Sources of Energy

01

EXAMPLE

Fossil Fuels

Fossil fuels are fuels formed by anaerobic decomposition of buried dead organisms over millions of years. A lot of fuels fall under this category like coal, petroleum and natural gas. They are presently the largest source of energy used on earth. They are exhaustible(limited in amount) and cause air pollution.

02

RESULT

Production of electricity

Some common methods used to produce electricity are:

1. Burning fuels (coal, petroleum, etc) in thermal power stations.
2. From wind energy in windmills.
3. From nuclear energy in atomic power plants.
4. From solar energy using solar panels.
5. From hydel energy in hydroelectric power stations.

03

DEFINITION

Renewable and non-renewable resources of energy

Renewable resources are resources that are replenished by the environment over relatively short periods of time. They are more desirable to use because they will have regenerated by the time we’ve used it up. Examples: Solar, wind, hydel and bioenergy.
Non-renewable resources are resources that are not easily replenished by the environment. Example: Fossil fuels and minerals.

04

DEFINITION

Differentiate between green and brown energy

Brown energy is the traditional type of electricity that is produced through the normal means. Typically, this refers to electric plants that produce power with coal or some other fossil fuels. It is referred to as brown energy because of the pollution that is caused by this form of energy.

Green energy is a form of power that is renewable and does not pollute the earth in any way. Some examples of green energy are solar power, hydroelectric power, wind power, geothermal power, and biodiesel.

05

RESULT

Disadvantages of hydro power plants

Some disadvantages of hydro power plants are:

• Dams can be constructed in only a limited number of places (hilly terrains).
• Large areas of agricultural lands and human habitat gets submerged.
• Flooding of forests leads to a large destruction of ecosystems.
• Vegetation submerged under water releases methane which contributes to greenhouse effect.

06

DEFINITION

Hydroenergy

Hydropower is the capture of the energy of moving water for some useful purpose.
There are many forms of water power:
1) Water wheels, used for hundreds of years to power mills and machinery
2) Hydroelectric energy, a term usually reserved for hydroelectric dams
3) Tidal energy, which captures energy from the tides in horizontal direction
4) Tidal stream power, which does the same, but vertically
5) Wave power, which uses the energy in waves

07

DEFINITION

Bioenergy and Wind energy

The dead parts of plants, animals and their wastes is called Biomass(example: cattle dung, wood, crop residues, etc) and energy stored in them is called Bioenergy. These fuels are used to produce biogas by anaerobic decomposition of biomass which is then used to produce electricity. The main content of biogas is methane(45-70%) and waste products are used as fertilizers.

Windmills are used to convert the kinetic energy  of  wind into desired form like lifting water, running flour mill and producing electricity. Wind farms are located at places where wind blows continuously and with good velocity.

08

DEFINITION

Non-conventional sources of energy

The sources of energy which are not used very commonly and are newly introduced are called non-conventional sources of energy. Some of the general characteristics of these sources are:

1. They are inexhaustible.
2. They do not cause pollution.
3. They are cheap to be maintained, stored and transmitted.

Examples include wind, tidal, solar, geothermal, and bioenergy.

09

DEFINITION

Conversion of wave energy to other forms of energy

Movement of large quantities of water up and down in the seas and oceans, in the form of waves is also a source of energy. This energy can be converted into mechanical energy and electrical energy. the tropical coastline of our country, especially the south west coast line, is found to be highly suitable for establishing energy conversion plants. However, the cost of energy conversion per unit, is very high, since it requires many special equipments to be created near the sea. Wave energy is however more reliable than wind energy since the uctuations are comparatively less pronounced.

10

EXAMPLE

Energy from sea

The energy potential from sea energy is large but its efficient commercial exploitation is difficult. The following types of energies can be harnessed from the sea:

• Ocean wave energy: Kinetic energy in the waves is used to generate electricity.
• Ocean thermal energy: The temperature difference at different depths of ocean is converted into mechanical and then into electrical energy.
• Tidal energy: The potential energy stored in the tides is used to harness electrical energy.

11

EXAMPLE

Nuclear Power Plant

Nuclear energy is produced by a process called nuclear fission in which the nucleus of a heavy atom (such as uranium, plutonium or thorium) when bombarded with low-energy neutrons can be split apart into lighter nuclei. When this is done, a tremendous amount of energy is released. In a nuclear reactor designed for electric power generation, such nuclear fuel can be part of a self sustaining fission chain reaction that releases energy at a controlled rate. The released energy can be used to produce steam and further generate electricity.
Energy EE released in a nuclear reaction is given by:
E=Δmc2E=Δmc2
c=3×108 m/sc=3×108 m/s
Preferred unit of energy is electron volts (eV): 1 eV=1.602×10−19 J1 eV=1.602×10−19 J
When Δm=1 amuΔm=1 amu, energy released is about 931 MeV931 MeV.

12

RESULT

Advantages and disadvantages of Nuclear Energy

Advantage of using nuclear energy is that it can be used for production of large amount of energies.

Disadvantages of using nuclear energy are:

• The excess radiations from these reactors are harmful to health and can affect many generations.
• Nuclear fuels can be misused to build destructive atomic bombs.
• Cost of installation of nuclear power plants is very high and needs to be done in remote areas for safety purposes.