Check out these pages for information about how fuel cells can be used for a variety of purposes today:

Fuel Cell Basics

A fuel cell is a device that generates electricity through an electrochemical reaction, not combustion. In a fuel cell, hydrogen and oxygen are combined to generate electricity, heat, and water. Fuel cells are used today in a range of applications, from providing power to homes and businesses, keeping critical facilities like hospitals, grocery stores, and data centers up and running, and moving a variety of vehicles including cars, buses, trucks, forklifts, trains, and more.

Fuel cell systems are a clean, efficient, reliable, and quiet source of power. Fuel cells do not need to be periodically recharged like batteries, but instead continue to produce electricity as long as a fuel source is provided.

A fuel cell is composed of an anode, cathode, and an electrolyte membrane. A typical fuel cell works by passing hydrogen through the anode of a fuel cell and oxygen through the cathode. At the anode site, a catalyst splits the hydrogen molecules into electrons and protons. The protons pass through the porous electrolyte membrane, while the electrons are forced through a circuit, generating an electric current and excess heat. At the cathode, the protons, electrons, and oxygen combine to produce water molecules. As there are no moving parts, fuel cells operate silently and with extremely high reliability.

Due to their chemistry, fuel cells are very clean. Fuel cells that use pure hydrogen fuel are completely carbon-free, with their only byproducts being electricity, heat, and water. Some types of fuel cell systems are capable of using hydrocarbon fuels like natural gas, biogas, methanol, and others. Because fuel cells generate electricity through chemistry rather than combustion, they can achieve much higher efficiencies than traditional energy production methods such as steam turbines and internal combustion engines. To push the efficiency even higher, a fuel cell can be coupled with a combined heat and power system that uses the cell’s waste heat for heating or cooling applications.

Fuel cells are also scalable. This means that individual fuel cells can be joined with one another to form stacks. In turn, these stacks can be combined into larger systems. Fuel cell systems vary greatly in size and power, from combustion engine replacements for electric vehicles to large-scale, multi-megawatt installations providing electricity directly to the utility grid.

Listed below are a few of the most commonly used fuel cells and the characteristics that make them unique.

Alkaline Fuel Cell (AFC)

AFCs are best known for their roles in the NASA Apollo mission to provide both water and electricity to the crew. These fuel cells use porous electrolytes saturated with an alkaline solution and have an alkaline membrane as the name suggests. The AFC is one of the most efficient types of fuel cells, with a potential of 60% electrical efficiency, and 80% to 90% in CHP applications. AFCs use hydrogen as a fuel source, though are highly sensitive and can fail when exposed to carbon dioxide, which is why they are primarily used in controlled aerospace and underwater applications.

Phosphoric Acid Fuel Cell (PAFC)

PAFCs use a liquid phosphoric acid and ceramic electrolyte and a platinum catalyst. Theses fuel cells operate physically similar to the PEM fuel cell and at similar efficiency level. However, PAFCs run at a higher temperature, allowing them to handle small amounts of fuel impurities. PAFCs are typically used in a cogeneration mode to not only produce electricity, but also heat to be captured to assist heating and cooling. PAFCs are often seen in high-energy demand applications, such as hospitals, schools and manufacturing and processing centers.

Molten Carbonate Fuel Cell (MCFC)

Molten Carbonate Fuel Cells (MCFCs) operate at temperatures upwards of 1200 degree Fahrenheit, utilizing a molten carbonate-salt mixture suspended in a ceramic matrix as an electrolyte. This high temperature allows for MCFCs to utilize non-platinum catalysts through a process called ‘internal reforming,’ decreasing overall system cost. MCFCs can also use natural gas directly as its fuel source, as its high temperatures allow internal reforming of the natural gas into hydrogen within the system itself. MCFCs can reach efficiencies of 50-60%, and 70% - 80% in CHP applications. These fuel cells are typically deployed in stationary applications, providing high-quality primary and back-up power to utilities and businesses.

Proton Exchange Membrane Fuel Cell

Proton Exchange Membrane Fuel Cells (PEMFCs) use a polymer membrane for its electrolyte and a precious metal, typically platinum, for its catalyst. What distinguishes these fuel cells from others is PEMFC’s ability to operate at cooler temperatures relative to other types of fuel cells, between 80 to 200 degrees Fahrenheit. Pure hydrogen gas is the typical fuel for PEMFCs Due to their use of precious metals and lower operating temperatures.

PEMFCs operate between 40% to 60% efficiency and are capable of handling large and sudden shifts in power output. PEMFCs are well-suited for cars and other specialty vehicles such as forklifts that need to quickly start up or accelerate. Additionally, PEMFC’s can be scaled in stationary applications for use in telecommunications, data centers, and residential markets.

Solid Oxide Fuel Cell (SOFC)

SOFCs are the highest temperature fuel cells, operating at about 1800 degrees Fahrenheit. SOFCs use a dense layer of ceramic as an electrolyte, which at high temperatures allows for the conductivity of oxygen ions. Similar to the MCFCs, SOFCs also use a non-platinum catalyst utilizing internal reformation, and are commonly fueled by natural gas. Through this process, SOFCs can achieve electrical efficiencies of 50% to 60%, and 70%-80% in CHP applications. SOFCs are being used in a range of applications, from small residential auxiliary power units supplying heat and power to homes, to large-scale stationary power generators for larger buildings and businesses.

Direct Methanol Fuel Cell (DMFC)

Much like PEMFCs, Direct Methanol Fuel Cells (DMFCs) use a polymer membrane as an electrolyte and commonly a platinum catalyst as well. However, unlike PEMFCs, DMFCs draw hydrogen from liquid methanol, rather than use direct hydrogen fuel. DMFCs also run at relatively cool temperatures, between 125 and 250 degrees Fahrenheit. . Applications of DMFCs range from small electronics, such as battery chargers and laptops, to larger applications like stationary power for telecommunications backup.

Benefits at a glance:

Low-to-Zero Emissions
High Efficiency
Reliability
Fuel Flexibility
Energy Security
Durability
Scalability
Quiet Operation

For more information on hydrogen, please see our Hydrogen Basics.

To learn more about the many applications of fuel cells, please see the pages below.

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Fuel Cell & Hydrogen Energy Association

Fuel Cell Basics

Fuel Cell Basics