What is hydrogen fuel cell and how does it produce electricity
Hydrogen is one of the simplest elements consisting of one electron and one proton. Moreover, it is most abundantly present in nature. However, it is not present in its gaseous form on the earth naturally. This simple element is always found combining with other elements and forms compounds like water H2O.
However, for the past few years, scientists have researched and found that hydrogen can be used as an alternative fuel – hydrogen fuel. Furthermore, its popularity is inclining drastically as this fuel is capable of producing a huge quantity of heat on combustion.
So, what is a hydrogen fuel cell? And what are hydrogen fuel cells used for? You can find all answer related to this fuel option in the following content.
What is Hydrogen Fuel?
First, you must understand what is hydrogen fuel. It is a zero-emission fuel which is produced burning of hydrogen with oxygen. Also, you might get astonished by the fact that this alternative fuel can release a greater amount of energy compared to petrol and diesel. More specifically, it is three times more efficient than petrol.
Furthermore, while burning, hydrogen fuel produces a lot of lesser pollutants than petrol or diesel. Nearly around 95% of hydrogen is formed by steam reforming of fossil fuels or by partial methane oxidation.
However, by coal gasification or water electrolysis, hydrogen can also be produced with zero carbon emission. Other than these processes, certain bacteria and algae also release hydrogen by utilising sunlight under specific conditions. Organic compounds, precisely the hydrocarbons that create several fuels like natural gas, gasoline, propane, and methanol, are also a large source of hydrogen fuel.
Hydrogen Fuel Cell
To know about hydrogen fuel cell, at first you should know what a fuel cell is.
A fuel cell is a mechanical device that can convert the energy captured within molecular bonds or chemical potential energy into electrical energy. Now, the proton exchange membrane of a hydrogen fuel cell uses hydrogen and oxygen as fuels. This PEM cell combines oxygen and hydrogen to create heat, electricity, and water.
The anode of this fuel cell carries hydrogen, and the cathode carries oxygen. Here, these hydrogen molecules divide into protons and electrons at the anode part of the cell. And due to the applications of hydrogen fuel cells, these two elements react, and these cells produce a huge amount of energy.
Thus, often, this fuel cell is compared to batteries. Both fuel cells and batteries produce energy via chemical reactions and transfer that energy into workable electric power.
Key Points
Hydrogen fuel carries nitrogen oxides or NO as pollutants. This is because hydrogen molecules treat nitrogen gas as one of the impurities.
By adding water to the cell container, this pollution can be further reduced. This process can prevent the reaction of nitrogen and oxygen.
As you know, hydrogen belongs to the first place in the periodic table as it is lighter than air. So, a fuel cylinder containing hydrogen can weigh much lesser than of petrol or diesel.
The temperature needs to be decreased at 20 K to keep hydrogen gas into a liquid state. However, due to the produced heat in reaction, this becomes quite difficult. Thus, it is affecting fuel efficiency. Now, scientists around the globe are researching to find out a way to use hydrogen fuel more simply.
So far, you have learnt some basic yet important information to answer what is a hydrogen fuel cell, and how does it work.
Quiz 1.0
What is the process used in a hydrogen fuel cell to generate electricity?
Options:
Fusion
Organic reaction
Combustion
Electrochemical reaction
What does fuel cell emit?
Options:
Carbon
Water
Oxygen
Hydrogen
How can you increase the electricity amount of a fuel cell mechanism creates?
Options:
Supplying more oxygen
Supplying more hydrogen
Supplying more protons
Supplying more cells
What is the process of refuelling a fuel cell vehicle?
Options:
Refuel with water
Plug it into an electric charging station
Pump hydrogen into the fuel tank
Fill the tank with gasoline.
What percentage of the known universe is composed of hydrogen?
Options:
75%
50%
99%
25%
Answers
d. Electrochemical reactions. Fuel cells produce electricity via electrochemical reactions similar to a battery without combustions. However, contrary to a battery, a fuel cell does not wear out as long as there is a continuous fuel source.
b. Fuel cells only emit water, heat, and energy.
d. Multiple fuel cells are merged to come up with fuel cell stack to boost the amount of electricity produced. As one fuel cell can produce nearly one volt of electricity, the stack can create more.
c. To refuel a fuel cell vehicle, you need to fill the tank with hydrogen directly from a fuel station.
a. 75%.
Hydrogen Fuel Production
As said earlier, even though hydrogen is abundantly available in the atmosphere, it is not found in its pure form. Hydrogen composes almost 75% of all substances present in the universe. However, for an industrial scale of usage, it needs to be present as primary energy.
Here are some conventional methods for the production of hydrogen fuel.
Besides these methods, some other hydrogen production processes are in developmental or research phase. Some of these methods are the photobiological, high-temperature, and also photoelectrochemical splitting of water.
Uses of Hydrogen Fuel
The main uses of hydrogen fuel cells are an alternative power option for aeroplanes, cars, boats, etc. It can be used as a portable or stationary application of fuel cell that can power electric motors. However, it is not easy to store H2 in high pressure or cryogenic tank. And that is a primary problem of considering hydrogen fuel cell in vehicles.
Quiz 2.0
Which are the most popular methods to produce hydrogen fuel?
Options:
Quantum mechanics
Thermal conductivity
Electrolysis and steam reforming
Electrolysis and absorption
In which year the first-ever fuel cell was invented?
Options:
1920
1789
1894
1839
What are the by-products of the fuel cell system?
Options:
Water vapour and heat.
Water and carbon dioxide.
Water and carbon monoxide.
Water and hydrogen monoxide.
Which one is the major setback of the fuel cell mechanism?
Options:
Pollution
Weight
Cost
Longevity
Where in a fuel cell are hydrogen ions produced?
Options:
Anode
Cathode
The positive terminal of a battery
Electrolyte centre
Answers
c. Electrolysis and steam reforming are the two most cost-effective and common processes to produce hydrogen.
d. In the year 1839, Sir William Robert Grove invented first-ever fuel cell.
a. Water vapour and heat are the by-products of this fuel cell system.
c. Cost is one of the significant downsides of this mechanism.
a. Hydrogen ions are generated in the anode cell.
Hydrogen Economy
Hydrogen economy implies a vision of considering hydrogen as an alternative power generator with low-carbon emission. For example, one of the objects of this fuel cell is to replace natural gasses as heating fuels or gasoline as a fuel for transportation.
The elemental benefit of this system is that here hydrogen instead of electricity transmits the energy.
In present day, it is operated by combining with natural gasses to enhance efficiency. Moreover, in the near future, this fuel is expected to be used widely.
Hydrogen Fuel: Advantages
The main advantage of a hydrogen fuel cell is that it only emits water. Thus, it is eco-friendly.
While burning, hydrogen does not generate carbon dioxide.
Electrolysis and steam reforming
The fuel cell engines are more efficient than an internal combustion engine.
Now, you must have understood the importance of hydrogen fuel cell in human life as well as the environment. If you need any more information about what is a hydrogen fuel cell and its uses, advantages, etc., you can visit our Vedantu website today. You can also download our Vedantu app for easier access.
FAQs on Hydrogen Fuel Cell Working Principle and Reactions
1. What is a hydrogen fuel cell?
A hydrogen fuel cell is an electrochemical device that converts the chemical energy of hydrogen and oxygen directly into electricity, producing water as the only by-product. It works without combustion and generates electrical energy through redox reactions. Key points include:
- Fuel: H2(g)
- Oxidant: O2(g)
- Main product: H2O(l)
- Energy conversion: chemical energy → electrical energy
Hydrogen fuel cells are widely studied in electrochemistry, green chemistry, and clean energy technology.
2. How does a hydrogen fuel cell work?
A hydrogen fuel cell works by oxidizing hydrogen at the anode and reducing oxygen at the cathode to generate electricity. The process involves separate half-reactions:
- Anode (oxidation): H2(g) → 2H+(aq) + 2e-
- Cathode (reduction): ½O2(g) + 2H+(aq) + 2e- → H2O(l)
- Overall reaction: 2H2(g) + O2(g) → 2H2O(l)
Electrons flow through an external circuit, producing electric current, while protons move through an electrolyte to complete the circuit.
3. What is the overall chemical equation for a hydrogen fuel cell?
The overall balanced chemical equation for a hydrogen fuel cell is 2H2(g) + O2(g) → 2H2O(l). This reaction represents the combination of hydrogen and oxygen to form water. Important points:
- It is a redox reaction.
- Hydrogen is oxidized and oxygen is reduced.
- The reaction releases energy as electrical energy rather than heat (as in combustion).
This same equation also describes hydrogen combustion, but in a fuel cell the energy is harnessed electrochemically.
4. What are the half-reactions in a hydrogen fuel cell?
The half-reactions in a hydrogen fuel cell are oxidation at the anode and reduction at the cathode. In an acidic proton exchange membrane (PEM) fuel cell:
- Anode: H2(g) → 2H+(aq) + 2e-
- Cathode: ½O2(g) + 2H+(aq) + 2e- → H2O(l)
These half-reactions show the transfer of electrons and protons, which is central to electrochemistry and galvanic cell operation.
5. What is the difference between a hydrogen fuel cell and electrolysis of water?
The key difference is that a hydrogen fuel cell produces electricity from hydrogen, while electrolysis uses electricity to produce hydrogen. The reactions are reverse processes:
- Fuel cell: 2H2(g) + O2(g) → 2H2O(l) (electricity produced)
- Electrolysis: 2H2O(l) → 2H2(g) + O2(g) (electricity consumed)
In electrolysis, an external power source drives a non-spontaneous reaction, whereas a fuel cell operates as a spontaneous galvanic cell.
6. What type of redox reaction occurs in a hydrogen fuel cell?
A hydrogen fuel cell involves a spontaneous redox reaction where hydrogen is oxidized and oxygen is reduced. Specifically:
- Oxidation: H2 loses electrons to form H+.
- Reduction: O2 gains electrons to form H2O.
Because electrons flow through an external circuit, the reaction functions as a galvanic (voltaic) cell, converting chemical energy into electrical energy.
7. What are the main components of a hydrogen fuel cell?
The main components of a hydrogen fuel cell are the anode, cathode, electrolyte, and external circuit. In a typical proton exchange membrane (PEM) fuel cell:
- Anode: Site of hydrogen oxidation
- Cathode: Site of oxygen reduction
- Electrolyte (PEM): Conducts H+ ions but blocks electrons
- Catalyst: Usually platinum (Pt) to increase reaction rate
These components ensure controlled redox reactions and continuous electricity generation.
8. Why is a hydrogen fuel cell considered environmentally friendly?
A hydrogen fuel cell is considered environmentally friendly because its only direct by-product is water (H2O). Key environmental benefits include:
- No emission of CO2, SO2, or NOx during operation
- High energy efficiency compared to combustion engines
- Quiet operation with minimal pollutants
However, the overall environmental impact depends on how the hydrogen fuel is produced (e.g., steam reforming vs renewable electrolysis).
9. What is the standard cell potential of a hydrogen fuel cell?
The standard cell potential (E°cell) of a hydrogen fuel cell under standard conditions is approximately +1.23 V. This value is calculated from standard reduction potentials:
- O2 + 4H+ + 4e- → 2H2O E° = +1.23 V
- 2H+ + 2e- → H2 E° = 0.00 V (standard hydrogen electrode)
The positive E°cell indicates a spontaneous reaction under standard conditions.
10. What are the advantages and disadvantages of hydrogen fuel cells?
Hydrogen fuel cells offer high efficiency and clean energy production, but they also have cost and storage challenges. Key advantages and disadvantages include:
- Advantages:
- High efficiency (chemical → electrical energy)
- Only water as exhaust product
- Continuous operation with fuel supply
- Disadvantages:
- High cost of platinum catalysts
- Hydrogen storage and transportation difficulties
- Hydrogen production may involve fossil fuels
Understanding these factors is important when comparing hydrogen fuel cells with batteries and internal combustion engines.
