Theoretical component design and thermo-economic performance of liquid ammonia water mixture energy storage system

To reduce carbon emissions and slow down temperature rise worldwide, renewable energy is proposed as a substitute for traditional fossil fuel. Additionally, energy storage systems play an important role in addressing the intermittency issue of renewable energy. Among various energy storage systems, the liquid ammonia water mixture energy storage system, which uses the ammonia water mixture as the storage fluid, is proposed and investigated in this work. The thermo-economic performance of the liquid ammonia-water mixture energy storage system is investigated and the design of key components is conducted. The parametric sensitivity analysis is conducted to examine the influence of independent variables on the system thermo-economic performance. The results show that the roundtrip efficiency, energy storage density and levelized cost of storage under baseline condition are 44.39 %, 49.79 kWh/m3 , and 0.3100 $/kWh, respectively. The turbine and compressor are the most and second most expensive components, accounting for more than 50 % of total component purchase cost. Besides, among the 12 months of 2024, the levelized cost of storage under September has the best performance with 0.2891 $/kWh. Moreover, the optimal net present value is negative, indicating that the proposed system is currently not profitable for investment. However, the system thermo-economic performance can be further improved by enhancing the system itself, such as increasing the isentropic efficiency of compressor and turbine. In addition, a lower interest rate has a huge positive effect on the levelized cost of storage.