Many experts predict that we’ll soon be employing fuel cells to provide electricity for a variety of everyday items.
An electrochemical process, rather than combustion, is how a fuel cell produces electricity. Hydrogen and oxygen are mixed in a fuel cell to produce electricity, heat, and water.
Today, a variety of vehicles, including cars, buses, trucks, forklifts, trains, and more, are moved by the use of fuel cells. These vehicles include trains, forklifts, hospitals, grocery stores, and other critical infrastructure facilities.
What Are Fuel Cells
A fuel cell is an electrochemical device that uses two redox processes to transform the chemical energy of a fuel (typically hydrogen) and an oxidizing agent (commonly oxygen) into electrical energy.
In contrast to most batteries, fuel cells require a constant supply of fuel and oxygen (typically from the air) to sustain the chemical reaction. In contrast, a battery typically derives its chemical energy from materials that are already present in the battery. As long as fuel and oxygen are available, fuel cells can constantly create electricity.
A fuel cell generates electricity cleanly and effectively by utilizing the chemical energy of hydrogen or other fuels. Electricity, water, and heat are the only byproducts if hydrogen is the fuel. In terms of the diversity of potential applications, fuel cells are exceptional; they can run on a variety of fuels and feedstocks and can power devices as big as utility power plants and as tiny as laptop computers.
A clean, effective, dependable, and silent source of energy is a fuel cell system. Unlike batteries, which require periodic recharge, fuel cells can continue to generate power as long as a fuel source is available.
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How Fuel Cells Work
Fuel cells function like batteries but do not need to be recharged or run down. As long as fuel is available, they generate heat and electricity. Two electrodes—a negative electrode (also known as the anode) and a positive electrode (also known as the cathode) sandwiched around an electrolyte make up a fuel cell.
The anode receives fuel, such as hydrogen, while the cathode receives air. A catalyst at the anode of a hydrogen fuel cell splits hydrogen molecules into protons and electrons, which travel via several routes to the cathode.
Electrons traverse an external circuit, causing an electricity flow. Protons move from the electrolyte to the cathode through the electrolyte, where they combine with oxygen and electrons to create heat and water.
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What are the Types of Fuel Cells?
Although fuel cells all function in much the same ways, variants have benefited from various electrolytes and meet a variety of application requirements.
The idea is the same whether the fuel or the charged species moving through the electrolyte are different. At the anode, oxidation takes place, whereas, at the cathode, a reduction takes place.
A charged species that travel through the electrolyte and electrons that move through the external circuit connect the two reactions.
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8 Types of Fuel Cells and How They Work
The following are eight types of fuel cells and how they work:
- Polymer Electrolyte Membrane Fuel Cells
Proton-conducting polymer membranes are used as the electrolyte in polymer electrolyte membrane (PEM) fuel cells, also known as proton exchange membrane fuel cells. Typically, hydrogen is used as the fuel.
These cells operate at relatively low temperatures and can swiftly alter their output to meet shifting power demands. The best fuel cells to use to power cars are PEM fuel cells.
They can also generate stationary power. They cannot, however, directly burn hydrocarbon fuels like natural gas, liquefied natural gas, or ethanol because of their low operating temperature. For usage in a PEM fuel cell, these fuels need to be transformed into hydrogen in a fuel reformer.
- Direct – Methanol Fuel Cells
Because it uses a proton-conducting polymer membrane as an electrolyte, the direct-methanol fuel cell (DMFC) is comparable to the PEM cell. However, DMFCs do not require a fuel reformer because they use methanol directly on the anode.
DMFCs are of interest for powering portable electronic equipment, including laptop computers and battery rechargers. Methanol is a desirable fuel for portable electronics because it has a higher energy density than hydrogen.
- Alkaline Fuel Cells
An alkaline electrolyte, such as potassium hydroxide, or an alkaline membrane that conducts hydroxide ions rather than protons, is used in alkaline fuel cells.
Alkaline fuel cells, which were first used by the National Aeronautics and Space Administration (NASA) on space missions, are now seeing new uses, such as in portable electricity.
- Phosphoric Acid Fuel Cells
Phosphoric acid fuel cells work at a temperature of around 200 °C and employ a phosphoric acid electrolyte that conducts protons contained inside a porous matrix. In hotels, hospitals, supermarkets, and office buildings, where waste heat can also be utilized, they are often used in modules of 400 kW or more for stationary power production.
It is also possible to encapsulate phosphoric acid in polymer membranes, and fuel cells that use these membranes are appealing for several stationary power applications.
- Molten Carbonate Fuel Cells
A molten carbonate salt immobilized in a porous matrix that conducts carbonate ions serves as the electrolyte for molten carbonate fuel cells.
Their great efficiency results in net energy savings in a variety of medium-to-large stationary applications where they are already in use. They may internally reform fuels like natural gas and biogas because of their high-temperature functioning (about 600°C).
- Solid Oxide Fuel Cells
A thin ceramic layer serves as a solid electrolyte for solid oxide fuel cells, conducting oxide ions. Besides auxiliary power equipment for heavy-duty trucks, they are being developed for a range of stationary power applications.
These fuel cells can internally reform natural gas and biogas and can be coupled with a gas turbine to provide electrical efficiencies as high as 75% while operating at 700°C–1,000°C with zirconia-based electrolytes and as low as 500°C with ceria-based electrolytes.
- Combined Heat and Power Fuel Cells
Fuel cells also generate heat besides electricity. They can accomplish hot water and room heating with the help of this heat.
When used to power homes and buildings, combined heat and power fuel cells can achieve overall efficiencies of up to 90%. This energy-efficient operation lowers greenhouse gas emissions while saving money and energy.
- Reversible or Regenerative Fuel Cells
This type of fuel cell generates electricity from hydrogen and oxygen, but it also can operate in reverse, using electricity to generate hydrogen and oxygen.
With the help of this innovative technology, excess energy generated by intermittent renewable energy sources like wind and solar power plants might be stored and released when power production is low.
Brief History of Fuel Cells
Fuel cells powered by hydrogen were originally mentioned in 1838. Welsh scientist and lawyer Sir William Grove talked about the creation of his first primitive fuel cells in a letter that was dated October 1838 but appeared in the December 1838 issue of The London and Edinburgh Philosophical Magazine and Journal of Science. He combined sheet iron, copper, and porcelain plates with a sulphate of copper and weak acid solution.
German physicist Christian Friedrich Schönbein discussed his first rudimentary fuel cell in a letter to the same journal that was written in December 1838 but published in June 1839. He wrote about a current produced by oxygen and hydrogen dissolved in water. Grove later drew his own design in the same journal in 1842. He created a fuel cell using components that are still used in phosphoric acid fuel cells today.
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8 Fuel Cell Components
The following are some of the parts or components of Fuel Cells:
- Catalyst
- Electrodes
- Gas Diffusion Layers
- Membrane Electrode Assemblies (MEA)
- Membranes
- Dispersions
- Gasketing
- Plates
Why Study Fuel Cells
Fuel cells have a wide range of uses, including producing electricity for transportation, commercial, industrial, and residential structures, as well as long-term energy storage for the grid in reversible systems.
Compared to traditional combustion-based technologies, which are now employed in many power plants and automobiles, fuel cells provide several advantages.
Also, compared to combustion engines, fuel cells have superior operating efficiency and can directly convert the chemical energy in fuel into electrical energy at rates over 60%.
Fuel cells emit either no emissions or very little compared to combustion engines. Because there are no carbon dioxide emissions from hydrogen fuel cells, they can effectively solve serious climate concerns. Additionally, the point of operation is free of air contaminants that lead to smog and health issues. Because of their lack of moving parts, fuel cells are rather silent when operating.
Research and Development as it Concerns Fuel Cells
They include:
- In the year 2005, Triazole was used by Georgia Institute of Technology researchers to increase the operating temperature of PEM fuel cells from below 100 °C to above 125 °C, with the assertion that doing so will reduce the need to purify the hydrogen fuel with carbon monoxide.
- In the year 2008, PEDOT was employed as a cathode by Monash University in Melbourne.
- In the year 2009, scientists from the University of Dayton in Ohio showed how fuel cell catalysts made of arrays of vertically grown carbon nanotubes might be employed.
- A catalyst for fuel cells based on nickel bisphosphine was shown in the same year.
- In the year 2013, the British company ACAL Energy created a fuel cell that it claimed could operate for 10,000 hours under realistic driving circumstances. It claimed that the price of building a fuel cell could be lowered to $40/kW (approximately $9,000 for 300 HP).
- In the year 2014, A novel technique for the regeneration of PEFCs polluted by hydrogen sulfide was devised by researchers at Imperial College London. A PEFC that had been contaminated with hydrogen sulfide could work at 95 to 100 percent of its prior capacity. They also had success restoring a PEFC that had been poisoned with SO2. They can regenerate multiple cell stacks using this technique.
Conclusion
Fuel cells are vital to the energy industry. They can provide heat and electricity for buildings and electrical power for vehicles and electronic devices.
Besides that, today, a variety of vehicles, including cars, buses, trucks, forklifts, trains, and more use fuel cells to move.
