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Conventional and Non-Conventional Sources of Energy

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Conventional and Non-Conventional Sources of Energy

India is the fourth largest consumer of energy in the world after USA, China and Russia but it is not endowed with abundant energy resources. It must, therefore, meet its development needs by using all available domestic resources of coal, uranium, oil, hydro and other renewable resources, and supplementing domestic production by imports.

Social, economic and scientific developments are directly linked to the development of energy resources. However, the present stock of energy resources of the world is limited and can last only for a few decades. Moreover most conventional energy sources are non-renewable. Hence, mankind is searching new source of energy and the development of renewable sources of energy along with the rational use of existing non-renewable energy and their conservation.

Energy resources are classified into conventional and non conventional forms on the basis of their use. Conventional or non-renewable sources are those especially coming from the fossils and which cannot be re-used once exhausted like coal, petroleum, wood, etc.

However non-conventional or renewable sources, as the name suggests are inexhaustible pool of energy, ready at every moment to be used or re-used like tidal energy, wind energy, biomass energy, etc.

Key Differences Between Conventional and Non-Conventional Sources of Energy

The difference between conventional and non-conventional sources of energy are presented below in points:

  1. Conventional sources of energy, as the name suggests, are those sources which are widely used all around the world since ages. On the contrary, non-conventional sources of energy are described as the energy sources whose evolution has been done in the recent past and has gained popularity since then.
  2. As the conventional sources of energy are limited in nature, and their formation takes millions of years, they can be exhausted one day. Conversely, non-conventional sources of energy are the sources that are in abundance in the environment and are easily renewable, so they are inexhaustible.
  3. Conventional sources of energy pollute the environment on a large scale through the smoke and hazardous waste emitted from the power plants. However, the energy produced from running water does not pollute the environment. On the other hand, non-conventional sources of energy are environment-friendly, so they do not harm the nature, by polluting it.
  4. The energy produced from conventional sources are highly used for industrial and commercial purposes. As against, the energy generated out of non-conventional sources are used for domestic purposes.
  5. Conventional sources of energy are costly because they are scarce but their uses are unlimited. In contrast, non-conventional sources of energy are less expensive, because of their enormous presence in nature.
[Source-key differences between conventional and non-conventional sources of energy]


Conventional or Non-renewable Sources


 Coal and Lignite:

Coal is the major source of energy. Coal is the mainstay of India’s energy sector accounting for over 50 per cent of primary commercial energy supply in 2010–11.

The gap between the demand and the domestic supply of coal has made it imperative to augment domestic production both from the public sector and the private sector and to expedite the reform process for realising efficiency gains through increased competition in the sector during the 12th Plan.

Lignite production was 20.44 million tonnes in 2005-06. According to an estimate, coal reserves in India would last about 130 years.

The target for coal production at the end of the 11th Plan was initially set at 680 million tonnes and revised downwards to 630 million tones at the time of the MTA. The actual achievement was only 540 million tonnes. Since demand in the terminal year (2011–12) of the 11th Plan was around 640 million tonnes there was a large demand–supply gap of 100 million tonnes which was only partially met by imports.

This adversely affected the coal supplies to end consumers, particularly the power sector. It is estimated that out of capacity addition of 41,894 MW, around 25,000 MW of coal-based capacity commissioned is being sub-optimally utilized because of inadequate availability of domestic coal.

As on March 31, 2012 the estimated reserves of coal was around 293.5 billion tones, an addition of 7.64 billion over the last year.  The states of Jharkhand, Odisha, Chhattisgarh, West Bengal, Andhra Pradesh, Maharashtra and Madhya Pradesh account for more than 99% of the total coal reserves in the country.

Major coal fields in India are Raniganj, Jharia, East Bokaro and West Bokaro, Panch-Konkan (Tawa Valley), Singrauli, Takhar, Chanda-Wardha and Godavari Valley.

Types of Coal On the basis of characteristics, heating value, carbon and volatile matter, coal is divided into mainly the following types:

a) Anthracite (hard coal)

  • It is hard, black, lusturous, shiny and dense.
  • This is the highest grade coal with calorific value of 8,250 to 8,700 kcal/kg.
  • It contains 86-98% of carbon.
  • Volatile matter is low being just 2-14%.
  • It is not found in India. It mainly occurs in UK & USA.
  • It is used in industrial furnaces, graphite electrodes and in metallurgical processes.

b) Bituminous (Soft coal)

  • It is also high grade coal next to anthracite.
  • It has a calorific value in the range of 7,500 to 8,700 kcal/kg. It contains about 46-86% carbon.
  • Volatile matter is low and can be removed by heating in the absence of air, when it gets converted into coke. More the volatility, lower is the heating value.
  • It is used for combustion, hydrogenation, gasification, blending, domestic use and metallurgy.

C) Lignite (Brown coal)

  •  It is inferior quality, low grade coal.
  • It has laminar (banded) structure with woody, fibrous, brownish black appearance, resembling wood, hence thename. In Latin, Lignum means wood.
  • Its calorific value is 6,150 to 7,300 kcal/kg.
  • It has a moisture content of about 30-50% before exposure to air.
  • Its volatile matter is about 30%. Lignite when exposed to air gets oxidised.
  • Due to high moisture, rapid oxidation and low heating value, it is not economical to transport it to distant places.
  • It is burned in pit head power plants.

d) Peat

  • Peat is a solid fuel with highest moisture content.
  • It is not fully matured form as it is partially decomposed, so
  • it is not true coal.
  • Its heating value is much less and is lower than that of wood.
  • It has about 90% moisture.It is used as a low grade fuel.


Oil and Natural Gas:

Petroleum is derived from dead animals that lived in remote past. Natural gas has also been produced in the Earth’s crust by similar processes and this is also a combustible fuel.

In India, efforts made by the Oil and Natural Gas Corporation (ONGC) and Oil India since the late 1950s have led to the identification of a number of oil and gas deposits both offshore and onshore. The onshore fields were mainly discovered in the Mumbai, Gujarat, Assam and Arunachal Pradesh; and the offshore fields in the sea were notably the Mumbai High fields such as North and South Basin and South Tapti.

Natural gas is primarily methane (CH4). Like coal and oil, it is a fossil fuel. It was given off by decomposing plant and animal remains that were buried in the earth by sedimentary deposits for millions of years. That is why, natural gas deposits often accompany coal and oil deposits.

At normal temperature and pressure, the contents of commercial natural gas are mainly methane (CH4, ethane (C2H6) and varying amounts of propane (C2H8) and butane (C4H10). An average composition of natural gas indicates methane-83.0%, ethane 7.2%, propane-2.3%, butane-1.0%, N2-5.8%, CO2- 0.2% etc.

There are mainly two sources of natural gas. It occurs in gas fields i.e. underground reservoirs similar to oil reserves and is recovered by drilling gas wells. In addition, large quantities of gas are produced in association with the production of crude oil.

In order to meet burgeoning demand for petroleum products in the country, the Ministry of Petroleum & Natural Gas has taken several measures to enhance exploration and exploitation of petroleum resources including
natural gas and Coal Bed Methane (CBM), apart from improved distribution, marketing and pricing of petroleum products.

The Government of India launched the ninth bid round of New Exploration Licensing Policy (NELPIX) and fourth round of Coal Bed Methane Policy (CBM-IV) during October 2010 to enhance the Country’s energy security. In addition, in order to supplement domestic reserves the oil and gas PSUs have acquired assets abroad, the production of oil and natural gas of ONGC- VIDESH Ltd during 2011-12 was 8.75 MMT of oil and equivalent gas (MMTOE) from its assets abroad.

Hydrogen-CNG Fuel Centre

The Renewable Energy Ministry on 7th June,2007 unveiled a Rs 25,000 crore roadmap to promote use of hydrogen, with an estimated one million vehicles using it as fuel by 2020 and the gas being used to fire electricity generation units for an aggregate 1,000 mw of electricity.

As part of the new initiative, a demonstration project for setting up a hydrogen dispensing set- up at a petrol pump in Delhi has been sanctioned as a joint venture with Indian Oil Corporation. The project would enable dispensing of neat hydrogen and CNG blended with hydrogen as fuel for vehicles. The station will have a hydrogen generation capacity using an electrolyser system and facilities for storing and dispensing neat hydrogen as well as blended with CNG in varying ratios.

The H-CNG blends will be used in the modified CNG vehicles and are expected to further reduce emissions from such vehicles as compared to when burning only CNG. The project would also generate operational experience in handling hydrogen as an automotive fuel.


In the long run, new and renewable sources of energy will be necessary since the reserves of conventional fuels, such as, oil and coal are limited in the world and the pressure on their availability and prices will steadily mount as demands increase. Even in India, at the current level of production, coal is expected to last for only 245 years, oil for 21 years and natural gas for another 38 years.

Renewable sources of energy include solar, wind, water, geothermal, ocean, hydrogen, biomass and solid waste. They are relatively quickly renewed and recycled in nature and hence constitute sustainable energy sources. They are also referred to as non-conventional energy sources because the techniques for their exploitation have been developed comparatively recently.

In the country, the systematic efforts to harness the renewable energy sources were initiated only after setting up of the Commission in 1981 for Additional Sources of Energy (CASE) and in 1982 the Department of Non-Conventional Energy Sources (DNES).

The Ministry of Non-Conventional Energy Sources (MNES) created in 1992, is the nodal agency of the Government of India for all matters relating to nonconventional/renewable energy.

Solar Energy

The Sun provides us enormous amounts of energy in the form of solar radiation-energy that travels in small wave packets called photons, reaching the surface of the Earth from a distance of 93 million miles. Radiation energy is released due to thermo-nuclear fusion going on continuously in the Sun.

The solar energy reaching per square metre of the Earth’s atmosphere is called the ‘Solar Constant’ and is
equal to 1.36 KW in 12 hours.

The total energy being received by the atmosphere is about 1.5×1018 KWh per day. It is believed that with just 0.1% of the 75000 trillion KWh of solar energy that reaches the Earth, the energy required by plants can be satisfied. Application of solar energy can broadly be sub-divided as follows:

  1. Conversion of solar energy into heat.
  2. Conversion of solar energy directly into electricity.
  3. Conversion of solar energy to plants, vegetable or other biological forms and application of solar energy to convert these forms into usable forms of fuel. This may broadly be termed as bio-energy.
  4. Indirect application of solar energy, such as, harnessing of winds, waves, temperature gradients from the ocean, etc.

Wind Energy

Wind energy is the kinetic energy associated with movement of large masses of air resulting from the differential heating of the atmosphere by the Sun. Hence, wind energy is nothing but the converted form of solar energy. It is estimated that about 106 to 107 MW of usable power is continuously available in the Earth’s winds. Though the total quantity of this resource is extremely large, it is concentrated in certain regions, and can vary a great deal with time at given location. For the utilization of wind energy, the speed of wind must be between 8 to 22 m per second. Wind energy is renewable and possess no major environmental threats.

A total capacity of 18,420 MW has been established up to December 2012 in the country. India is now the fifth largest wind power producer in the world, after China, USA, Germany and Spain. As per Indian Wind Atlas, the on-shore wind power potential has been estimated as 49,130 MW at 50 m height.

Wind Energy Conversion: The shaft power from the wind turbine can be utilized for a wide variety of purposes, including electricity (AC & DC generation), direct pumping, direct mechanical work, etc. The most common wind turbine system involves a tower mounted multi- bladed rotor facing into the wind, rotating around a horizontal axis and turning an electrical generator or a mechanical gearbox connected to its axis. The maximum power that can be extracted from a wind turbine is 59.3 per cent.

Water Pumping Windmills: Small windmills with direct mechanical drive matched to a pump and tank storage are in extensive use in many parts of the world. These hold significant potential for pumping water irrigation, drinking needs, etc. Improved types of soil water pumping windmills have also been developed in several countries, including India.

Wind Electric Conversion Systems: Wind energy is a high-quality form of mechanical energy that can be converted into electrical energy with minimal energy losses. Since the rotor of a windmill moves periodically, the output may be obtained in the form of alternating current either by using a gearbox or fixing the rotational speed or by allowing speed variations and transforming the generated electrical power


Ocean Energy

The sea, which is constantly receiving solar radiations and acts as the world’s largest natural solar collector, has potential to provide a means of utilizing renewable energy. It acts not only as collector, but also has an enormous storage capacity. Energy from the ocean is available in several forms such as ocean thermal energy, wave energy, tidal energy, salinity gradients, ocean currents, ocean winds and bio-mass.

Ocean Thermal Energy Conversion

There exists a temperature difference of the order of 20°C between the warm surface water of the sea and the cold deep water, and this natural temperature difference can be used to generate energy. In one OTEC plant, the warm water from the surface with the temperature of 24 to 30°C is brought into one pipe and the cold water at the temperature of about 4 to 8°C is brought in another pipe in the depth of about 1000 metres. These two pipes are used in conjunction with fluid such as ammonia, propane or neon.

The warm water evaporates liquid ammonia into vapour at high pressure and is made to pass through a turbine which rotates it and generates electricity. The ammonia vapour coming out of the turbine is condensed back into liquid ammonia by cooling it with the cold sea water brought up from the deep part. The liquified ammonia is then pumped back to the evaporator, thus, completing the cycle, which can then run continuously.

Energy from OTEC can be converted into either electrical, chemical or protein form. These plants could be combined with energy intensive industries like ammonia, hydrogen or aluminium production. Furthermore, OTEC plants can be combined with aquaculture or desalination for obtaining fresh water.

The cold water from the deeper sea which is rich in nutrients can be placed in a lagoon or lake where these nutrients can help to raise fish, oysters or other types of biological life.

Being a tropical country, India has the OTEC potential of about 50,000 MW. The most promising site identified so far is on the Lakshadweep Islands where the necessary geographical conditions for a shore-based OTEC plant exist. In these islands, the alternative cost of producing electricity by transporting diesel from the main land as is being done at present, is very high. India has also tied up with a US- firm to set up an OTEC Plant in Tamil Nadu.


Tidal Energy

Tides are created by the combined gravitational effect of the Earth, the Moon and the Sun. Though the tide is the universal phenomenon of the Earth’s sea-water body, some regions are more favourable for the establishment of such power plant for the commercial production of tidal energy. Primary requirements for the construction of an installation having a capacity over 200 MW are

  • an average tide of 5-12 metres;
  • the possibility of linkage to a grid in order to accommodate the variable power output of the tidal plant;
  • favourable geographical location and favourable socio-economic and ecological conditions. Bulb type turbines as used in conventional hydro-electric stations have proved to be reliable for generating power from the tides.

In India, three potential sites have so far been identified, namely, the Gulfs of Kutch and Cambay on the west coast in Gujarat and the Sunderbans along the east coast in West Bengal.

According to the estimates of the Indian government, the country has a potential of 8,000 MW of tidal energy. ‘Central Electricity Authority’ in India has the overall responsibility for developing it.
A power plant of 600 MW capacity is proposed to be set up in the Gulf of Kutch.

The Gujarat government is all set to develop India’s first tidal energy plant. In 2012, the state government had approved Rs. 25 crore for setting up the 50 MW plant at the Gulf of Kutch.


The National Hydro-Electric Power Corporation (NHPC) was incorporated in 1975 with the objectives to plan, promote and organise the integrated development of hydro-electric power.

NHPC Limited presently has an installation base of 5295 MW from 14 hydropower stations on ownership basis,
including projects taken up in Joint Venture.

Some important hydro-electric power projects constructed by NHPC are at Salal and Dulhasti
(both in J&K), Tanakpur (Uttarakhand), Chamera (HP), Baira Siul (HP), Chutak (J&K), Teesta Low Dam – III (W.Bengal), Sewa – II (J&K), Teesta – V (Sikkim), Omkareshwar (MP), Dhauliganga – I (Uttarakhand), Indira Sagar(MP), Rangit (Sikkim), Uri – I (J&K), and Loktak (Manipur).

India is blessed with immense amount of hydro-electric potential and ranks 5th in terms of exploitable hydro-potential on global scenario. As per assessment made by CEA, India is endowed with economically exploitable hydro-power potential to the tune of 1,48,700 MW of installed capacity.

Today, about 23 per cent of the total electric power in the world comes from hydropower.

India is endowed with economically exploitable and viable hydro potential assessed to be about 84,000 MW at 60 per cent load factor (1,48,701 MW installed capacity).

In addition, 6780 MW in terms of installed capacity from Small, Mini, and Micro Hydel schemes have been
assessed. Also, 56 sites for pumped storage schemes with an aggregate installed capacity of 94,000 MW have been identified. However, only 19.9 per cent of the potential has been harnessed so far.

The total hydro-electric potential in India has been estimated at about 472×109 kilowatt hours or 472 terawatt hours normally. But, we have exploited only a little more than 19 per cent of the total potential. In addition, it is also estimated that an annual energy generation of about 25 terawatt could be obtained economically through mini and micro-hydels, coal drops and other possible low- head developments.

A centre for the development and demonstration of alternate small hydro technologies has been set up at Roorkee University by the Department of Non-Conventional Energy Sources for development of newer and more economic designs of micro-hydel units, water mills and hydrams.

Several field projects in Haryana, Himachal Pradesh, Uttar Pradesh and Jammu and Kashmir are being initiated to utilise the potential availability of canal drops, falls, run- off-river systems, etc.

NHPC Limited is presently engaged in the construction of 10 projects aggregating to a total installed capacity of 4502 MW. Given the renewed thrust on development of hydro power in the country, NHPC Limited has drawn up a massive plan to add over 10,000 MW of hydropower capacity by the end of XIIth Plan(year 2017).

The National Projects Construction Corporation (NPCC) was set up in 1957 as a joint venture of central and state governments as a construction-contracting agency for the execution of multipurpose river valley projects,
power projects and other heavy engineering projects.

As a part of diversification plan, the Corporation proposes to take up the work of transmission lines also.


Geothermal energy is the exploitation of heat energy of Earth within 10 km of the Earth’s upper crust. Geothermal energy can be processed for generation of power, where the geothermal fluid has a temperature of 130°C.

Geothermal manifestations are widespread in India in the form of 340 Hot Springs localities.Only a few direct utilization schemes have been launched by various agencies. They are in Puga, Chhumuthang, Manikaran and Bakreshwar. Of these, India’s most promising geothermal field is in Puga valley in Ladakh. There are number of geothermal wells drilled in the valley.

Tattapani in Madhya Pradesh is another promising geothermal area in India.



Compressed Natural Gas or CNG is a cleaner alternative to the liquid petroleum. CNG
is already in use in countries such as the USA, Japan, Italy, Brazil and New Zealand.

In Delhi, the Supreme Court has directed the operation of city buses exclusively on CNG fuel mode.The
government on its part launched CNG pilot project in Delhi as early as 1993.

Thanks to this project, CNG is now available in the NCR and most cities of the country.
CNG is cleaner fuel than the conventional fuel (petrol and diesel) as far as PM is concerned.

Further, CO, HC and NOX emission for CNG based car are lower because of the catalytic
converter fitted with them.

Gasohol: It is a mixture of absolute alcohol and petrol and is being tried as a fuel to run a
car. A programme of 5 per cent blending of ethanol with petrol is already underway with
effect from November 2006 targeting 20 States and 4 UTs.

Subject to availability, the percentage of blend can be enhanced to 10 per cent as
specification for petrol with 10 per cent ethanol blend is already given by the BIS. At present,
the EBP Programme is successfully running in 14 States and three UTs; OMCs have been able
to contract 55.87 crore litres of ethanol against the requirement of 105 crore litres of ethanol
for 5 per cent blending in the entire notified area.

The Mysore Sugar Company of Madya tried out a 25:75 proportion mix of absolute alcohol
and patrol for maximum efficiency. A fuel economy of 3 to 5 per cent has been reported
when gasohol is used as a fuel.



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