Chinese automobile manufacturer GAC is walking where others fear to tread and heading in an unexpected fuel direction. The Guangzhou Automobile Group wants to save the internal combustion engine, and its strategy is based on burning ammonia. People are somewhat taken aback by the decision because ammonia is highly toxic, and releasing it for public use comes with risks.
Ammonia is toxic, but GAC has faith it’s going to save the ICE
Using ammonia as a fuel is by no means unheard of, as it’s proving useful in the heavy-duty trucking and shipping industries. It has a high energy density and there’s already an existing supply chain in place due to ammonia’s extensive worldwide use as a fertilizer. It’s easier to store than hydrogen because it maintains its liquid state at relatively low pressure.
The problem is that ammonia is highly toxic, making it impractical for the public. Any system that uses ammonia in a standard vehicle will have to address not only this issue but also consider the harmful nitrous oxide (NOx) emissions generated by burning ammonia.
During its annual technology showcase, GAC developers expressed their confidence that they’ve built an effective, efficient internal combustion engine for regular cars. This comes at a time when most of the auto industry is looking to battery-electric or fuel cell powertrains in the drive to move away from carbon-emitting fossil fuels.
The model that was showcased at GAC’s technology expo was a 2.0-liter I-4 that produces 161 hp. GAC is committed to climate goals and believes it’s found a way to reduce emissions by 90% compared to gas-powered cars.
Can the challenges of ammonia be overcome to make it a viable option for cars?
Although GAC is showing full confidence in its new technology, it’s highly unlikely that we’ll see the general public having anything to do with ammonia in their day-to-day lives. There are two significant problems with using ammonia as a fuel, especially for passenger vehicles.
Ammonia is highly toxic
Ammonia is a dangerously toxic solvent that’s capable of dissolving alkali metals. Exposure to ammonia as either a gas or a liquid is potentially fatal to humans and animals, and according to the EPA (Environmental Protection Agency), it’s the leading cause of fish deaths in the United States.
The reason why ammonia is considered a diesel fuel alternative for the heavy-duty trucking and shipping sectors is because these are already experienced with and infrastructurally set up for the handling, transportation, and distribution of toxic substances.
Ammonia is tricky to use in ICE engines
Ammonia has a high octane rating of 120, a flash point of 270°F, and an autoignition temperature of 1,203.8°F. In contrast, gasoline has an energy density of 33.7 kWh/gallon, a flashpoint of -9°F, an autoignition temperature of 1,135°F to 1,550°F, and an octane level between 87 and 92.
Ammonia is emissions-free, but there’s a nitrogen issue
There are some features of ammonia that make it look promising: when it burns, it’s carbon-free, produces no CO₂, zero hydrocarbons, and zero soot. Unfortunately, when burned in an engine without a high compression ratio or boost, it releases a high amount of nitrogen. This results in ammonia and ozone being created in the atmosphere, which has the potential to cause acid rain and affect people’s breathing.
The challenges of ammonia, including toxicity and infrastructure, mean it’s unlikely that it will be extensively used as a fuel for passenger cars. However, it has potential in hydrogen production, which is a more practical use of ammonia in the context of renewable energy.
In more viable transportation development of ammonia, MAN Energy Solutions has revealed a dual-fuel methanol model that can also run on ammonia.