Hydrogen Internal Combustion Engine (ICE) vehicles are different from hydrogen fuel cell vehicles (FCV) – they are simply a modified version of the traditional gasoline-powered internal combustion engine. These hydrogen engines burn fuel in the same manner that gasoline engines do – 1kg of hydrogen has the same energy content of 3.8 litres of gasoline, about 130MJ.
Hydrogen combustion engines are particularly sensitive to transients in load, in terms of efficiency, and therefore more suited to constant load operations. As such, its direct application is in the transportation sector, particularly for long-haul and heavy duty commercial vehicles.
The combustion of hydrogen with oxygen produces water vapour as its only product. Although nitrogen oxides, known as NOx, can be produced, hydrogen internal combustion generates little or no CO, CO2, SO2, HC, or PM emissions.
Depending on how the fuel is metered, the maximum output for a hydrogen engine can be either 15% higher or 15% less than that of gasoline if a stoichiometric air/fuel ratio is used. Since one of the reasons for using hydrogen is low exhaust emissions, hydrogen engines are not normally designed to run at a stoichiometric air/fuel ratio.
Typically hydrogen engines are designed to use about twice as much air as theoretically required for complete combustion. At this air/fuel ratio, the formation of NOx is reduced to near zero. To make up for the power loss, hydrogen engines are usually larger than gasoline engines.
Design wise, the main differences between a hydrogen ICE and a traditional gasoline engine include hardened valves and valve seats, stronger connecting rods, fuel injectors designed for a gas instead of a liquid, larger crankshaft damper, stronger head gasket material, modified intake manifold, positive pressure supercharger, and a high temperature engine oil.
All modifications would amount to about 1.5x the current cost of a gasoline engine, which is cost prohibitive, both the upfront cost and O&M.
Enter the hydrogen rotary internal combustion engine – simple, compact, light, highly efficient and powerful, and relatively quiet.
Efficiency of 60% and even greater was achieved and replicated in our prototypes testing, as the engine design tended to run cooler than conventional piston engines and thus could reduce concerns over NOx. The rotary engine is also compact, resulting in about 20% less volume for the same output parameters.
The game stopper would be the impracticality of storing enough hydrogen to get meaningful range. As storing hydrogen in a car still remains a hurdle, Class 8 trucks, tractor-trailer rigs and the shipping industry have expressed high interest for our Hydrogen ICE.
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