Jülich study provides a blueprint for load-flexible production plant – and lower costs
2 June 2025
Converting ammonia production to a low-emission process is one of the major challenges in the fight against climate change. Ammonia, one of the most widely produced chemicals worldwide, is essential for the fertilizer industry and, in turn, the production of plant-based foods. However, its production is expensive and and causes high emissions. A research team from Forschungszentrum Jülich, the Technical University of Munich, and chemical company Linde Engineering has conducted a study simulating what a reactor would need to look like to produce ammonia in a cost-effective, environmentally friendly manner, i.e. based on renewable energy. The results have now been published in the International Journal of Hydrogen Energy.
Ammonia as a threat to the climate
According to the British Royal Society, global ammonia production generates around 500 million tonnes of CO₂ annually. This is equivalent to Germany’s annual CO₂ emissions and around 1.8 % of global emissions. The main reason for this is that conventional ammonia synthesis requires hydrogen, which has so far been obtained almost exclusively from natural gas – a process that releases large amounts of CO₂.
Green ammonia offers a climate-friendly alternative here – the hydrogen (H2) required is not obtained from natural gas, but from water via electrolysis. The water is split into oxygen (O2) and hydrogen using electricity from renewable energy. The resulting hydrogen then reacts with nitrogen (N2) from the air to form ammonia (NH₃) using the Haber–Bosch process.
The problem is that electricity from wind and solar energy is not continuously available. As a result, electrolysis does not constantly supply the same amount of hydrogen – the supply to the system therefore fluctuates. For an ammonia plant to respond flexibly to these fluctuations, it must be able to ramp its production up or down, i.e. it must be load-flexible.
However, conventional systems are designed for continuous, consistent operation. Rapid load changes lead to severe pressure fluctuations inside the reactors and pipelines. This places a heavy mechanical strain on the components. In order to withstand this strain in the long term, the apparatus would have to be built with thicker walls and more robust materials. This would increase costs considerably and make construction much more complex.
And this is precisely where the new study comes in. It shows how these pressure fluctuations can be reduced with an intelligent control system. This in turn reduces the requirements placed on the mechanical stability of the plants.
New solution for old fluctuations
“For green ammonia to contribute to the fight against climate change, the costs must be competitive,” says Prof. Andreas Peschel, director at Forschungszentrum Jülich’s Institute for a Sustainable Hydrogen Economy and a co-author of the study.
According to the study, this can be achieved with a new type of pressure controller in what is known as an ammonia loop. This production step ensures that unused reaction gases such as hydrogen and nitrogen are fed back into the process. According to the team’s simulations, the flexible control of this loop enables load changes to be achieved at high speed and with low pressure fluctuations.
Production output can be changed by 3 % within one minute – a speed that is not possible with today’s natural gas-based plants. This would mean that smaller buffers and thinner walls for the system components would be sufficient in future, which would reduce would reduce material costs.
In a previous study, the team presented a reactor type with flexible operation. The next step is now set to follow at Forschungszentrum Jülich – pilot plants that demonstrate the new pressure control system and high load dynamics under realistic conditions.
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