Green Ammonia and the Fertiliser Supply Chain: What Hydroponic Growers Should Know

Green ammonia is often discussed as a solution for decarbonising shipping and power generation. But for anyone growing hydroponically, the more immediate question is simpler: what does it mean for the fertilisers we buy?

Almost every nitrogen-based nutrient solution, whether you’re running a Kratky lettuce setup or a full recirculating NFT system, contains ammonia-derived nitrogen. That nitrogen currently comes from one of the most carbon-intensive industrial processes on the planet. Green ammonia would change that, and the transition is closer than most growers realise.

What Is Green Ammonia?

Ammonia (NH₃) is a compound of nitrogen and hydrogen. Conventional “grey” ammonia is produced by reacting hydrogen, stripped from natural gas via steam methane reforming, with nitrogen extracted from air. This process, called the Haber-Bosch process, accounts for approximately 1–2% of global CO₂ emissions annually, according to the Royal Society’s 2020 briefing on green ammonia.

Green ammonia uses the same Haber-Bosch synthesis step, but replaces the fossil-fuel-derived hydrogen with hydrogen produced via electrolysis, splitting water into hydrogen and oxygen using electricity from renewable sources (wind, solar, or hydro). The result is chemically identical ammonia with a near-zero carbon footprint.

The three-step process:

1. Electrolysis: Renewable electricity splits water (H₂O) into hydrogen (H₂) and oxygen (O₂).
2. Nitrogen fixation: Nitrogen (N₂) is extracted from the air using an air separation unit.
3. Ammonia synthesis: Hydrogen and nitrogen are combined under high pressure and temperature via Haber-Bosch to form NH₃.

The chemistry isn’t new. The energy source is.

Why the Fertiliser Industry Is Watching This Closely

Ammonia is the precursor to virtually every nitrogen fertiliser: urea, ammonium nitrate, ammonium sulphate, calcium ammonium nitrate. When you buy a bottle of hydroponic nutrients labelled “nitrogen 8%”, a significant portion of that nitrogen originated as ammonia produced from natural gas.

Global ammonia production is around 185 million tonnes per year, with roughly 80% going directly into fertiliser. The IEA’s Ammonia Technology Roadmap (2021) estimates that decarbonising ammonia production alone could eliminate over 450 million tonnes of CO₂ annually, comparable to the entire aviation sector.

For commercial hydroponic growers, this matters for two reasons:

• Carbon accounting: Retailers, restaurants, and food brands are increasingly demanding supply chain emissions data. Nutrients produced from green ammonia would reduce the embodied carbon of your crop.
• Price trajectory: Green ammonia currently costs 2–3× more than grey ammonia to produce, primarily because of electrolyser costs and renewable electricity pricing. But the IEA projects cost parity with grey ammonia in favourable renewable energy markets by the early 2030s. That means greener, and eventually cost-competitive, nutrient inputs for hydroponic operations.

The largest near-term driver isn’t idealism; it’s regulation. The EU’s Carbon Border Adjustment Mechanism (CBAM), which began its transitional phase in October 2023, will apply full carbon pricing to imported fertilisers by 2026. This creates direct financial pressure on fertiliser producers to cut emissions or pay a carbon premium, which will eventually reach growers through input costs.

To understand why nitrogen management matters at the plant level, see our guide on choosing the best hydroponic nutrients for your garden and optimal pH and EC values for hydroponic herbs and plants.

Where Green Ammonia Is Being Deployed Right Now

Green ammonia is not hypothetical. Several large-scale projects are operational or under construction:

• NEOM (Saudi Arabia): ACWA Power and Air Products are building a 4 GW renewable energy plant to produce 650 tonnes of green ammonia per day, targeting export to Europe and Asia. Production began in limited capacity in late 2024.
• Yara International (Norway): The world’s largest fertiliser producer has announced plans to decarbonise production at its Porsgrunn facility using offshore wind-powered electrolysis, with a target of producing 500,000 tonnes of low-carbon ammonia annually by 2030.
• Shipping sector: MAN Energy Solutions and Wärtsilä have both certified ammonia-capable marine engines. Maersk and other major carriers have ammonia-powered vessels on order, with delivery scheduled between 2025 and 2027.

The shipping industry’s adoption matters for growers indirectly: it creates demand that justifies green ammonia infrastructure, which in turn lowers costs for the fertiliser-grade product.

The Honest Challenges

Green ammonia faces real obstacles that haven’t been resolved by optimism or press releases.

Cost is the primary barrier. Producing a tonne of green ammonia currently costs $600–$1,200 depending on the renewable energy source and location, compared to $200–$400 for grey ammonia (BloombergNEF, 2023). Electrolyser manufacturing capacity is constrained, and scaling it quickly enough to meet decarbonisation targets requires capital deployment that is only just beginning.

Storage and handling are genuinely difficult. Ammonia is toxic, corrosive, and requires pressurisation or refrigeration for storage. Existing port infrastructure for ammonia is limited. Unlike hydrogen, ammonia has established handling protocols from the fertiliser trade, which gives it an advantage, but the safety requirements remain more complex than fossil fuels.

The green electricity bottleneck. An electrolyser is only as green as the electricity feeding it. In regions where the grid is still coal-heavy, “green” ammonia can have a higher carbon footprint than the grey alternative if accounting is done carefully. Additionality, ensuring that renewable electricity genuinely displaces fossil generation rather than just being paper-purchased, is an unresolved policy question.

What This Means If You’re Running a Hydroponic Operation

In practical terms, nothing changes today. Your nutrient suppliers are not yet offering certified green-ammonia-derived products at scale. But three things are worth watching:

1. Look for low-carbon nutrient certifications emerging over the next 2–3 years. Yara and a handful of European producers are already selling “low-carbon” ammonium nitrate under specific agreements. As supply grows, retail hydroponic nutrients will follow.
2. Watch input prices in 2026–2027. CBAM’s full implementation will affect import pricing on nitrogen fertilisers entering the EU. If you’re in Europe or sourcing from European distributors, expect this to flow through to nutrient prices.
3. The efficiency argument for hydroponics holds regardless. Hydroponic systems already use 90% less water and deliver nitrogen far more efficiently than soil growing, meaning less ammonia is wasted to leaching or volatilisation. That efficiency advantage becomes more valuable as nitrogen costs rise. See our overview of hydroponics vs. traditional gardening for the full comparison.

FAQ

What is green ammonia? Green ammonia is chemically identical to conventional ammonia (NH₃), but produced using renewable electricity rather than fossil fuels. The hydrogen used in its synthesis comes from water electrolysis rather than steam methane reforming of natural gas, eliminating the CO₂ emissions associated with conventional production.

How is green ammonia made? Renewable electricity (wind, solar, or hydro) powers an electrolyser that splits water into hydrogen and oxygen. The hydrogen is then combined with nitrogen extracted from air using the Haber-Bosch process, producing ammonia without carbon emissions.

How does green ammonia differ from blue or grey ammonia? Grey ammonia uses fossil fuels with no carbon capture. Blue ammonia also uses fossil fuels but captures and stores the resulting CO₂ (carbon capture and storage). Green ammonia uses renewable energy and produces no CO₂ in the first place. Green has the lowest lifecycle emissions; grey has the highest.

When will green ammonia affect fertiliser prices? The IEA projects cost parity with grey ammonia is possible in markets with cheap renewable electricity by the early 2030s. Regulatory pressure (particularly CBAM in the EU) may accelerate the timeline for low-carbon product premiums appearing in retail fertiliser pricing before then.

Does green ammonia matter for home hydroponic growers? Not immediately. But it’s worth understanding the supply chain your nutrients come from. As low-carbon certification programmes develop, growers who care about embodied carbon in their inputs will have more options, and potentially access to marketing differentiation if selling their produce commercially.