After reading this article you will learn about the primary and secondary non-conventional sources of energy.

Primary Sources of Energy:

These are these which are available in nature in raw form, like coal, petroleum-oil and natural gas, wind, water at high level, uranium ore, solar radiation, geo-thermal fluid, ocean waves, ocean thermal fluid, ocean tides, biomass fluids etc. Thus primary sources include conventional and non-conventional (also known as alternatives), renewable and non-renewables.

Secondary Sources of Energy:

These are usable energy and are supplied to the user for consumption. Electrical energy, steam, hot water, LPG in cylinders or pipe-lines etc., are the examples of secondary energy sources.

Renewable energy sources are those which are renewed by the nature again and again and their supply is not affected by rate of consumption. Wind energy, solar energy, geothermal energy, ocean wave, hydro energy etc., are the renewable energies.


Alternative energy sources are those which are non-traditional. They are alternative to the conventional energy sources.

Today fossil fuel, nuclear and hydro-power sources are considered as conventional sources of energy, while others are non-conventional. The non-conventional sources including hydro power are the renewable sources of energy.

Non-renewable energy resources are those which do not get replenished after their consumption e.g., coal once burnt is consumed without replacement of the same. Therefore, the resources which are formed very slowly in nature and which are likely to be exhausted in a few more decades or centuries are called non-renewable.

Renewable energy sources like solar, wind, sea waves etc., cannot be stored in original natu­ral form. It is converted continuously to electrical form, transmitted, distributed and utilized without long term storage. The renewables are available free of cost, hence, consumption of renewables should be maximised. This may help in conserving non-renewables for some more decades/centuries.


The advantage of non-conventional energy sources are listed below:

(i) Non-depletable,

(ii) No transmission and distribution losses,

(iii) Environment friendly,


(iv) Low operation and maintenance cost,

(v) Low gestation,

(vi) Government provides lot of facilities and promotional measures,

i. 100 per cent accelerated depreciation.


ii. Five year tax holiday,

iii. Excise duty exemption,

iv. Custom duty reliefs,

v. Soft loans,


vi. Power purchase policy by states,

vii. State support.

These are well suited for decentralised use, a distinct advantage in a large country like India. Owing to technological developments and improvements in systems design it has been observed that renewable sources of energy can now be shown to be more attractive in many situations and locations. For example, calculations of the economics of bio-gas plants show that the payback period is two and half years in terms of value of fuel saved and manure produced.

According to energy experts, the non-conventional sources of energy can be used with advantage for power generation as well as other applications in a large number of locations and situations in the country. It is hoped that these alternative energy sources will be able to meet consider­able part of energy demand in coming future.


Solar energy however is not free from problems. It is not available at night and when local weather conditions obscure the Sun. Moreover solar energy is diffused in nature and is at a low potential. Consequently if solar energy is to be economically competitive it must be converted into a usable form of energy with maximum effectiveness to reduce capital cost of solar power plants.