Green Ammonia: Decarbonising Fertiliser Production with Green Hydrogen
Introduction
Ammonia (NH₃) sits at the heart of modern agriculture. It is the starting point for nearly all synthetic nitrogen fertilisers, forming a chemical bridge between the nitrogen in the air and the food on our plates. Roughly 70% of global ammonia production is used to make fertilisers, underscoring its central role in feeding the world’s crops. [1]
Decades of agronomic data show that synthetic nitrogen fertiliser enabled dramatic increases in crop yields in the twentieth century, helping support billions of people who might otherwise have faced food scarcity. [2]
Yet, conventional ammonia is energy-intensive and overwhelmingly fossil-fuel-based; producing it emits large amounts of carbon dioxide (CO₂), making the fertiliser industry one of the most emissions-intensive in heavy industry. Direct emissions from global ammonia production are estimated at ~450 million tonnes of CO₂ per year, with total life‑cycle impacts even higher once electricity and downstream fertiliser use are included. [4]
Cutting those emissions without compromising crop nutrition has become a priority for climate‑aligned food systems. Green ammonia, made with renewable hydrogen, offers a practical and scalable pathway.
What Is Green Ammonia?
Traditional “grey” ammonia relies on hydrogen stripped from natural gas (steam methane reforming) or, in some regions, from coal gasification—both processes release CO₂.
In contrast, green ammonia is produced using green hydrogen: hydrogen generated by splitting water in electrolysers powered by renewable electricity (wind, solar, hydro, etc.). The green hydrogen is then reacted with nitrogen (from air) in the familiar Haber‑Bosch synthesis loop to form ammonia, but with little or no direct CO₂ emissions if renewable power is used throughout.
Because the resulting ammonia molecule is identical, green ammonia can be used directly to substitute for grey ammonia in fertiliser production and downstream products, making it a “drop‑in” decarbonisation route for the sector.
As a concept, it is already being implemented in practice: fertiliser producers are installing electrolysers alongside existing plants, allowing renewable hydrogen to gradually displace fossil-derived feedstock over time.
Why It Matters
Feeding the world sustainably requires addressing the hidden carbon in fertilisers. Estimates from agronomic and demographic studies converge on the conclusion that synthetic nitrogen fertilisers support roughly half of humanity—a testament to their importance in global food security.
Life-cycle analysis suggests that switching from grey to green ammonia could reduce the embedded emissions in many everyday food products. One McKinsey analysis of a representative European consumer basket found an average reduction of ~5% in product emissions simply by decarbonising the ammonia used upstream.
That is a material lever across the food value chain, especially because many other agricultural emissions are harder to abate. Meanwhile, the conventional ammonia industry’s current footprint—hundreds of millions of tonnes of CO₂ annually- makes it a “must‑tackle” sector on any credible path to net zero.
If we can produce the same fertiliser nutrients using renewable energy instead of fossil fuels, we can both safeguard yields and decarbonise a chunk of global industry in one move. [11]
How It Works (The Short Version)
All large‑scale ammonia is made via the Haber‑Bosch process, where hydrogen (H₂) and nitrogen (N₂) react under high temperature and pressure over a catalyst to form NH₃. The critical pivot point for decarbonisation is the source of hydrogen. In a green ammonia plant:
Electrolysis: Renewable electricity powers an electrolyser that splits water into hydrogen and oxygen. No fossil feedstock is required; the primary inputs are electricity and water.
Air Separation: Nitrogen is extracted from the air. (This step is common to both grey and green routes.)
Haber‑Bosch Synthesis: Green H₂ and N₂ are fed into the reactor loop to produce ammonia. If the heat and compression are also powered by clean energy, process emissions fall dramatically.
Integration / Retrofit Pathway: Existing ammonia plants can be retrofitted by adding renewable hydrogen (initially as a blend) without rebuilding the full synthesis loop, allowing progressive decarbonisation over time. [5][6]
Because the chemistry is established and global ammonia infrastructure already exists (including pipelines, storage tanks, and shipping terminals), green ammonia can scale by leveraging much of what is already built—an advantage over building entirely new supply chains from scratch.
Global Momentum: Early Projects Point the Way
A growing roster of real-world projects demonstrates that green ammonia is transitioning from concept to commercial reality, often beginning with partial substitution of renewable hydrogen before scaling up to complete conversion.
Norway (Yara Herøya): In June 2024, Yara inaugurated a 24 MW renewable hydrogen plant at Herøya Industrial Park, the largest operating facility of its kind in Europe.
The project is now producing renewable hydrogen and ammonia and has already delivered the first fertilisers made from renewable ammonia to market. Replacing natural gas feedstock at the site is expected to cut ~41,000 tonnes of CO₂ per year.
United States (CF Industries, Donaldsonville, Louisiana): CF Industries, one of the world’s largest ammonia producers, is installing a 20 MW alkaline water electrolyser (thyssenkrupp technology) to make green hydrogen that will be converted to up to ~20,000 tonnes per year of green ammonia at its massive Donaldsonville complex.
The modular design allows capacity expansion over time, creating a scalable pathway from pilot volumes to substantial low‑carbon fertiliser output.
Saudi Arabia (NEOM Green Hydrogen Company): Construction of what is set to become the world’s largest renewable ammonia facility—designed for about 1.2 million tonnes per year of green ammonia from ~4 GW of dedicated solar and wind—is reported to be ~80% complete (as of June 2025).
Commercial operations are expected to commence in 2027, with production destined for export markets that include fertiliser and zero-carbon fuel applications. [7]
Morocco (OCP Group): Phosphate and fertiliser giant OCP is advancing a suite of renewable ammonia initiatives to reduce and ultimately replace imported fossil‑based ammonia. Plans include multi-gigawatt solar and wind buildouts, as well as targeted renewable ammonia production, ranging from pilot tonnages to 1 million tonnes per year by 2027, with longer-term expansions under consideration. [12]
Zimbabwe: Electrolysis‑based ammonia is not a twenty‑first‑century novelty. Sable Chemical Industries in Kwekwe, Zimbabwe, commissioned a 290 MW alkaline electrolysis unit in 1972, powered largely by hydropower from the Kariba dam. For more than four decades the plant produced renewable hydrogen on‑site and synthesised up to ~120 000 t NH₃ per year (equivalent to 240 000 t of ammonium nitrate fertiliser), demonstrating at industrial scale that water‑electrolysis can underpin continuous Haber‑Bosch operation. [13]
Australia & Local Production Opportunities: An analysis from the Institute for Energy Economics & Financial Analysis (IEEFA) highlights ammonia production as an ideal early adopter for green hydrogen in Australia, noting over AUD 15 billion in federal support measures and the ability to inject green hydrogen into existing ammonia plants without wholesale redesign.
IEEFA concludes that with scale and policy support, green ammonia could reach cost parity with gas‑based ammonia in some regions by the early 2030s. [8]
These flagship efforts are being closely watched because they create templates—technical, financial, and regulatory—for the wider fertiliser industry. Taken together, they signal that green ammonia is no longer speculative; it is entering its commercial proving phase across multiple continents.
Challenges and the Solutions Emerging
Cost Gap: The main barrier remains cost. Electrolysers, renewable electricity and new balance‑of‑plant investments make green ammonia more expensive than incumbent grey ammonia in most markets today.
However, government incentives (tax credits, grants, low‑cost finance) plus economies of scale are already bending the curve. IEEFA analysis indicates that with current Australian policy support, green hydrogen for ammonia could become cost‑competitive with natural gas feedstock by the early 2030s in favourable locations.
The global scale-up of electrolyser manufacturing and rapidly falling renewable energy costs further strengthen the outlook.
Emissions Intensity of Today’s Fleet: Best‑available steam‑methane‑reforming ammonia still emits ~1.8 tCO₂ per tonne of ammonia; global average emissions are higher, mainly where coal is used.
Retrofitting existing plants with carbon capture and storage (CCS) technology, also known as “blue ammonia,” can quickly reduce most of those emissions and may serve as a bridge while green capacity is built.
Many large producers are pursuing dual tracks—installing electrolysers where renewable power is available and adding CCS to legacy assets elsewhere—to accelerate near‑term abatement.
Intermittent Renewables vs. Continuous Plants: Haber-Bosch units prefer steady operation, whereas wind and solar are variable. Solutions include on‑site hydrogen storage, hybrid renewable portfolios that smooth output, grid back‑up, and designing more flexible ammonia loops that can ramp safely.
Early projects (e.g., Yara Herøya) are generating operational learning that will inform larger roll‑outs.
Policy Alignment & Market Signals: Regulatory drivers are strengthening. The EU’s revised Renewable Energy Directive (RED III) requires that 42% of the hydrogen used in industry by 2030 be renewable fuels of non-biological origin (RFNBOs), rising to 60% by 2035 —a rule that directly affects ammonia producers, the single largest industrial consumers of hydrogen. [9]
In parallel, the EU’s Carbon Border Adjustment Mechanism (CBAM) will bring fertilisers under a carbon pricing regime at the border, rewarding low‑carbon imports (including green ammonia) and discouraging high‑emission products. [10] Such policies narrow the cost gap and provide revenue certainty for early movers.
Value Chain Coordination: Since fertiliser use sits at the start of long, complex food supply chains, collaboration is necessary to share the incremental costs of green products. McKinsey finds that food companies, retailers, and consumers may all need to participate in new purchasing models for low-carbon fertilisers to scale.
Encouragingly, branded green fertiliser deliveries (e.g., Yara’s first renewable batches) show that market pull is beginning.
A Fertile Future
If the industry maintains current momentum, green ammonia could shift from demonstration volumes to mainstream fertiliser feedstock over the next decade.
Scenario work by the International Energy Agency indicates that global ammonia demand is likely to increase in line with population growth and dietary changes. Still, the pathway to climate alignment depends on replacing fossil feedstocks with low‑carbon technologies (electrolysis, CCS, and emerging processes) at scale.
With supportive policy, analysts see cost parity within reach in favourable regions by the early 2030s, after which adoption could accelerate sharply. [8]
Farmers and food brands are increasingly facing pressure to document Scope 3 emissions; sourcing fertilisers made with renewable ammonia offers a clear, auditable step toward lower-carbon food supply chains.
Given ammonia’s established logistics network, green variants can integrate into existing granulation and fertiliser formulation lines—urea, nitrates, and compound fertilisers made from green ammonia perform and look the same in the field.
Most importantly, this transition allows agriculture to retain the yield benefits of synthetic nitrogen without the embedded fossil carbon. That means we can continue to nourish a growing global population—already dependent on ammonia for a significant share of its food calories—while aligning with net-zero climate goals.
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