What role could ammonia fuel play in decarbonisation?

If it’s been given any thought, ammonia has featured in discussion about decarbonisation only as a storage form of hydrogen. However, ammonia offers certain advantages over hydrogen that could revolutionise energy storage, transport, and use. 

Ammonia, a simple molecule composed of nitrogen and hydrogen, has been a cornerstone of the chemical industry for decades. Today, it is being reimagined as an energy carrier that could solve many of the practical challenges associated with hydrogen. Hydrogen, despite its clean-burning credentials, is notoriously difficult to store and transport. It requires cryogenic temperatures below -253°C or high-pressure tanks, making it expensive and logistically complex to handle. Ammonia, by contrast, can be stored as a liquid under far milder conditions, requiring only modest pressurization or refrigeration. This fundamental difference gives ammonia a distinct advantage in terms of practicality and cost-effectiveness. 

Even more compelling is the fact that ammonia benefits from an established global infrastructure. The world already produces more than 200 million metric tons of ammonia annually, primarily for agricultural fertilizer. This vast network of production plants, pipelines, and transport systems can be adapted for energy purposes, dramatically lowering the barriers to widespread adoption. By leveraging this existing infrastructure, ammonia avoids many of the capital-intensive challenges that hydrogen faces, allowing it to emerge as a cost-effective and scalable solution. 

When used in fuel cells, ammonia offers additional advantages. Unlike fossil fuels, ammonia is carbon-free and emits no carbon dioxide when consumed. In a fuel cell, it produces nitrogen and water as byproducts, aligning perfectly with global efforts to decarbonize energy systems. Furthermore, ammonia can also act as a carrier for hydrogen. It can be broken down—or “cracked”—into hydrogen and nitrogen, enabling its use in traditional hydrogen fuel cells. This dual functionality allows ammonia to complement and enhance the hydrogen economy rather than compete with it, bridging the gap between current hydrogen technologies and the logistical realities of global energy needs. 

The technology behind ammonia fuel cells is advancing rapidly. In direct ammonia fuel cells, ammonia is oxidized at the anode to generate electricity. These systems often rely on high-temperature solid oxide fuel cells, which efficiently decompose ammonia into its constituent elements for electrochemical conversion. Another approach involves using ammonia as a hydrogen source. In this setup, ammonia is first catalytically converted into hydrogen and nitrogen, with the hydrogen then powering a standard hydrogen fuel cell. Both methods are promising, though they face technical challenges such as optimizing catalysts, improving system efficiencies, and mitigating potential emissions of nitrogen oxides (NOₓ). 

Ammonia’s advantages extend beyond its practicality and environmental benefits. Its potential for large-scale energy storage and transport could transform global energy systems. Regions with abundant renewable energy resources, such as solar and wind, could produce “green ammonia” by synthesizing it from electrolytic hydrogen and atmospheric nitrogen. This ammonia could then be shipped to energy-poor regions, creating a global renewable energy trade network. This model not only addresses the intermittency of renewables but also enables energy export from renewable-rich regions, such as the Middle East or North Africa, to high-demand areas like Europe or Asia. 

Despite its promise, ammonia is not without challenges. Its production is currently dominated by the energy-intensive Haber-Bosch process, which relies heavily on fossil fuels. Transitioning to green ammonia production using renewable electricity is essential to ensuring its role as a truly sustainable energy carrier. Moreover, ammonia’s toxicity and the potential for NOₓ emissions during combustion require robust safety protocols and emission control technologies. Advances in catalyst design and system engineering are also critical to improving the efficiency and scalability of ammonia fuel cells. 

Nevertheless, ammonia’s potential as a clean energy carrier is undeniable. It addresses many of the limitations of hydrogen while offering a practical, scalable solution for decarbonizing energy systems. By enabling efficient energy storage, transport, and utilization, ammonia fuel cells could reshape the way we think about renewable energy. As investments in ammonia technology grow and research continues to tackle its remaining challenges, it is becoming increasingly clear that ammonia is more than a complementary player in the hydrogen economy—it may well become a cornerstone of the clean energy future.