What Is Hydrogen Combustion?
Hydrogen combustion engines are effectively very similar to a regular gasoline combustion engine. Fuel goes in, gets compressed and mixed with oxygen, a spark creates ignition, and boom: power.
However, the combustion process of hydrogen results in less CO2 production than gasoline combustion because there is little to no carbon present (gasoline is a carbon-based fuel, whereas hydrogen is, well, hydrogen). Instead, the hydrogen bonds to oxygen molecules during the combustion process, and the primary emission from the exhaust is water.
When hydrogen combusts, it creates a pretty robust explosion, which has been idealized as a fuel for combustion vehicles for quite some time, especially as governments push to ban carbon dioxide emissions.
But hydrogen combustion driving the wheels, like regular combustion, is less energy efficient than using combustion as a generator. Whereas EVs have an approximate energy efficiency of 75-85%, and hydrogen fuel cells are between 50-60%, hydrogen combustion is rated at efficiency of just 40-45%, according to a report from McKinsey, making it similar to diesel. The upside is that its emissions are far cleaner than diesel or regular gasoline combustion.
History Of Hydrogen Combustion Vehicles
Hydrogen combustion hasn’t yet become viable, but that doesn’t mean it hasn’t been invested in for years. While hydrogen combustion can trace its roots back to the De Rivaz engine of 1807 and the Hippomobile of 1863, it wasn’t until the early 1970s that Tokyo City University started pioneering hydrogen combustion vehicle concepts with the Musashi-1. But mainstream automakers have also invested in hydrogen combustion, and since the early 1990s, dozens of developmental prototypes have looked into the technology’s viability.
Mazda, for example, ran a fleet of hydrogen combustion RX-8 prototypes in Germany and Japan in the late 2000s; using a direct injection system on the 13B Renesis engine enabled hydrogen to fuel the rotary motor without any other necessary changes to its architecture. Before this, a 1993 Miata was run with a hydrogen rotary engine, some two years after Mazda’s very first HR-X hydrogen rotary concept.
Traditionally, this development has focused on gaseous hydrogen, but liquid hydrogen as a fuel has also been researched, most recently by Toyota but previously by BMW as well.
