Hydrogen has to be stored at -253 ºC as a liquid, or at pressures of around 700 bar as a gas. By contrast, liquid NH3 can be stored at a temperature of -33 ºC at standard pressure, or at +20 ºC at 9 bar. That makes storing and transporting it far easier and more straightforward.
The Amogy system consist of a standard liquid-storage tank and highly efficient ammonia-cracking modules integrated into a hybrid fuel cell system, which can provide consistent primary power for several hours from a fuel tank.
Ammonia cracking occurs at high temperatures, typically around 800 ºC, but integrating the cracking module with the fuel cell provides the power for heating the cracker as well as powering the motors in the tractor.
The ammonia is fed into the cracking module, where it is split into nitrogen and hydrogen; 75% of the gas consists of hydrogen. A small amount of NH3 (100 ppm) is not converted and left over in the gas stream.
The company is planning a demonstration of Class 8 trucks and shipping vessels with a 1 MW system in the next year using the technology. Ammonia is already a globally traded commodity, with 20 million tons of the chemical shipped each year among almost 200 ports. This existing transportation and storage infrastructure is key for electric ships.
Researchers in Germany are also planning a demonstration of an ammonia-based fuel cell system for shipping by the end of next year.
This system, developed at Fraunhofer IMM, uses a passive catalytic converter to reduce the 12% of the hydrogen and residual NH3 that leaves the fuel cell unused. The Fraunhofer design uses a corrugated metal foil coated with a powdered layer of catalytic particles that contain platinum to trigger a chemical reaction with air so that the only end-products are water and nitrogen.
This technology will be used in the Viking Energy, a supply vessel owned by the Norwegian shipping company Eidesvik.
