How the world’s most widely produced chemical could become clean energy’s global currency
Hydrogen is widely described as the fuel of the future, but it has a problem: it’s extremely difficult to move around. The lightest element in the universe, hydrogen requires either enormous pressure, cryogenic temperatures approaching –253°C, or expensive specialized infrastructure to transport economically. Ammonia — the simple compound of nitrogen and hydrogen (NH₃) — sidesteps most of these problems, and is attracting serious attention as a hydrogen carrier, a direct fuel, and an energy storage medium.
Ammonia’s Existing Infrastructure
Ammonia is not an exotic chemical. With roughly 180 million metric tons produced annually — primarily for nitrogen fertilizers — it already has the world’s second-largest chemical transport and storage infrastructure after oil. Ammonia can be liquefied at –33°C or 8 atmospheres of pressure, conditions that existing refrigerated chemical tankers and storage facilities already handle routinely. Pipelines, tanks, and port facilities for ammonia exist on every continent. This infrastructure inheritance is a massive economic advantage over pure hydrogen, which would require entirely new distribution systems.
Green Ammonia: The Clean Version
Conventional ammonia is synthesized via the Haber-Bosch process, combining nitrogen from air with hydrogen derived from natural gas — making it a significant source of CO₂ emissions (about 1.4% of global emissions). Green ammonia replaces the fossil-fuel-derived hydrogen with green hydrogen from electrolysis, powered by renewable electricity. The rest of the Haber-Bosch process remains the same. The result is ammonia produced with near-zero carbon emissions. Several green ammonia projects have reached final investment decision globally, and the technology’s readiness level is high — electrolysis and Haber-Bosch are both well-understood processes.
Ammonia as a Fuel
Beyond serving as a hydrogen carrier, ammonia can be burned directly as fuel. Japan has been the most aggressive pioneer of this approach. JERA, Japan’s largest electricity generator, has demonstrated 20% ammonia co-firing with coal at a commercial power plant, with a goal of 50% co-firing by the early 2030s as a transition strategy for decarbonizing coal power. The International Maritime Organization’s emissions targets have made ammonia a leading candidate for zero-carbon shipping fuel — major shipping companies including Maersk and NYK are developing ammonia-fueled vessels. Ammonia’s energy density (3,000 Wh/L versus ~2,400 Wh/L for liquid hydrogen) and established bunkering infrastructure make it more practical than hydrogen for long-distance ocean shipping.
The Cracking Challenge
When ammonia is used as a hydrogen carrier rather than a direct fuel, it must be ‘cracked’ back to hydrogen and nitrogen before use. The thermal decomposition of ammonia (NH₃ → N₂ + H₂) requires temperatures of 400–600°C and a catalyst. This adds energy cost and complexity to the system. Efficient, low-temperature ammonia cracking catalysts are an active area of research, with breakthroughs in ruthenium and iron-based catalysts improving energy efficiency. Some researchers are exploring direct ammonia fuel cells that convert ammonia to electricity without a separate cracking step.
Regional Strategies
Japan and South Korea, which have limited domestic renewable resources and depend heavily on energy imports, are developing large-scale ammonia import strategies. Japan’s Green Innovation Fund supports multiple green ammonia production projects in Australia, the Middle East, and North Africa — regions with abundant solar and wind resources — with the ammonia shipped to Japan for power generation and industrial use. The EU’s REPowerEU plan includes ammonia imports as part of its clean hydrogen supply strategy.
Princeton University’s ARPA-E-funded project is developing an integrated electrolysis and plasma catalytic ammonia synthesis system that could combine hydrogen production and ammonia synthesis in a single step using renewable electricity, potentially eliminating several processing stages. Ammonia is not a perfect solution — it is toxic, requires careful handling, and has lower combustion efficiency than hydrogen — but its existing infrastructure, established safety protocols, and versatility make it arguably the most practical near-term vector for intercontinental clean energy trade.