## Wind and Bio-mass Energy

Subject: Physics

#### Overview

Biogas is a mixture of various gases formed when the animal dung is mixed with water and ferment in the absence of air. A device used to convert wind energy into the mechanical energy of the machine is called windmill. This note provides us with an information on the wind and bio-mass energy.

### Wind Energy

The wind possesses kinetic energy. The kinetic energy of the wind is known as wind energy.

#### Uses of Wind Energy

The kinetic energy of the wind can be used to

1. move the sail boats in lakes, rivers and seas.
2. operate water pumps to draw underground water.
3. run the flour mills to grind the grains.
4. produce electricity.

A device used to convert wind energy into the mechanical energy of the machine is called windmill.

##### Construction

It consists of a wheel rotates about an axle mounted on a pole. The wind energy is used to rotate the wheel about its axis.

Uses

1. The windmill to operate a water pump
2. The windmill for producing electricity
##### Windmill to operate a water pump

The axle of the windmill is connected to a crank rod. The free end of the water pump rod or piston is connected to U-bend of the crank rod.

Working: When the wind strikes the blades of the windmill, the kinetic energy of the wind is used to rotate the wheel of the windmill. As a result, the axle or shaft attached to the wheel rotates which turns the crank rod. The u-bend of the crank rod produces up and down motion of the piston of the water pump. Hence, the underground water is drawn to the surface of the earth.

##### Windmill for producing electricity (wind generator)

When the armature of a generator rotates between two poles of the strong magnet, then electricity is produced. Windmill rotates when the wind falls on the wheel of a windmill. So the armature of the generators rotates between two poles of a magnet along with the rotation of the wheel of the wind. Electric current is produced. This is how, the kinetic energy of the wind is converted into electric energy.

1. Wind energy produces no smoke and no harmful gases.
2. Wind energy is free and running it is also very economical.
3. The source of wind energy is unlimited.

### Bio-mass energy

During photosynthesis process, solar energy is converted into chemical energy. So, plants have stored chemical energy in the forms of biomass. The matter contained in the body of different plants and animal have biomass. The gas obtained from biomass is called biogas.

1. It is a renewable source of energy.
2. It’s production is very economical.
1. Due to the release of smoke, it causes air pollution.
2. A large amount of energy cannot be produced by biomass.
##### Application
1. The biomass energy can be used in the home for heating and cooling purposes.
2. It can be used for heating food in food industries.
3. The biogas like gobar gas can be used for lightening purposes.

#### Gobar gas or Bio Gas

Biogas is a mixture of various gases formed when the animal dung is mixed with water and ferment in the absence of air.

##### Biogas Plant

The arrangement of producing biogas from animal dung, human excreta, industrial and domestic wastes is known as biogas plant. The arrangement of producing biogas from animal dung, human excreta, industrial and domestic wastes is known as biogas plant. A biogas plant consists of a well shaped, underground tank T called digester, which is made of bricks, and has a dome-shaped roof D. The digester is a kind of sealed tank in which there is no oxygen which acts as a gas-holder for the biogas. On the left side of the digester tank is sloping inlet chamber I and on the right side is a rectangular outlet chamber O, both made of bricks. The inlet chamber is for introducing fresh dung slurry into the main digester tank whereas outlet chamber is for taking out the spent dung slurry after the extraction of biogas. The inlet chamber is connected to a mixing tank M while outlet chamber is connected to the overflow of tank F. There is a gas out let S at the top of the dome having a value V.

Working

Cow-dung and water are mixed in equal proportions in the mixing tank M to prepare the slurry. This slurry of dung and water is fed into the digester tank T through the inlet chamber I. the digester tank is filled with dung slurry up to cylindrical level, the dome being left free for the collection of biogas. It might take 50 to 60 days for the new-gas plant to become operative. Gradually when the biogas starts collecting in the dome, it exerts pressure on the slurry in the digester tank and forces the spent slurry to go into overflow tank F, through the outlet chamber O. the spent slurry is gradually removed by the overflow of the tank. The spent dung slurry left after the extraction of biogas is rich in iron and phosphorous compounds and forms good manure.

1. Biogas is used for cooking food and heating water.
2. Biogas does not produce smoke during and hence there is no air pollution.
3. It is the cheapest source of energy.

Reference

Manu Kumar Khatry, Manoj Kumar Thapa, et al.Principle of Physics. Kathmandu: Ayam publication PVT LTD, 2010.

S.K. Gautam, J.M. Pradhan. A text Book of Physics. Kathmandu: Surya Publication, 2003.

##### Things to remember

The kinetic energy of the wind is known as wind energy.

A device used to convert wind energy into the mechanical energy of the machine is called windmill.

Biogas is a mixture of various gases formed when the animal dung is mixed with water and ferment in the absence of air.

The arrangement of producing biogas from animal dung, human excreta, industrial and domestic wastes is known as biogas plant.

• It includes every relationship which established among the people.
• There can be more than one community in a society. Community smaller than society.
• It is a network of social relationships which cannot see or touched.
• common interests and common objectives are not necessary for society.