Write a note on Solar Energy?

Solar energy is the most readily available abundant source. It is free as it does not belong to anybody. It is also non-polluting. Solar energy has the greatest potential of all sources of renewable energy. Only if a small amount of this form of energy could be used, it will be one of the most important supplies of energy especially when other sources in the country are being rapidly depleted. It is estimated that the sun gives us 1000 times more power than we need. If we can use even 5 per cent of this energy, it will be 50 times what the world will require. Solar energy is being used in many part of India for cooking by using the so called ‘solar cookers’.

Solar Cooker

The solar energy can be used directly to give us hot water during winter. This procedure is used in hotels and industrial establishments to get hot water.

Solar water heating system

Solar run refrigerators have been developed for rural areas. These keep vegetables, fruits fresh for a longer period. This procedure has great potential for using solar energy for cold storage. It can also be used for room heating in colder regions. These days, high multistory building use more glass in buildings to trap sun’s heat. This has lot of potential even in less sunny climates.

Solar energy can be used with the help of ‘photo voltaic cells’ for producing electricity for driving vehicles and for illumination. In solar facility, hundreds of mirrors are used to focus sun’s energy on a central collector; which in turn attains extremely high temperatures these are useful for the production of electricity or industrial applications.

Solar Energy flow through ecosystem: 

The basic source of energy is from sunlight. The green plants through the process of photosynthesis, convert radiant energy of the sun into chemical energy. The portion of the radiant energy absorbed by the green plants and stored in the form of chemical energy is the food energy. It should be understood that out of enormous amount of energy continuously radiated by the sun is reflected or refracted back by the atmosphere surface of the earth and other objects. Only about one per cent of the solar energy received by the plant is used through the process of photosynthesis.

The plants can grow by converting the sun energy directly into their tissues. The plants are used by herbivores (the primary consumers) as food which give them energy. A large part of this energy is used up for the metabolic functions of these animals, such as breathing, digesting food, supporting growth of tissues, maintaining blood flow and body temperature. Energy is also used for activities, such as looking for food, finding shelter, breeding and rearing the young ones.

When the primary consumers (the herbivores), in turn may be eaten by a carnivore (the secondary and tertiary consumer), the energy is transferred from a primary consumers to a secondary or a tertiary consumer. In this way, transfer of energy takes place from one level to the other. The process of transfer of energy in a food chain is called energy flow.

About 10 per cent of the energy available in one tropic level is transferred to the next tropic level. If the secondary level receives 10 per cent of the energy of the producer, the tertiary level captures 10 per cent of this energy. This is referred to as 10 per cent law. Due to this 10 per cent law we find less number of carnivores as compared to herbivores. Of course, it is much easier to find plants in the ecosystem The energy loss at each trophic level is due to several factors as:

  • Organisms use energy in respiration and other metabolic activities
  • Some organisms are not consumed by the next tropical level and therefore, get decayed and decomposed.
  • Some of the food energy eaten by the organisms is not assimilated and passed out of the body.

The figure below shows that the biological pyramid of an ecosystem depicting the number of organisms and energy available at each tropic level.

Biological Pyramid in an ecosystem.
In the above biological pyramid note the following points:
  • Some part of solar energy dissipates as it passes through the ecosystem.
  • A small portion of the solar energy is captured by, the plants (producer).
  • At each trophic level, a part of the energy is captured from previous tropical. This is because at each energy level some energy is used for metabolish purposes and also some goes to decompose-rs. Due to this type of energy transfer not much energy is left after 4 or 5 levels
  • The number of organisms is also reduced as we go up the tropic levels.
The flow of energy from the sun in the ecosystem can be represented as shown below
Energy movement in an ecosystem

Tags: B.Sc

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