The industry has spent two decades perfecting the diesel compression ignition engine. But now, in the push for zero carbon, OEMs are releasing "Hydrogen Internal Combustion Engines" (H2-ICE). These look like diesel blocks, but they run on hydrogen gas and use spark plugs. This is sending mechanics back to school for skills that died out in the 1950s.
H2-ICE engines are not fuel cells; they burn fuel in a cylinder. Because hydrogen has a very high octane rating but requires an ignition source (it doesn't auto-ignite like diesel), these engines are equipped with high-voltage ignition coils and spark plugs-components that haven't existed on heavy excavators for generations.
The mechanical reality is vastly different from diesel. Hydrogen combustion produces massive amounts of water vapor. If the engine runs at low load for too long (idling), the water doesn't evaporate out of the exhaust; instead, it washes down past the rings and mixes with the engine oil. Mechanics are finding oil pans filled with a milky, white mayonnaise emulsion in just a few hours of light work. The oil analysis labs are overloaded with samples showing "water in oil" numbers that would condemn a diesel engine instantly. For H2-ICE machines, "normal" operation now requires running the engine hard to generate enough exhaust heat to keep the cylinders dry, or installing heavy-duty crankcase breathers to separate the water vapor before it contaminates the pan.
