conventional | Types of Energy

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