What is Hydrogen energy?

Energy is a quantity that cannot be defined, its existence can only be felt. In simple language, if a system possesses energy, it can do a specific kind of work. There are many forms of energy sources which people can use to obtain work. Solar energy, tidal energy, hydroelectric energy, geothermal energy, wind energy are some of the renewable energy sources which are primarily used for the production of electricity.

Other sources of energy, like Hydrogen energy, are rather a recently developed renewable energy source. Hydrogen is a gas with atomic number one. It is the lightest gas in the periodic table. Hydrogen is a colorless, odorless, zero-emission, highly combustible gas, which is often referred to as a cleaner fuel. Energy from Hydrogen is utilized in the form of fuel cells, preferably known as Hydrogen fuel cells for storing and generating electricity. Because of its low carbon content, Hydrogen is aggressively regarded as "Blue Hydrogen".

The on-pandemic of the novel coronavirus disease 2019 (COVID-19), has made the global economy undergo a downfall, especially in the fuel sector. As such, the Hydrogen Council, a global CEO level advisory council caters to improve and develop the Hydrogen economy, regarding Hydrogen fuel cell sectors.

Occurrence of Hydrogen

Hydrogen gas is considered the most abundant element found in the earth's atmosphere. It readily occurs as a major constituent element of water. Besides this, hydrogen forms the basic composition of petroleum products, minerals, cellulose, starch, alcohols, acids, sugar, fats, etc. At standard temperature and pressure (STP) hydrogen occurs as a diatomic molecule bearing the molecular formula H2. In nature, hydrogen has three isotopes, protium, deuterium, and tritium, all these isotopes have chemical properties but their atomic masses differ. 

Hydrogen extraction methods

Hydrogen primarily exists as a combination of two or more elements in the earth. To obtain pure hydrogen, it should be separated. There are various processes available to do that. Some of them are outlined below.

Natural gas reforming

The process begins with reacting natural gas with high-temperature steam, which gives rise to synthesis gas. Natural gas is a hydrocarbon gas primarily composed of methane and other higher alkanes. Natural gas reserves are deep inside the earth's surface near the beds to crude oil.

Synthesis gas is a mixture of hydrogen, carbon monoxide with small percentages of carbon dioxide. The carbon monoxide thus obtained is made to react with water to obtain additional hydrogen.


Electrolysis is a water-splitting process that decomposes water molecules into their constituents elements, hydrogen, and oxygen. The process is carried out in a suitable apparatus with electrodes dipped in water. When electricity is passed through an anode, hydrogen appears at the cathode, and oxygen appears at the anode. If the electricity used in the process is obtained from a renewable source, the hydrogen so obtained can be considered as a renewable energy source as well.


In this process, micro-organisms such as bacteria and fungi break down organic substances such as sugars, bio-mass, corn Stover, etc., to produce hydrogen gas. The fermentation process often occurs without light hence it is also termed the dark fermentation process.

Hydrogen fuel cell

Fuel cells are renewable power sources, and a class of electrochemical cells, where conversion of chemical energy of a suitable fuel to electrical energy takes place. This energy conversion follows redox reactions.

In a hydrogen fuel cell, the chemical energy of the hydrogen is used to produce electrical energy with heat and water as the by-products of the chemical reaction. Hydrogen fuel cells function like batteries, where energy transition takes place, but they don't get exhausted over time nor do they need recharging. A typical hydrogen fuel cell consists of two electrodes known as a cathode (positive electrode) and anode (negative electrode). A suitable electrolyte is filled between these two electrodes. Hydrogen gas is passed through the anode and pure air is passed through the cathode. In presence of a catalyst, hydrogen decomposes into protons and electrons which are made available at the cathode. Electrons flow through the external circuitry while the protons move into the electrolyte and combine with oxygen to form heat and water.

Working principle of hydrogen fuel cell
CC BY-SA 3.0 | Image Credits: https://en.wikipedia.org | Paulsmith99

Uses of Hydrogen fuel cells

Sooner or later, the world will use hydrogen as a power source for all of its major applications. Due to its net-zero emission of harmful gases and pollutants, it would be a much-preferred source of energy for automobiles and aerospace applications. Hydrogen-powered electronic appliances, gadgets, and batteries are sooner to replace conventional power sources.

Warehouse logistics

When it comes to large warehouses, the number of equipment such as lift trucks, carriers, etc., are also large, in such cases use of conventional sources of energy like petroleum products to fuel them is uneconomical. Switching to cleaner and easily available fuel like hydrogen is a boon.

Internal combustion engines

Sooner the traditional internal combustion engines that use petrol and diesel would be replaced by hydrogen-powered engines. These hydrogen-based engines would form the primary component of all fuel cell vehicles.

Unmanned Aerial Vehicles (UAV)

Almost all the UAVs currently used operated with conventional batteries that have limited power, which ultimately limits the functionalities of the UAVs. Switching to a hydrogen fuel cell-powered source would boost up the power storage capacity to three times.

Context and Applications

The topic finds its existence in various undergraduate and postgraduate degree courses like-

  • Bachelors in Technology (Mechanical Engineering)
  • Masters in Technology (Mechanical Engineering)
  • Bachelors in Science (Physics)
  • Bachelors in Science (Chemistry)

Practice Problems

1. Which of the following method uses electrodes to produce hydrogen?

  1. Reforming
  2. Electrolysis
  3. Fermentation
  4. All of these

Correct option- b

Explanation: By the method of electrolysis, water is decomposed into hydrogen and oxygen. The apparatus uses two electrodes dipped into the water. Upon passing electricity, hydrogen appears at one of the electrodes.

2. Which of the following is true for a hydrogen fuel cell?

  1. It uses a suitable electrolyte.
  2. It has two electrodes.
  3. It uses a suitable catalyst to initiate the chemical reaction.
  4. All of these

Correct option- d

Explanation: A hydrogen fuel cell uses a cathode and an anode placed in a suitable electrolyte. In the presence of a catalyst, the reactions initiate to produce electrons and protons.

3. For which of the following reasons, hydrogen is termed as a blue fuel?

  1. It has zero emission.
  2. It is a clean fuel.
  3. It is a renewable energy source.
  4. It has a low carbon content.

Correct option- d

Explanation: Because of low carbon content, hydrogen is often termed as a blue fuel.

4. Which of the following is true for natural gas?

  1. It is composed of hydrocarbons.
  2. It has higher alkane composition.
  3. Both a and b
  4. It is primarily composed of ethane.

Correct option- c

Explanation: Natural gas is a hydrocarbon-based gas primarily composed of higher alkanes and methane.

5. Which of the following is the correct method of producing synthesis gas?

  1. Reacting natural gas with saturated steam
  2. Reacting natural gas with high-temperature steam
  3. Reacting natural gas with low-temperature steam
  4. Reacting natural gas with water vapor

Correct option- b

Explanation: Synthesis gas is produced by reacting natural gas with high-temperature steam.

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