It's built a combustion engine to test the theory, capable of reducing emissions by around 90%.

Ammonia (NH3) carries hydrogen better than hydrogen carries hydrogen, in some regards. It's easier to handle, since it's liquid at ambient temperatures, and it thus doesn't require energy-hungry compression or cryogenic liquefaction gear.

You can make it cleanly – although that's not how the overwhelming majority of it is made today. It's also highly caustic, and an "extremely hazardous substance" to humans and many animals alike. So it's got plenty of cons along with its pros – not that gasoline or diesel don't have their own issues.

While many green ammonia vehicle projects aim to "crack" the ammonia back into hydrogen, release the nitrogen back into the air and run a fuel cell to create electric power, others use it in modified combustion engines. And that's what we're looking at today.

Guzngzhou Automotive Group Co. (GAC) announced at a recent Tech Day presentation that it had developed a 2.0-liter engine capable of burning liquid ammonia safely and efficiently. According to Bloomberg, GAC claims a 120 kW (161 hp) peak power output, and a 90% reduction in carbon emissions compared to conventional fuels.

Is it a "world first?" Eh, maybe. Researchers at the Korean Institute for Energy Research built and tested a car called AmVeh a decade ago, which ran on 70% ammonia, 30% gasoline. It cut down carbon emissions by 70%, and at the time, the AmVeh team was definitely focused on the idea of a fully ammonia-fueled engine.

Given that the GAC engine still appears to create some carbon dioxide, there's possibly some other fuel source going in there as well. That'd make sense, as the low propagation speed of flame in ammonia tends to make engines struggle at high RPMs or low engine loads.