in Wiley Online Library (wileyonlinelibrary.com)Chemicals-based energy storage is promising for integrating intermittent renewables on the utility scale. High roundtrip efficiency, low cost, and considerable flexibility are desirable. To this end, an ammonia-based energy storage system is proposed. It utilizes a pressurized reversible solid-oxide fuel cell for power conversion, coupled with external ammonia synthesis and decomposition processes and a steam power cycle. A coupled refrigeration cycle is utilized to recycle nitrogen completely. Pure oxygen, produced as a side-product in electrochemical water splitting, is used to drive the fuel cell. A first-principle process model extended by detailed cost calculation is used for process optimization. In this work, the performance of a 100 MW system under time-invariant operation is studied. The system can achieve a roundtrip efficiency as high as 72%. The lowest levelized cost of delivered energy is obtained at 0.24 $/kWh, which is comparable to that of pumped hydro and compressed air energy storage systems.All cost data except that for the ammonia-based energy storage system are reproduced from Rastler. 8 [Color figure can be viewed at wileyonlinelibrary.com] 1 Stage number of the turbines [E-30/37,RE-5/7] Re HX 5000 Reynolds number of the main streams of all heat exchangers DV, decision variable; CP, calculated parameter; SP, specified parameter; SV, specified value.

Decarbonization of the power sector offers ammonia industry an opportunity to reduce its CO 2 emissions through sector coupling. Extending from our previous work, we propose a power-based process for ammonia and nitric acid production. The coupling of nitric acid production facilitates highly efficient heat integration between steam electrolysis and the rest of the process. We investigate the economic performance of the production complex through a model-based dynamic optimization approach, considering scenarios with or without incorporation of intermittent wind power as well as deployment of battery storage. In all cases, the wind power integration proves to be economic with a peak-to-base load ratio of up to 2.3. The new process reduces primary energy consumption by more than 13% compared to conventional technologies. However, it is only economically competitive with help of either a low-cost battery storage or a higher carbon price on fossil fuels. The results also confirm the importance of considering process dynamics during process design. K E Y W O R D S dynamic optimization, electrification, Haber-Bosch, process design, sustainability

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