[Physics Class Notes] on Renewable Energy Pdf for Exam

Renewable energy, as the name suggests is an energy that can be renewed or replenished. It is often referred to as ‘clean energy’ because it is less harmful to the environment as compared to non-renewable energy. Renewable energy is obtained from natural resources and processes that are constantly replenished.

Whenever a question arises about what is renewable energy, we can simply say that it is the energy obtained from the resources which constantly renew themselves, hence it is available in sufficient amounts for our use such that it would not finish no matter how much we use it. Sunlight and wind energy can be taken as an example. These resources keep flourishing even if their availability is dependent on time and weather respectively.

Renewable Energy Definition

It is the type of energy obtained from the resources which do not deplete or replenish themselves within a human’s lifetime. It is opposite to the energy obtained from depleting fossil fuels.

Renewable Energy Resources

These are those resources that produce renewable energy. They are mostly present in nature. To the question ‘what are renewable energy sources’, we can say that a renewable source is a natural resource that either through natural reproduction or other recurring processes replenishes the depleted or consumed amount of resource within a finite time interval on the human time scale. Solar, wind, biomass, geothermal, and water (hydro) are major renewable resources.

Types of Renewable Energy

Here are some major renewable energy examples.

1. Solar Energy

Solar energy is the energy obtained from the sun. The radiant light and heat energy are harnessed by solar collectors. The sun’s energy can be captured to generate electricity or heat through a system of panels or mirrors.

Solar or photovoltaic cells convert sunlight directly into electricity while solar thermal collectors use heat-absorbing panels and a series of attached circulation tubes to heat water or buildings.

2. Wind Energy

Wind power or wind energy makes the use of wind to provide mechanical power to electric generators through wind turbines so that they can do operations like milling or pumping. The wind hits two or more propeller-like blades around a rotor. This rotor is connected to the main shaft connected to the generator so that when the rotor moves it moves the shaft in turn, hence electricity is produced as the generator operates. These turbines are installed mostly in high-altitude areas.

3. Geothermal Energy

Earth has its thermal energy stored in it. The energy that is generated from the thermal energy stored in the earth is called geothermal energy. Hot springs and volcanoes are used to capture the heat energy and this heat is directly used by industries for heating the water and other purposes.

4. Hydropower

Hydropower or hydroelectricity is the energy generated by the use of water. Dams and reservoirs are constructed on flowing water which uses the kinetic energy of the water to run turbines and in turn, generate electricity. Hydropower is also generated by making use of tides known as tidal energy. Also, energy from the surface of ocean waves is used to produce electricity known as wave energy.

5. Bioenergy

Bioenergy is derived from biomass which is the organic waste of animals and plants. Biomass contains stored chemical energy. It is burnt to produce bioenergy. It may be converted to biofuel and then used or it can directly be used to produce heat through combustion. The heat generated from combustion is used to run generators to produce electricity.

Importance of Renewable Energy

The importance of renewable energy lies in the need for renewable energy over the conventional form of energy. Some important points are given below.

1. Renewable energy is a source of clean, inexhaustible energy.

2. It is pollution-free as it does not produce any greenhouse gas and polluting emissions which are otherwise produced in the case of non-renewable sources.

3. The costs for renewable energy are also falling at a sustainable rate opposite to the rate trend of fossil fuels.

4. It reduces energy dependence on fossil fuels.

5. It can be easily generated because renewable sources are mostly present all around, there is no non-availability issue.

6. Both economically and environmentally, renewable technologies are becoming competitive to conventional sources of energy.

Uses of Renewable Energy

1. The major use of all renewable energies is to generate electricity. In 2018, 26.2 percent of global electricity requirements were fulfilled by renewable energy which is expected to rise to 45 percent by 2040.

2. Solar energy can be directly used for heating and lighting homes, for hot water heating, solar cooling, etc.

3. Biomass is also used to heat buildings and provide heat in industries. It is also used as a fuel when converted to liquid biofuel.