How does a resilient, flexible ammonia process look? Robust design optimization of a Haber-Bosch process with optimal dynamic control powered by wind

Ammonia can be an essential energy vector for storing excess renewable energy during the year and release this energy when demand is high. This storage during the year provides an essential part in the energy sector for moments when there is not enough wind and sun to cover the demand. Although the Haber-Bosch is a very mature process to synthesize hydrogen and nitrogen to ammonia, it is not flexible enough to match the erratic nature of renewables. This mismatch creates the need for large intermediate hydrogen buffer tanks. To reduce the capacity of the hydrogen storage tank, we need to optimize the dynamic power-to-ammonia process in a minute time scale while considering the uncertainties linked to renewables. Therefore, we coupled a stochastic wind power process to a dynamic Power-to-Ammonia process and performed a design optimization under uncertainties, i.e. a robust design optimization, for a three-hour wind scenario while considering optimal dynamic control. The robust design optimization showed significant trade-offs between the most productive, the most flexible, the most resilient, and robust power-to-ammonia plant designs. For the flexible and productive designs, the bypass fraction and buffer feed have essential roles in achieving these designs. In the future, we will use a stochastic process to consider the uncertainty of renewable power over more extended periods (days, weeks and months) coupled with the robust design optimization of the dynamic power-to-ammonia process and investigate its effect on the intermediate hydrogen buffer size and the plant’s cost.