Sources of energy

SOURCES OF ENERGY

 

1. ENERGY

The word Energy is derived from the Greek term Energia, which means Capacity to do Work. Energy is the ability to make things happen. It is the most universal measure of all kinds of work by human and nature. Energy, exists in various forms, viz., mechanical energy, thermal energy, electrical energy, chemical energy, nuclear energy, etc.:

 

2. SOURCES OF ENERGY - CONVENTIONAL AND NON-CONVENTIONAL

The basic Energy Sources for generating electric power are Fossil Fuels, Hydel Source and Nuclear Fuel. These sources are known as Conventional Sources of Energy, as these sources are used over several decades for power generation. In the case of Hydro electric power, generation of power is at the mercy of the Nature. The other two resources, viz., Fossil Fuels for Thermal Power Plant and Nuclear Fuel are exhaustible sooner or later.

These problems prompted the engineers to look for Non-conventional Sources of Energy, namely, Solar Energy, Wind Energy, Tidal Energy, Geo-thermal Energy, Ocean Thermal Energy, Bio-Energy, etc.

Non-conventional sources of energy are also termed as Alternative Sources of Energy or Renewable Sources of Energy.

 

3. SOURCES OF ENERGY - RENEWABLE AND NON-RENEWABLE

The recent trend of classifying the sources of energy is as given below:

• Renewable Sources of Energy

Renewable Source of Energy is defined as the energy resource which is produced continuously in nature. It is neither consumed nor converted into something else. Therefore, it is inexhaustible. Examples: Hydel Energy, Solar Energy, Wind Energy, Tidal Energy, Geo-thermal Energy, Ocean Thermal Energy and Energy from Bio-mass.

• Non-renewable Sources of Energy

Non-renewable source of energy is defined as the energy resource which has been accumulated over the ages and is exhaustible. Examples: Fossil Fuels (Solid fuel: Coal; Liquid fuel: Petroleum products; Gaseous fuel: Natural gas) and Nuclear Fuel.

 

4. RENEWABLE SOURCES OF ENERGY

1. Hydro Energy (Energy Stored in Water)

Hydro Energy is an indirect source of Solar Energy. Water from Earth's surface evaporates by solar heat. It is transported by winds. This, in turn, results in rain fall. This cycle is going on since ages. The rain water flows as rivers. It is stored in dams.

Potential energy of water stored at a height is converted into mechanical energy in water turbines. This mechanical energy is converted into electrical energy by a generator.

Apart from being perennial and inexhaustible source of energy, it represents the cheapest source of energy in our country. Water is renewable source of energy, as it is neither consumed nor converted into something else.

2. Solar Energy (Energy from the Sun - Heat Energy)

Sun is a sphere of continuously generating heat energy. It radiates energy into space. The intensity of solar radiation at any point on the Earth's surface depends on various factors such as time of the day, the season, the latitude, the extent of cloud cover and the height above sea level.

The heat energy contained in the rays of sun is utilized to boil water and generate steam. This steam is used to drive the prime mover (steam turbine) to generate electrical power.

3. Wind Energy (Kinetic Energy)

Wind Energy is the kinetic energy contained in the force of winds. Wind energy can be made use of where wind at suitable velocity is available.

4. Tidal or Wave Energy (Kinetic Energy)

Ocean waves and tides contain large amount of potential energy. This potential energy of water is converted into mechanical energy by water turbines. This mechanical energy is used for power generation.

5. Geo-thermal Energy (Energy from the Earth's Core - Heat Energy)

Do you know what it is like near the center of the Earth? It is immensely hot at a temperature range of 4000°C to 10000°C. Geo-thermal energy is the thermal (heat) energy naturally available in the form of steam in some part of the earth below the Earth's surface. Generally geo-thermal steam is available in volcanic regions.

6. Ocean Thermal Energy

Solar energy incident on the Earth's surface is absorbed by the land as well as by the surface water of oceans. Oceans comprise about 75% of the Earth's surface. Therefore, the solar energy absorbed and stored as heat by oceans represents a very large potential source of energy. The temperature difference between the hot surface water and the cooler deep water of the ocean is used to generate electricity.

7. Energy from Bio-mass (Gobar Gas)

Bio-mass is an organic matter produced by plants, animal manure, cow dung, etc. Bacteria: acts upon such organic materials in the absence of air to produce bio-gas.

 

5. NON-RENEWABLE SOURCES OF ENERGY

1. Fossil Fuels

Fossil Fuels are energy rich substances formed from long-buried plants and micro-organisms. These are classified as Solid, Liquid and Gaseous and as Natural or Prepared. Solid Fuels: Naturally occurring solid fuels include wood varieties of coals viz., Anthracite, Bituminous and Lignite (brown coal), while prepared ones include Coke, Charcoal, etc. Liquid Fuels: Liquid fuels include Petroleum and its derivative, namely, Diesel oil. Gaseous Fuels: Naturally occurring gaseous fuel is Natural gas which comes out of gas wells and petroleum wells. Producer gas, Coal gas and Blast furnace gas are prepared gaseous fuels.

2. Nuclear Energy

Enormous release of energy from a small mass of nuclear fuel like Uranium makes this source of energy of great interest. The energy liberated by Nuclear Fission of one kg of U²³⁵ is equal to the heat energy obtained by burning 4500 tonnes of high-grade coal.

 

6. COMPARISON OF SOURCES OF ENERGY

1. Solid Fuels Vs Liquid Fuels

Solid fuels produce large quantity of ash after burning. Liquid fuels leave no or very little ash after burning. Liquid fuels require less storage space. But they are costly as compared to solid fuels. Further they require special type of burners for their burning. Also there is danger of explosion in the case of liquid fuels.

2. Solid Fuels Vs Gaseous Fuels

Gaseous fuels do not produce ash. Also greater cleanliness is assured as smoke is practically nil. Handling of gaseous fuels is not required as they can be easily piped into the furnace. However there is danger of explosion for gaseous fuels.

3. Availability of Sources of Energy

The thermal power plants depend upon coal which is exhaustible. For a hydropower plant, the availability of water depends upon the natural phenomenon of rain. Solar, wind and tidal energies are inexhaustible.

4. Capacity of Power Plant

The capacity of power production of steam or hydropower plant may be high. Diesel power plants are of limited generation capacity.

5. Air Pollution and Radiation Hazard

In thermal power plants, there is nuisance of smoke and air pollution. In nuclear power plants, radioactive waste is a health-hazard. Hydropower plant has no such air pollution or waste disposal problem.

6. Capital Cost and Operating Cost

Capital Cost of a thermal plant is less than a hydro-power plant. However, Operating Cost of a thermal power plant is higher than that of a hydropower plant. Capital Cost of a nuclear power plant is the highest whereas its running cost is perhaps least of all.

7. Location of Power Plant

Thermal plant can be located at the load center whereas a hydropower plant has to be located where water is available in large quantities. The nuclear power plants are best suited for areas far remote from coal reserves and water power.

 

7. RENEWABLE ENERGY RESOURCES

Advantages

1. Non-Exhaustible: Renewable energy resources are non-exhaustible.

2. Cost of Electricity: Hydroelectric power is the best developed, providing 8% of the world's energy supply in the form of very cheap electricity (1/8 and 1/2 of the cost of fossil fuel and nuclear generated electricity).

3. Pollution Free and Non-Hazardous: Renewable resources such as solar, wind and tidal energy are pollution free and non-hazardous compared to fossil and nuclear fuels which cause pollution or radio-activity. Bio-mass energy source is an exception.

4. Availability: Solar energy, wind energy, tidal energy, etc., are widely available.

5. Location and Transmission Cost: Renewable energy systems can be built close to the site, where the energy is required. This will minimize the transmission cost.

Disadvantages

1. Storing Energy: Our inability to store large quantities of energy using renewable sources either in the form of heat or as electricity.

2. Dilute Nature: The dilute nature of renewable resources means that large area of land or ocean is necessary to accommodate solar collectors. 30 km square for a solar power station or 1000 wind mills with 90 m blades set 250 m apart is required to replace the nuclear power plant on a 1 square km site.

3. Intermittent Nature of Availability: The intermittent nature of availability of the energy from energy sources like solar, wind, tidal, etc., is a major setback for the continuous supply of energy.

4. Cost-Effective Technology: The cost-effective, state-of-art technologies in harnessing renewable energy sources to generate very high power output is not yet fully developed.

Examples: Solar power plant, wind mill, etc.

5. Limitations of solar energy are: the problem of weather conditions, non-availability at night times and high initial investment.

6. Limitations of wind energy are: noisy operation, unsteady wind velocity resulting in varying power production, less power to weight ratio.

7. Limitations of tidal energy are: high initial cost, long power transmission distances and non continuous generation of power.