Green Ammonia Reactor: Haber-Bosch on Renewable Hydrogen

Reactor Conditions

Temperature 450 °C

Pressure 200 atm

Renewable electrolyzer power 60%

Catalyst activity 100%

Live Readouts

Equilibrium conversion

—%

Current conversion

—%

Kp(T)

—

H2 feed rate

— mol/s

Est. CO2 avoided

— kg/day

NH3 in mix

—%

N2 (feed nitrogen) H2 (renewable hydrogen) NH3 (product)

How it works

Green ammonia replaces fossil-derived hydrogen with hydrogen from water electrolysis powered by wind or solar, then runs the same catalytic Haber-Bosch reaction used industrially since 1913:

N2(g) + 3H2(g) ⇌ 2NH3(g)      ΔH ≈ -92.4 kJ/mol (exothermic)

The reaction is reversible, so the reactor never fully converts its feed — it approaches a temperature- and pressure-dependent equilibrium. The equilibrium constant Kp is estimated with the classic Gillespie-Beattie correlation (T in kelvin):

log10(Kp) = -2.691122·log10(T) - 5.519265e-5·T
            + 1.848863e-7·T² + 2001.6/T + 2.6899

Starting from a stoichiometric 1:3 feed of N2:H2 and letting x be the fraction of N2 converted, the mole fractions are y_N2=(1-x)/(4-2x), y_H2=3(1-x)/(4-2x), y_NH3=2x/(4-2x). At equilibrium, with all species treated as ideal gases at total pressure P (atm):

Kp = y_NH3² / (y_N2·y_H2³) · P⁻²

The simulator solves this equation for x numerically every time you move a slider. Because the forward reaction loses 2 moles of gas per mole of N2 reacted, Le Chatelier's principle means higher pressure always pushes the equilibrium toward more NH3, while higher temperature pushes it back toward N2 + H2 (the reaction is exothermic) even though hotter catalyst beds react faster. Real plants trade these off, running around 400-500 °C and 150-300 atm.

The current conversion readout relaxes toward the equilibrium value with a rate set by catalyst activity and by how steadily the electrolyzer can supply H2 — low renewable power availability (cloudy, calm days) starves the reactor of hydrogen and slows the approach to equilibrium, which is the real operating challenge of coupling Haber-Bosch to intermittent renewables. The CO2-avoided figure is an illustrative estimate: conventional "grey" ammonia emits roughly 1.9-2.2 t CO2 per tonne of NH3 from steam-methane reforming, so we scale that figure by the renewable power fraction.

N2 + 3H2 ⇌ 2NH3

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