To store TWh of intermittent renewable energy, we need to harness it in the production of an energy carrier like ammonia (NH3). NH3 has an advantage over other synthetic fuels (e.g. methane and methanol) because it allows a CO2-free pathway for seasonal energy storage with the Haber-Bosch process, synthesizing electrolytic hydrogen (H2) and nitrogen (N2) obtained from the air at a mature and commercial level. Due to the arbitrary behavior of renewables, the current power-to-ammonia systems are equipped with large intermediate H2buffer tanks and batteries to assure a constant flow of H2and stable power supply to the Haber-Bosch process; leading to an increasing plant cost. This power-to-ammonia design can be improved by allowing a variable H2and power supply to the process while taking uncertainties into account within the dynamic Haber-Bosch system. A global sensitivity analysis quantifies then the sensitivity to these variations. The stochastic dynamic model can provide us with a flexible power-to-ammonia process while identifying the safe operations of theNH3reactor under these conditions. The current work involves the creation of a stochastic dynamic Haber-Bosch process and executing a global sensitivity analysis on the design under uncertainties. Within these uncertainties, we integrated operational (H2/N2ratio) and parametric (reactor inlet temperature) uncertainties into the model to minimize the gap between real and simulated performance. The global sensitivity analysis showed the impact of the implemented uncertainties on the ammonia plant over time. At its nominal load, the temperature variation at the inlet of the reactor is the most dominant factor, with 68.2% on the standard deviation of the ammonia production, where the H2/N2ratio influences the residual 31.8% of the output deviation. At lower loads (below 75% of the nominal load), the H2/N2variation becomes the most dominant factor, where the plant is less sensitive to the implemented uncertainties than at the nominal load. The results show that the Haber-Bosch system can be used under suboptimal conditions when fluctuating the load of the plant, but the effect of uncertainties increases toward the nominal load. The temperature variation can be decreased by installing a more precise temperature sensor. At the same time, a higher hydrogen supply towards the Haber-Bosch process would improve the efficiency of the ammonia reactor.
|Conference||International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems|
|Abbreviated title||ECOS 2020|
|Period||29/06/20 → 3/07/20|