Ammonia Instead of Gasoline? Chinese Automaker GAC Suggests It

From the November 2023 issue of Car and Driver.

The auto industry continues to look for new ways to reduce carbon emissions. Though most manufacturers are cutting carbon by developing battery-electric vehicles, others continue to tinker with alternative fuels, such as hydrogen and carbon-free or carbon-neutral synthetics. The Chinese automaker GAC, in partnership with Toyota, is now adding ammonia to this mix.

Most of us have used ammonia—in a highly diluted form—as a pungent yet effective window cleaner. But pure ammonia will burn. The chemical is a compound of nitrogen and hydrogen (hence its chemical formula, NH3), so there are no carbon emissions to worry about.

Why hasn’t ammonia received much attention in automotive contexts? For starters, it’s not a great fuel. Ammonia is difficult to ignite at low temperatures, combusts over a narrow air-to-fuel ratio, and, among other things, can be prone to detonation. It boils at a chilly −28 degrees Fahrenheit and needs around 150 psi of pressure to remain liquid at the temperatures in which cars typically operate. Oh, and it’s toxic.

We already produce around 200 million tons of ammonia each year (most of which goes into fertilizer). The process to make the majority of it, which requires first stripping hydrogen from natural gas, releases over twice as much carbon dioxide as it creates ammonia. Using electrolysis to extract hydrogen from water avoids those emissions, but it’s highly energy intensive, not to mention expensive.

GAC’s Ammonia-Powered Engine

GAC is mum on the details of its ammonia-powered engine, though the company claims the 2.0-liter unit produces 161 horsepower and nets a 90 percent reduction in carbon emissions. Why not 100 percent? We wager that GAC’s engine relies on an ammonia blend to control combustion. For instance, achieving a 90 percent reduction in carbon is possible with an ammonia mix that’s 20 percent gasoline. Going such a route means developing a dual-fuel engine with very precise controls for the injection of the ammonia and the other fuel.

Ammonia may not emit carbon, but combusting it releases oxides of nitrogen, a primary component of photochemical smog. Of course, adding a catalyst to the exhaust reduces—but does not completely eliminate—the harmful gases ammonia produces.

Deriving ammonia from natural gas has negative environmental impacts too, and until cleaner production methods prove cost effective, this dirty but inexpensive approach will surely remain the industry standard. Factor in the toxic nature and compressed-storage needs of this inorganic compound (and don’t get us started on the complex dual-fuel system that GAC’s ammonia-burning engine seemingly requires), and we suspect ammonia’s future as a power source for passenger vehicles will, at best, mirror that of compressed natural gas. But it’s great for cleaning windows.