What is an energy source?

An energy source refers to the various sources, whether natural or artificial, which are primarily used for the generation of electricity by power plants. Production of electricity by power plants demands the consumption of energy sources in large quantities, which cannot be fulfilled by traditional sources, such as coal and wood. Also, the mere usage of such sources leads to their depletion at a much faster rate.

The primary principle of a power plant is the conversion of the energy sources, which are supplied as input, to heat energy. The heat energy thus produced is either used to produce high-pressure steam, which runs a steam turbine or used to run a gas turbine by the pressure gases of combustion. A generator is usually coupled to these turbines that convert the energy of combustion into electrical energy.

Here, in this article, a brief outline of different energy sources is discussed.

Types of energy sources

There are two kinds of energy sources known to mankind, conventional or nonrenewable energy sources and non-conventional or renewable energy sources.

Nonrenewable energy sources

Nonrenewable energy sources are those energy sources that get exhausted upon usage with time and are not easily available. It takes a series of operations and processes to extract the fuel and its by-products that produce energy when burnt. These energy sources cannot be recharged at a faster pace if consumed rapidly. The reserves of such energy sources take billions of years to form and are mostly available beneath the earth's surface. These energy sources are formed when dead remains of plants and animals get buried deep inside the earth's surface and are subjected to high pressures and temperatures. Long-term and over-exploitation of such energy sources on a large scale have led to changes in the ecosystem with a major impact on climate change. Some of the examples of this category of energy sources include natural gas, fossil fuels, petroleum, coal, and nuclear energy. Out of which, two-thirds of the world's population relies on energy supply by petroleum by-products.

Renewable energy sources

Renewable energy sources are those energy sources that are present in ample amounts and are readily available. These energy sources are low-carbon emitters and account for zero-emission of greenhouse gas. These energy sources are eco-friendly and do not harm the environment. The majority of power plants have shifted their fuel sources towards renewable energy sources in energy production as a courtesy towards the environment and to safeguard it

Renewable energy resources are also known as flow resources. They replenish at a faster pace even if the consumption exceeds the threshold limits of consumption. Special equipment and machinery are employed in power plants to convert the energy associated with these sources into electrical energy. Biomass energy, hydropower energy, solar energy, wind energy, geothermal energy, and tidal energy are some of the examples of renewable energy sources.

Types of nonrenewable energy sources

Here, in this section, a brief outline has been provided about the different energy sources that fall under the category of nonrenewable energy sources.

Fossil fuels

Fossil fuels are the fuels that are formed by decomposing the remains of plants and animals. These fuels are found beneath the earth's crust and are primarily composed of carbon and hydrogen. Coal, petroleum, and natural gas are the main by-products of fossil fuels. Coal is a fossil fuel that occurs between the sedimentary rocks piled up in layers. Coalfields are set up at various locations that dig and extract out the coal required by many coal-fired power plants. Natural gas occurs at the voids or pockets formed between the sedimentary rocks. Natural gas is primarily used for cooking purposes and is sometimes used as fuel to power automobiles. Another major category of fossil fuel that accounts for the majority of power sources in automobiles worldwide is petroleum. Petroleum is a fossil fuel that occurs beneath the earth's crust in the form of liquid or solid. According to reports, 84% of the world's energy needs are fulfilled by fossil fuels with 15 billion metric tons of fossil fuels are consumed globally.

Nuclear energy

Nuclear energy makes use of nuclear fuel like uranium 235, deuterium, polonium, plutonium 238 for the production of energy. These sources are highly energy-efficient and account for high thermal energy efficiency. There are generally two kinds of nuclear processes which are used to produce energy, they are nuclear fission and nuclear fusion. The fuels in this case are fed in into a nuclear reactor which initiates a nuclear reaction. The heat from the reaction is used to drive a steam turbine or a gas turbine which produces electricity by a generator.

Types of renewable energy sources

In this section, the various renewable energy sources are outlined. The prime advantage of using such energy is that they are non-polluting and nature friendly.

Biomass energy

Biomass is an organic material either of plants or of animals, which is used in the generation of electricity. Woods, crops, manure, animal wastes, and some garbage from the biomass. These materials are the major input to a biomass plant, that burns these sources to produce heat energy. The energy from heat is transferred to turbine and generator which generate electricity.

Geothermal energy

Geothermal energy refers to the heat energy which is found beneath the earth's surface. Magma and lava are the main cause of geothermal energy. The heat from these sources heats and boils the water which is present underground, The boiling water produces high-pressure steam which can be used to drive a turbine and generator.

Hydropower energy

Hydropower energy refers to the energy that can be acquired from running water. In a typical hydropower plant, the kinetic energy of flowing water is used to turn a hydraulic turbine which in turn rotates an AC generator.

Solar energy

Solar energy refers to the energy that can be obtained from the sun. Solar power plants employ several solar cells, which store the sun's energy into electrical energy due to a chemical reaction. This electrical energy is transferred to electricity grids, which can be consumed by households.

Context and Applications

This topic is majorly taught in different undergraduate and postgraduate degree courses of:

• Bachelors in Technology (Mechanical engineering, Civil engineering)
• Masters in Technology (Mechanical engineering, Civil engineering)
• Masters in Science in Energy sources

Practice Problems

Q 1. Which of the following is a renewable energy source?

a. Solar energy

b. Fossil fuel

c. Coal

d. Nuclear energy

Answer: Option a

Explanation: Solar energy is an example of a renewable energy source.

Q 2. Which of the following fuels is used by nuclear power plants?

a. Uranium 235

b. Fossil fuel

c. Plutonium 238

d. Both a and c

Answer: Option d

Explanation: Uranium 235 and plutonium 238 are the fuels that are used by nuclear power plants.

Q 3. Which of the following is a conventional energy source?

a. Petroleum

b. Solar energy

c, Hydropower energy

d. Wind energy

Answer: Option a

Explanation: Petroleum is a conventional energy source.

Q 4. In which of the following arrangement, a nuclear reaction is carried out?

a. National renewable energy laboratory (NREL)

b. Nuclear reactor

c. Nuclear cells

d. Nuclear laboratory

Answer: Option b

Explanation: The nuclear reaction is initiated in the nuclear reactor.

Q 5. Where are fossil fuels found?

a. Deep inside the ocean

b. Beneath the earth's crust

c. Both a and b

d. None of these

Answer: Option b

Explanation: Fossil fuels are found beneath the earth's crust.