Ammonia has been proposed as a clean fuel for ships, airliners, trucks and trains, but China’s GAC believes it could also have a future in passenger cars. 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% diesel, 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.
GAC will face other challenges if it truly wants to bring ammonia engines to the auto world – not the least of which will be a complete lack of fueling infrastructure, although this might give the industry breathing room to create a fueling system that’ll keep humans safe from this highly toxic substance.
But there’s also its pretty much unavoidable tendency to create high levels of NOx emissions – and in the case of diesel-adjacent compression style engines, the problem of having unburned ammonia coming out of the tailpipe as well. And of course the fact that most of today’s ammonia is made using the high-emissions haber-bosch process.
Still, we’ll be interested to see where this concept goes, if it makes it past a simple tech day presentation. Which it may not.
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