Toyota has always chosen a different path in its quest for cleaner and more sustainable transportation. While it is true that the Japanese automaker is aggressively investigating alternative energy sources and is working on some intriguing electric vehicles for the future, a recent development with ammonia engines may reverse the tide of the EV revolution. 

The company will research these revolutionary EV replacements in partnership with China’s GAC Group. At first, this is a novel approach to researching alternative technologies outside of traditional ICE systems without making the complete switch to battery electric vehicles (BEVs). However, some questions and skepticism were raised due to the use of this as a fuel in automobile applications.

A recent press release from GAC claimed that their prototype ammonia engine is a 2.0-liter four-cylinder with 161 horsepower (163 PS) and that it does not seem to use forced induction. What makes this powerplant stand out is not that it is a high displacement engine, but rather that it emits 90% less carbon dioxide than an engine that runs on fossil fuels and has almost the same capacity and power.

What is an ammonia engine?

An ammonia engine consists of one nitrogen atom and three hydrogen atoms and uses ammonia as its major fuel source. This kind of fuel is highly unusual among internal combustion engines. The absence of carbon atoms guarantees that there are no carbon dioxide emissions during burning, which makes ammonia engines an environmentally friendly alternative to fossil fuels.

Currently, there are two main types of ammonia engines. One is known as the spark-ignition engine, and the other is the compression-ignition engine. 

Spark-ignition engines 

Since a spark is used to ignite the fuel-air mixture in these engines, they are comparable to gasoline engines.

Compression-ignition engines

Contrary to spark-ignition engines, these engines use compression to increase the fuel-air mixture’s temperature to the point of spontaneous ignition.

Approaches to take advantage of ammonia engines power

Ammonia engines can operate efficiently in several ways, including:

• Pure Ammonia Approach: in this approach, ammonia serves as the main fuel and is burned using cutting-edge technologies.
• Breakdown Approach: as demonstrated by startups like Amgoy, this approach can break down ammonia into hydrogen and nitrogen. As a result, the former power of the fuel cell will generate electricity. 
• Combination Approach: this refers to different strategies or methods that utilize ammonia in a combined or integrated manner. For example, MAN Energy Solutions blends ammonia with fuels like diesel or gas, facilitating sustained combustion.

Because it produces almost no CO2 emissions during combustion, ammonia is a fuel with the potential to be completely emission-free. However, engines that run on ammonia do release exhaust gases, which include unburned ammonia, nitrogen oxides (NOx), and nitrous oxide (N2O), none of which are very healthy.

The journey of ammonia engines just began

Ammonia boasts a high energy density, an essential feature for efficient energy storage and transportation. This makes it suitable for critical sectors like transportation and power generation. The 2.0-liter ammonia engines are capable of delivering 161 horsepower and have the potential to cut carbon emissions by almost 90%.

However, the journey will face significant challenges that automakers will urgently need to address to make it a plausible option for the EV market. Liquid ammonia has so many unfavorable aspects and warning signs that even Porsche e-fuels, which presently run about $45 per gallon (10 euros per liter), make better economic sense.

In addition to being extremely corrosive and dangerous, liquid ammonia releases a significant amount of nitrogen into the environment upon combustion. These reasons may render it unfeasible as an e-fuel substitute. Nevertheless, GAC and Toyota rely confidently on their engineers, know-how, and technology to overcome all possible challenges.