Energy resources, Growing energy needs, Renewable and non-renewable energy sources

ENERGY RESOURCES
Energy may be defined as "any property which can be converted into work"
Energy is defined as "the capacity to do work"

Energy is available on earth in a number of forms and some forms may be used immediately while others might require some transformation. It is difficult to imagine Life without energy. All the developmental activities in the world are directly or indirectly dependent on energy. Both energy production and energy utilization indicate a country's progress.

GROWING ENERGY NEEDS
Energy is essential to the existence of mankind. All industrial processes like mining, transport, lighting, heating and cooling in buildings need energy. With the growing population, the world is facing an energy deficit. Lifestyle change from simple  to a complex and luxurious lifestyle adds to this energy deficit. Almost 95% of commercial energy is available from fossil fuels like coal and natural gas. These fossil fuels will not last for more than a few years.Hence, we must explore alternative fuel/energy options.

RENEWABLE AND NON-RENEWABLE ENERGY ENERGY SOURCES
Based on continual utility, natural resources can be classified into two types:

Renewable energy sources: These resources can be generated continuously and are inexhaustible. 

Ex: Wood, Solar energy, Wind energy, Hydro power, tidal energy, Geo-thermal energy, etc

Merits of Geo-thermal energy:

1. Unlimited supply
2. Provides energy security
3. Fits in the concept of sustainable development
4. Reliable and devices are modular in size
5. Decentralized energy production

 Non-renewable energy sources: Non-renewable energy sources are natural resources, that cannot be regenerated once they are exhausted. They cannot be used again.
Ex: Coal, Petroleum, Natural gas and Nuclear fuels