LiquidPiston, Inc., developer of advanced rotary diesel and multi-fuel internal combustion engines, has successfully run its X-Engine next-generation rotary engine on hydrogen gas. This is the sixth fuel variation that has been shown to power the X-Engine along with gasoline, propane, kerosene, diesel, and jet A fuel.

To demonstrate the viability of hydrogen fuel powering the X-Engine, the LiquidPiston team modified its 4.5 lb X-Engine (core) to run on hydrogen. The engine was then installed in a hybrid-electric configuration on a go-kart, which was originally powered by a 39-pound gasoline engine.

The hybrid approach combines the benefits of hydrogen power with the benefits of electric power, and can enable regenerative braking, where the simple act of braking works to recharge the go-kart’s battery, allowing for longer travel times between refueling stops.

The developmental X-Engine was initially tested at the company’s on-site dyno testing facility.

Hydrogen can be challenging for piston engines; the ignition energy of hydrogen is extremely low, and any hot spots cause premature ignition of the fuel. The hydrogen combustion process is also significantly faster than that of traditional fuels. The X-Engine offers a pathway to address these challenges in a package that is more powerful and lower cost than fuel cells, the company says.