Exergoeconomic comparison of a novel to a conventional small-scale power-to-ammonia cycle

Abstract

Ammonia is a promising carbon-free energy vector with potential applications for low carbon energy storage, transportation, power production, and fertilizer use. Small-scale renewable Power-to-Ammonia (P2A) is particularly suited for remote, agricultural areas. Employing real cost data, this work presents an exergoeconomic comparison of a novel to a conventional prototype containerized P2A system. The novel system is designed for low investment cost and is going to be tested in late 2023. Both systems have an installed 18 kWel electrolyzer capacity, yielding 1.5 kg/h of ammonia. However, the novel system has 90 000 € lower purchased equipment costs of 400 000 € and 1 800 € lower operating and maintenance costs of 20 000 €/y. The exergoeconomic analysis rightly identifies the key component in the novel design, the recycle valve, as the highest operation cost driver. However, the investment cost advantage of the valve compared to a recycle compressor in the conventional layout results in a slightly lower Levelised Cost Of Ammonia (LCOA) of 161 €/kg for the novel compared to 173 €/kg of the conventional cycle, making the novel layout overall cost superior. These values are well above values reported in literature of below 1 €/kg. However, the data presented in this work refer to a research prototype application, whose costs are strongly affected by the high engineering cost and the low number of operating hours. A mass produced prototype with a higher utilization will have much lower costs.

Keywords

• Exergoeconomic analysis
• Levelised cost of ammonia
• Small-scale power-to-ammonia