Energy resources :

• As man’s needs increased, several changes took place in the use of energy resources and devices.
• Energy resources can be classified in many ways such as conventional and non-conventional, renewable and non-renewable, substance-based and process-based, etc.

Substance-based energy resources :

Substance-based energy resources are biotic. Availability of these resources is limited. The use of these resources leads to pollution. These resources cause damage to the environment.

Wood :

• In villages, wood is used on a large scale for cooking and earthen stoves.

Coal :

• Plant and animal bones were buried long ago owing to earth movements.
• They were then disintegrated by tremendous pressure and heat, leaving only carbon remaining. Coal was created as a result of this process.
• Low quality coal is used for cooking and coke and high quality coal is used in industries and thermal power stations.

Mineral oil and natural gas:

• Mineral oil is found under land surface and also below the ocean floor.
• In most of the mineral oil wells, reserves of natural gas are also found.
• Mineral oil reserves are limited in nature however it is in greater demand, Therefore its cost is very high.
• Mineral oil is also called black gold due to its blackish colour and high cost.
• Mineral oil and natural gas are used in thermal power generation.

Biogas :

• Biogas can be generated from biotic waste materials such as faeces of animals, dead leaves, shells, etc.
• This energy can be used for domestic needs such as cooking,heating water lighting lamps, etc.
• Some farmers have raised biogas plants in their own yards to cater to their domestic needs.

Energy from waste material :

• Waste generated in metropolitan cities can be segregated to use the biotic component to generate gas.
• This gas can be used to generate power.
• In future, this may help to solve the problem of waste disposal in cities, also the cities can become Self-reliant in terms of their power requirement.

Atomic energy :

• Splitting of the atoms of minerals like uranium and thorium can be used for power generation.
• In this process, using very small quantities of minerals, energy can be generated on a very large scale.
• Only few countries like India, U.S.A., Russia, France and Japan use atomic energy.

Process-based energy resources :

Process-based energy resources are abiotic. Availability of these resources is unlimited. The use of these resources does not lead to pollution. These resources are environment-friendly.

Hydel power :

• Hydel power is the power obtained from the kinetic energy of running water.
• Hydel power does not cause any degradation of the environment. Also, the water used in generating power can still be used again.

Wind energy :

• Nowadays, wind energy is being utilized for power generation.
• For power generation, a wind speed of 40 to 50 km/h is required.
• Due to this wind speed, the blades of the windmills turn, generating kinetic energy. This kinetic energy is further converted into electricity.
• This electricity can be used for agriculture, domestic use and industries.

Solar energy :

• We get light and heat from the sun.
• India is located in the torrid zone. Therefore, it has a lot of scope for using solar energy.
• Devices like cookers, lamps, heaters, vehicles, etc. can be run on solar power.
• The generation of solar power depends on the intensity of sunrays and the duration of sunshine.

Tidal energy :

• Sea Waves and tides are movements of ocean water that go on continuously.
• A technology has now been developed to generate power with the help of the Speed and force of sea waves.
• The kinetic energy of sea waves and tides is converted into electricity.
• This energr is pollution-free and everlasting.
• It can be used on a large scale in a peninsular country like India.

Geo-thermal energy :

• The temperature in the earth's interior increases by 1°C at a depth of every 32 metres.
• Man has now developed a process whereby this underground heat can be utilized to generate power.
• One such project is located at Manikaran, Himachal Pradesh in India.

The need for using energy frugally :

• The demand for energy is increasing all the time due to growing population urbanization and the growing needs of man.
• It is necessary to use alternative and non-conventional energy resources.
• Therefore, it is necessary to use energy frugally.