Examples of Fuel Cells

Common examples of fuel cells include proton-exchange membrane fuel cells (PEMFC), solid oxide fuel cells (SOFC), phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), alkaline fuel cells (AFC), and direct methanol fuel cells (DMFC). In practice, you’ll find them powering cars like the Toyota Mirai, heavy trucks from Nikola and Hyundai, stationary power systems from Bloom Energy, buses across Europe and the UK, hydrogen trains such as Alstom’s Coradia iLint, and even ferries like Norway’s MF Hydra. Fuel cells vary by electrolyte, temperature, and fuel used, enabling diverse applications from portable electronics to grid-scale power.

Core types of fuel cells and what distinguishes them

Fuel cells are categorized primarily by their electrolyte and operating temperature, which determine their efficiency, durability, fuel flexibility, warm-up time, and best-fit applications. Below are the principal types used or demonstrated today, with typical characteristics and use cases.

• Proton-Exchange Membrane Fuel Cells (PEMFC, PEFC): Low temperature (~60–90°C) with high-temperature variants (~120–180°C). Fast start-up, high power density; widely used in vehicles, buses, backup power, and emerging data center systems.
• Solid Oxide Fuel Cells (SOFC): High temperature (~600–900°C). High electrical efficiency, can utilize hydrogen or reform hydrocarbons (e.g., natural gas, biogas). Common in stationary power, combined heat and power (CHP), and some maritime demonstrators.
• Phosphoric Acid Fuel Cells (PAFC): Medium temperature (~150–220°C). Mature stationary systems for CHP, especially in commercial buildings.
• Molten Carbonate Fuel Cells (MCFC): High temperature (~600–700°C). Suitable for large stationary power and CHP; can run on hydrogen, biogas, or reformed natural gas; often sited at industrial or utility-scale facilities.
• Alkaline Fuel Cells (AFC): Low temperature (~60–90°C). Historically used in space applications; modern variants target stationary and niche uses, sensitive to CO₂ in air unless managed.
• Direct Methanol Fuel Cells (DMFC): Low to medium temperature (~50–120°C). Use liquid methanol; popular for portable/off-grid power and specialty applications.
• Direct Ethanol/Formic Acid Fuel Cells (DEFC/DFAFC): Low temperature. Research and niche products leverage easier-to-handle liquid fuels; power densities remain lower than PEMFC.
• Solid Acid Fuel Cells (SAFC): Intermediate temperature (~150–300°C). Emerging class aiming to combine some benefits of PEM and high-temp systems for stationary use.
• Reversible Fuel Cells (URFC) and Reversible Solid Oxide Cells (RSOC): Operate both as electrolyzers (to make hydrogen) and as fuel cells (to generate electricity), enabling energy storage and grid balancing.
• Microbial Fuel Cells (MFC): Use bacteria to generate electricity from organic matter; primarily experimental for low-power sensors and wastewater treatment pilots.

Together, these types span low to high temperatures and from portable to utility-scale uses, enabling designers to match the chemistry and operating conditions to the job at hand.

Examples by fuel and oxidant

While oxygen from air is the standard oxidant, fuel cells can use different fuels, each with trade-offs in energy density, handling, emissions, and system complexity. Here are representative examples organized by fuel.

• Hydrogen fuel cells (PEMFC, SOFC): The most common modern setup; hydrogen provides zero CO₂ at the point of use. PEMFC dominate mobility and backup power; SOFC offer high-efficiency stationary generation.
• Methanol fuel cells (DMFC): Use liquid methanol directly—handy for off-grid portable power and remote sensors where liquid fuel logistics are easier than compressed hydrogen.
• Formic acid and ethanol fuel cells (DFAFC/DEFC): Liquid fuels with simpler storage than H₂; used in niche portable systems and research prototypes.
• Ammonia fuel cells: Either crack ammonia to hydrogen for PEMFC/SOFC or use direct-ammonia designs (early-stage). Attractive for energy-dense, shippable hydrogen carriers with zero carbon at point of use.
• Hydrocarbon/biogas-capable fuel cells (SOFC/MCFC): Can internally reform methane, propane, or biogas, allowing distributed generation with existing fuel infrastructure and lower lifecycle emissions when using biogas.
• Wastewater/biological fuels (MFC): Generate small amounts of power from organic waste streams; mainly for demonstrations and specialized sensing.

Fuel choice influences not only emissions and energy density but also balance-of-plant needs (e.g., reformers or crackers), start-up time, and maintenance, driving the best match between fuel and application.

Notable commercial and fielded systems (as of 2025)

Beyond laboratory examples, fuel cells are operating in real-world vehicles, vessels, trains, buildings, and telecom networks. The following highlights widely reported deployments and products across sectors.

• Passenger vehicles: Toyota Mirai (PEMFC) and Hyundai Nexo (PEMFC) are the most visible fuel-cell electric cars available in select markets with hydrogen fueling infrastructure.
• Heavy-duty trucks: Nikola Tre FCEV in North America and Hyundai XCIENT Fuel Cell fleets in Europe and the U.S. demonstrate long-range, fast-refueling freight operations with hydrogen.
• Buses: Fuel-cell buses powered by Ballard- and other PEM stacks run in the UK, Germany, France, the Nordics, North America, and East Asia, offering zero-emission urban transit.
• Trains: Alstom’s Coradia iLint hydrogen fuel-cell trains entered passenger service in Germany; Stadler’s FLIRT H2 has undergone testing in California for regional rail service.
• Maritime: Norled’s MF Hydra in Norway operates as the world’s first liquid-hydrogen ferry with fuel-cell propulsion; other pilot vessels use PEM or SOFC for auxiliary and hybrid power.
• Aviation demonstrators: ZeroAvia has flight-tested hydrogen-electric powertrains on a 19-seat Dornier 228 platform, advancing towards regional aircraft certification pathways.
• Stationary power (SOFC/PAFC/MCFC): Bloom Energy servers (SOFC) supply reliable power and CHP for hospitals, manufacturers, and data centers; Doosan Fuel Cell (PAFC) units are widely deployed in South Korea; FuelCell Energy’s MCFC platforms support multi-megawatt projects such as long-running installations in the U.S.
• Telecom and backup power: Plug Power’s GenSure (PEM) and similar systems provide long-duration backup for cell towers and critical infrastructure, offering cleaner alternatives to diesel gensets.
• Portable/off-grid: SFC Energy’s EFOY (DMFC) generators power remote sensors, mobile labs, and recreational/off-grid applications using easily stored liquid methanol.

These deployments illustrate how fuel cells serve distinct niches—from fast-refueling, long-range mobility to resilient, low-emission on-site power—often where batteries alone face constraints in range, refueling time, or duty cycle.

How fuel cells are commonly categorized

To navigate the variety of designs on the market and in research, it helps to understand the main classification schemes engineers use.

1. By electrolyte and operating temperature: Determines kinetics, materials, warm-up time, and durability (e.g., PEMFC vs SOFC vs MCFC).
2. By fuel: Hydrogen, ammonia (direct or cracked), methanol, formic acid, ethanol, natural gas/biogas for high-temperature systems.
3. By application: Portable, backup/telecom, stationary CHP, mobility (cars, buses, trucks, trains, ships), and aerospace.
4. By reversibility: Conventional fuel cells vs URFC/RSOC systems that also operate as electrolyzers for energy storage.

These categories guide technology selection and system design, ensuring the fuel cell’s characteristics align with performance, cost, and infrastructure needs.

What sets different examples apart

Low-temperature PEMFCs excel in fast, on-demand power for vehicles and backup; high-temperature SOFCs and MCFCs deliver high efficiency and useful heat for buildings or industry; liquid-fueled DMFCs simplify logistics for small, remote loads. Advances in catalysts, membranes, and stack manufacturing continue to lower costs and improve durability, broadening where each type can compete.

Summary

Examples of fuel cells span PEMFC, SOFC, PAFC, MCFC, AFC, and DMFC, with newer variants like SAFC and reversible systems. Real-world deployments include passenger cars (Toyota Mirai, Hyundai Nexo), heavy trucks (Nikola, Hyundai), buses, hydrogen trains (Alstom iLint), ferries (MF Hydra), and stationary power from firms like Bloom, Doosan, and FuelCell Energy. Choice of type and fuel—hydrogen, methanol, ammonia, biogas—drives suitability for applications ranging from portable devices to utility-scale power and long-range transport.