Hydrogen is a relatively new player in the alternative fuel market, offering an alternative to electric cars and hybrids with its own take on green emissions. However, hydrogen-powered technology sadly hasn’t taken off as of 2025, owing to a number of factors such as lack of infrastructure, safety concerns, and the expense associated with purchasing a relatively specialized, low-volume production car. That said, hydrogen power remains quite versatile and full of unrealized potential, with cars mainly utilizing one of two means of producing power: hydrogen fuel cells, and hydrogen-powered internal combustion engines (ICE).
While these both feature the common fuel source of hydrogen, the way each powerplant actually functions differs as drastically as comparing electric motors to gas-powered engines. Hydrogen fuel cells started the nascent movement, and remain the most well-known of the two powertrains. For example, the Toyota Mirai is the world’s first mass-market hydrogen fuel cell (FCEV)-powered car, debuting for model year 2014 and still available today in American markets. These cars are functionally similar to electric cars, merely drawing energy from hydrogen fuel cells instead of batteries.
Meanwhile, the hydrogen-powered internal combustion engine effectively functions identically to a normal combustion engine, right down to the sound and general performance characteristics. For all intents and purposes, a hydrogen ICE is simply a regular engine that just runs on a unique fuel. Of course, actually converting a gas-powered engine to run on hydrogen is another matter entirely. Let’s discuss how each of these powertrains works in detail, beginning with the more “typical” of the two: the hydrogen FCEV.
How hydrogen fuel cells work
All electric motors need two principal factors to run: a means of generating electricity, and a fuel source. With most EVs, this is typically performed by marrying DC electric traction motors with large rechargeable battery packs. Modern FCEVs use batteries as well, providing supplemental power and regenerative braking capability. Meanwhile, the main driving force behind the electric motors is the fuel cell itself, which converts hydrogen into electricity.
To illustrate how this occurs, we first begin at the compressed hydrogen fuel tank, functionally-identical to any other fuel tank. Hydrogen is then drawn into the fuel cell, which contains a catalyst that separates the hydrogen atoms into a proton and electron. The electrons are then drawn by the current collector, which itself connects to the car’s high-voltage systems — namely, the electric motor. The fuel cell itself is most often composed of a polymer electrolyte membrane. The electrolyte membrane is sandwiched between a cathode and an anode; put simply, hydrogen is introduced to the anode, and oxygen to the cathode. This causes the protons and electrons to separate, with the protons sticking back while the electrons perform work. Once these electrons finish, they travel back and recombine with the protons, creating water.
Hydrogen FCEVs date back to 1966, known as the Electrovan by General Motors. This revolutionary design utilized a fuel cell that combined liquid hydrogen and liquid oxygen, as opposed to combining pressurized hydrogen with ambient oxygen from the air. Toyota remains the most prominent manufacturer of hydrogen FCEVs with the company’s long-standing Toyota Mirai, though these days it faces competition from Honda and Hyundai in American markets.
Hydrogen combustion engines
While hydrogen FCEVs represent the bulk of the hydrogen market, this represents a more lucrative option for those looking for the traditional sound and feel of a standard combustion engine. That’s because the hydrogen-powered internal combustion engine functions exactly as it sounds: it is a typical engine, just powered by hydrogen. Like most common engines found in passenger cars today, hydrogen engines can be in any number of configurations and cylinder counts, and share most common parts such as the engine block, crankshaft, and cylinder heads. They typically function on a normal four-stroke power cycle, with injection, compression, a power stroke, and exhaust. Various manufacturers like Toyota and Cummins invest in hydrogen engine technology for use in everything from heavy-duty trucks and construction equipment to bespoke race cars.
Because engines use so many common parts, it is technically possible to convert a regular engine to run on hydrogen; the main difference between the two is, fairly obviously, the fuel. However, it’s not just the explosive properties that are different, but also how the fuel is delivered; hydrogen is a gas, while gasoline is a liquid. These elements require different storage, with hydrogen requiring a pressurized tank, and specialized fuel delivery systems such as lines and injectors.
The most-anticipated issues to its implementation are idiosyncrasies in the engine such as cylinder imbalance, as well as a lack of meaningful levels of infrastructure across the globe. However, as a developing technology requiring relatively minor modifications to existing engines, it presents one of the most viable means of ditching gasoline for good — all without ditching its signature sound as a welcome bonus. Hydrogen ICE cars represent a minority, though various models of FCEV cars are available for those looking to swap anyway.
