Question

Write short notes on:
1. Geothermal energy
2. Wind energy
3. Tidal energy
4. Biogas

Answer 1

Dear Student

1. Geothermal energy is the heat energy in the Earth’s interiors. The temperature at the centre of the Earth is about 6000°C. In some areas, molten rock (magma) is found very close to the surface of the Earth. This hot rock meets underground water and heats it up. This produces steam. Such a place is known as a hot spot . Sometimes, this heated underground water finds an outlet through which it comes out on the surface of the Earth. Such outlets are known as hot springs .
When there are geological changes, the molten rocks present in the core of the earth are pushed to the earth’s crust. This forms regions of hot spot. Steam is generated when the underground water comes in contact with these hot spots forming hots prings. This trapped steam is used to generate electricity in the geothermal power plants.

2.

Wind can be used as a reliable, clean source of renewable energy. Wind energy has been used by people for thousands of years. Today, wind energy is mainly used to generate electricity using wind turbines.

Generating electricity from wind has many advantages. Wind energy:

• is clean and does not produce greenhouse gases
• is low cost once the turbines are installed

Wind energy is energy collected from motion caused by heavy winds. Wind energy is collected in turbines with propellers that spin when the wind blows and turn the motion of the propeller into energy that can be used in the electrical grid. Wind energy is a clean, renewable energy source that is abundant in windy areas. Large wind farms are often located outside of cities, supplying power for electrical grids within the city.

3. Tidal energy is produced by the surge of ocean waters during the rise and fall of tides. Tidal energy is a renewable source of energy. During the 20th century, engineers developed ways to use tidal movement to generate electricity in areas where there is a significant tidal range—the difference in area between high tide and low tide. All methods use special generators to convert tidal energy into electricity.Tidal energy production is still in its infancy. The amount of power produced so far has been small. There are currently two commercial-sized tidal power plants operating in the world. One is located in La Rance, France; the other is in Annapolis Royal, Nova Scotia, Canada. There is a third experimental plant operating in Kislaya Guba, Russia. The United States has no tidal plants and only a few sites where tidal energy could be produced at a reasonable price. France, England, Canada, and Russia have much more potential to use this type of energy.In the United States, there are legal concerns about underwater land ownership and environmental impact. Investors are not enthusiastic about tidal energy because there is not a strong guarantee that it will make money or benefit consumers. Engineers are working to improve the technology of tidal energy generators to increase the amount of energy they produce, to decrease their impact on the environment, and to find a way to earn a profit for energy companies.

4. Biogas is a mixture of gases (containing predominantly methane) produced by the microbial activity and which may be used as fuel.
Production of biogas takes place in a biogas plant.
The biogas plant consists of a concrete tank (10-15 feet deep) in which bio-wastes are collected and a slurry of dung is fed. A floating cover is placed over the slurry, which keeps on rising as the gas is produced in the tank due to the microbial activity. The biogas plant has an outlet, which is connected to a pipe to supply biogas to nearby houses. The spent slurry is removed through another outlet and may be used as fertilizer.
Uses of Biogas: for cooking and lighting and slurry used as fertilizer

Regards