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Renewable energy or Green Power: What is it, its types and sources

By on April 22, 2016

Energy is a very important aspect of today’s life. And electrical energy is something which is required almost everywhere irrespective of the domain of work in consideration. Being such an important entity, it goes without saying that it’s demand is sky-rocketing. So it puts a lot of pressure on the energy resources available to us.

What is renewable energy?

There are basically two types of Energy:

1. Renewable Energy (or Green power or Green energy)
2. Non Renewable Energy

In this article, we shall try to understand about the renewable energy in detail.

As the name suggests, it is simply an energy which can be renewed. That’s putting it in the simplest of terms. To sound slightly more technical, renewable energy is defined as the energy which is produced from the resources that are continuously and invariably replenished by the nature without any influence of humans whatsoever.

In other words, it can be said that they do not run out..ever. That’s what makes them very important. They can be renewed and re-used.

But it should not be confused with alternate energy. Alternate energy is produced from the sources which can be suitably replace the exhaustible sources of energy available to us. In contrast to renewable energy, alternate energy has a broader pool of sources.

Sources of renewable energy

There are a few sources of renewable energy. Here is a list of these resources:

Wind power

What is wind power? Wind is produced when the atmosphere is heated up by the sun-rays in an uneven manner, rotation of earth on its axis and irregularities of the surface of earth. And wind is everywhere. So it presents a tremendous opportunity to harness the wind power. Wind power can be harnessed by using wind mills and wind farms. A wind mill is fitted with a wind turbine. The wind turbine spins when wind falls on it which in turn powers up a generator which finally produces current. It can be understood by taking the example of a fan. A fan runs on electricity and produces wind, the case of wind energy, it’s just the opposite. Here, wind produces electricity through a certain process.

Solar power (sun power)

Sun is the centre of our solar system. It radiates a lot of energy in the form of its rays. This energy can also be harnessed by using different methods. It is a tremendous source of sustainable energy. And yes, it is limitless abundant. Solar energy can be converted to electrical energy by using solar panels or solar cells. There are many advantages associated with solar energy. The tools which convert solar energy to electrical energy, like solar panels, are not under the constant threat of some mechanical failure or malfunction. The conversion is a fairly simple process and does not require bulky apparatuses. They require little maintenance. They do not produce any sound while in operation and thus cause little inconvenience in that regard .

The most evident disadvantage of solar energy is that they cannot be used when there is an absence of sunlight. So at nights, they are rendered useless. Also, during monsoons when there is a thick cover over the sun, solar power is difficult to harness. Also, the output is maximum when the panel is at a particular angle with the sun which means should be directly facing the sun. But it might not always be possible due to the way in which the building (where one is interested to install a solar panel) is constructed. The maximum efficiency reaches up to 20%, which is not too big a number. Although with the technical advancements, it is being improved.


Biofuel, the word can be divided in two words bio and fuel. ‘Bio’ which means ‘related to life’. So this is a kind of renewable source of energy which is produced wholly (or partially) from the living beings. Also it can be harnessed from the waste produced by the living things  To produce electricity, fuel has to be burnt. And when fuel is burnt, it produces many undesirable gases due to combustion, carbon dioxide is one of them. The excess of carbon dioxide in the atmosphere has always been a major cause of worry for the whole world. So there is a vast demand of a kind of energy source which is sustainable and efficient, and at the same time, is environment friendly. Biofuel does just that. As biofuels can be made from a variety of sources, that is why they are divided in different generations :

1st generation – Produced from oil, starch or animal fat.

2nd generation – Produced from agriculture (non food crops or waste)

3rd generation – Produced from algae

4th generation – These are produced by some specific plants which are specifically engineered.

Geothermal energy

Geothermal energy or geothermal power is the power which is harnessed from the surface of the earth. The word ‘geothermal’ is formed by using two words; geo which means ‘related to earth’ and ‘thermal’ is related to heat. The earth is formed by three layers; crust which is the uppermost part, mantle which is the part which is below the crust and the core, which below the mantle. The core is a double layered part which is made by molten iron which encompasses a solid iron centre. This is the hottest section of the earth. So the heat energy which is closest to the surface of earth with the help of rain water produces geothermal heat.

One might wonder how one can identify geothermal energy visually? There are some phenomena like volcanoes or hot springs. There are various methods which are deployed to locate the sources of the geothermal energy which is known to scientists.

Hydro Power

Hydro power (or power from water) is also a very important source of electricity. It is, in fact the most widely used renewable source of energy throughout the world. Hydro power, as the name suggests, is produced by water. It basically consists of a dam and a water reservoir. The water is released from the dam at very high velocity which when falls on a turbine makes it rotate which in turn produces electricity.

Hydro power has many advantages. No fuel is burnt, so there is minimal pollution. Not only this, but hydro power plays a major role in reducing the greenhouse gas emissions. Water can be stored using big reservoirs by rain water harvesting. The operations and maintenance costs are also small.

However it also has a few drawbacks. The investment costs to build a hydro-electric power plant is very high. Since a plant is huge, it eats up a lot of land space and displaces large communities of people living in the neighbouring areas which sometimes leads to a lot of dis-satisfaction amongst people. It also affects the land and wildlife habitats.

Fuel Cells

Fuel cells are a coming of age source of renewable energy. In the most basic of terms, fuel cells produce electrical energy by the means of a chemical reaction. The chemical reaction occurs between the two elements on the electrode in the presence of a liquid solvent called as electrolyte. When the reaction occurs, electrical energy is produced which can be used outside the cell. Hydrogen is the most commonly used element which facilitates reaction in the fuel cell. Hydrogen is the simplest element having only one proton. It is also the most abundant element in the universe. But interestingly, it does not occur (abundantly) as a separate gas. It is a chief chemical component of many things around us like water.


As there is a huge demand of electricity and a very limited number of sources available to us, it is in the best interest of everyone that we should encourage the usage of the renewable sources of energy. This will not only control the rate at which the natural resources are getting consumed, but also it will provide us with a different and viable option for fulfilling our needs




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