AN INDUSTRIAL PLANT, NOT A POWER STATION
89.6% CAPACITY FACTOR, ON A 416 MW BATTERY
Industrial Facility
A green ammonia plant is often described as renewable generation with an electrolyser attached. That description is wrong, and it explains why so many announced projects fail to reach a final investment decision.
An ammonia plant is an industrial facility, and its economics are governed by one number above all others: the capacity factor of the Haber-Bosch synthesis loop.
Why that one number decides everything
A gas-fired ammonia plant’s cost is dominated by feedstock, so its economics track the gas price. A green plant has almost no fuel cost. Its cost is the capital sunk into the electrolyser, the synthesis loop, the hydrogen chain and the generation behind them, divided by the tonnes it produces – and tonnes produced scale almost directly with capacity factor.
The consequence is stark. A plant held at 50% carries close to double the capital cost per tonne of the same plant held near 90%, because the same fixed assets are spread over little more than half the output. For green ammonia, capacity factor is the master variable in a way it never is for gas.
The Boolathana platform reaches an 89.6% synthesis-loop capacity factor.
That sits inside the 88 to 93% availability band of conventional gas-fired ammonia plants. Most renewable-powered concepts reach 50 to 60%, and the few that push higher do so by spending heavily — oversized batteries, large hydrogen storage, grid firming, or gas-fired backup.
The number, and its benchmark
Boolathana reaches it on a 416 MW battery and an 800-tonne hydrogen store. Reaching a high capacity factor is difficult. Reaching it with almost no storage is what makes the design work.
The first reason - the resource is firm before storage is added
Wind at Boolathana is night-dominant. It averages roughly 1,740 MW overnight against about 920 MW at midday – nearly twice as high – and around two-thirds of its energy arrives in hours when solar is producing nothing – being 49.1% of all hours. Wind exceeds the electrolyser’s minimum stable load in close to 89% of night hours, which means on the great majority of nights the plant is fed by generation, not by stored energy.
The two resources are anti-correlated at −0.24. The combined profile never approaches zero, because wind alone holds the overnight floor. This is set out in full on The Resource.
Storage and dispatch can refine the shape of an energy resource. They cannot affordably manufacture a capacity factor the resource does not support. The resource sets the ceiling; the plant design reaches up to it.
The second reason - the electrolyser is deliberately oversized
The instinct is to match electrolyser capacity to renewable capacity. Running the full hourly dispatch across a grid of sizes shows a slightly larger electrolyser produces a materially better outcome.
When generation peaks, a generation-matched electrolyser cannot absorb the surplus and it is spilled. A larger one absorbs those peaks and turns energy that would have been spilled into hydrogen, and then into ammonia. Moving from a matched 2,000 MW configuration to the selected 2,400 MW brings curtailment down from around 20% to and lifts annual output about 10%, to 1,767 kilotonnes.
The cost of that trade is a lower electrolyser capacity factor – 75.2% rather than the low 80s a tighter match would show. That is productive reserve, not idle capital: the extra capacity earns its keep in additional ammonia and less waste.
The optimum is a flat basin rather than a knife edge. The design does not depend on hitting a single sizing point.
Storage sized to its job
No gas in the base case
Across 61,368 hours of record, the longest continuous zero-generation event was twelve hours – a single mid-winter overnight period.
On warm hold, with the synthesis loop kept at temperature but not producing, the battery alone sustains it for 21.4 hours.
The hydrogen store independently provides 20.2 hours of synthesis-loop feed. The worst observed event is covered with margin, from two independent buffers. Because the synthesis loop turns down to 30% of nameplate, effective endurance during a managed lull extends further, and the plant is never forced toward shutdown.
A combustion fleet sized to keep the process load running would add capital and maintenance, consume saleable ammonia or gas as fuel, and run for a negligible fraction of the year against an event the storage already covers. It is excluded from the base dispatch case by design.
This concerns process-load backup only. The plant carries the essential-services backup any industrial facility requires – black-start capability, meaning enough generation to restart the plant from a complete shutdown, uninterruptible power for controls and safety systems, and firewater supply.. Those are retained.
Against a conventional plant
The reference configuration
Generation
2,779 MW wind – 397 × Envision EN-220/7.0 – 53.3% capacity factor
2,225 MW solar – 36.4% capacity factor
Total installed approximately 5,004 MW, delivering 19.46 TWh annually net
Conversion
2,400 MW alkaline electrolysis
5,400 tonne-per-day Haber-Bosch train
Storage
416 MW / 1,664 MWh battery
800 tonnes hydrogen at 65 bar
Output
314.9 kt hydrogen a year
1,767 kt ammonia a year
Basis
Hourly dispatch modelled across 61,368 steps, 2016 to 2022
What is proven, and what is not
The dispatch outputs – 89.6% synthesis-loop capacity factor, 75.2% electrolyser capacity factor, 9.3% curtailment – are proven across the full hourly model, calibrated to the validated base case. Plant and storage sizing are dispatch-proven and carry forward to FEED engineering.
Three items remain to be confirmed.
1. The electrolyser’s specific energy consumption of 50.2 kWh per kilogram of hydrogen awaits vendor confirmation.
2. The Haber-Bosch minimum stable load of 30% is a design assumption carried to vendor and FEED confirmation. It is the assumption that enables genset-free dispatch.
3. Absolute annual output will be confirmed at FEED, though the sizing that produces it is robust.
GGE states what its cost figures include — generation, firming, water, export and the synthesis process — rather than quoting a favourable subset.
Detailed cost modelling is available to qualified investors under NDA.
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