Active use of solar energy
- Active solar heating and cooling systems rely on solar collectors which are usually mounted on roofs. Such systems also requires pumps and motors to move the fluids or blow air by fan in order to deliver the captured heat. A number of different active solar heating systems are available. The main application of these systems is to provide hot water, primarily for domestic use. Active solar heating is extensively used in India, Japan, Israel, Australia and Southern United States having sunny climate.
Solar energy to produce electricity
Solar energy is used to generate high temperature heat or electricity. Solar collectors in sunny deserts can produce high temperature heat to spin turbines for producing electricity but cost of such devices are high. Several solar thermal systems can collect and transform radiant energy received from the sun into high temperature thermal (heat) energy, which can be used directly or converted into electricity. Huge arrays of computer-controlled mirrors called heliostats track the sun and focus sunlight on a central heat collection tower
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| Huge arrays of computer-controlled mirrors called heliostats track the sun and focus sunlight on a central heat collection tower. | |
Definition of pollution and pollutants
- Pollution may be defined as addition of undesirable material into the environment as a result of human activities. The agents which cause environmental pollution are called pollutants. A pollutants may be defined as a physical, chemical or biological substance unintentionally released into the environment which is directly or indirectly harmful to humans and other living organisms.
TYPES OF POLLUTION
Pollution may be of the following types:
- Air pollution
- Noise pollution
- Water pollution
- Soil pollution
- Thermal pollution
- Radiation pollution