Thermodynamic Performance of a Novel Compressed Carbon Dioxide Energy Storage System Based on Guanidinium Sulfate (Gua2SO)4) Adsorption

In recent years, energy storage technology has developed rapidly with the aim to promote the development of renewable energy sources and establish a green and sustainable energy structure. A novel compressed CO₂ energy storage system based on Gua₂SO₄ adsorption is proposed in this study. Gua₂SO₄ has low sorption enthalpy and mild physical conditions in the adsorbent and desorption process, which are very beneficial for reducing the design difficulty of low-pressure gas storage devices and improving the system performance. The energy and exergy analysis models are conducted after establishing several assumptions. The round trip efficiency, energy density, CO₂ capture unit volume and liquid CO₂ tank volume are 68.8%, 12.6 kWh/m³, 44,208 m³ and 19,235 m³ under design conditions, respectively. In addition, according to the exergy analysis, the liquefaction unit and compression unit have the highest exergy destructions. The monotonic increase in high-pressure cooler end temperature difference and ambient temperature will cause the system efficiency to show a trend of first increasing and then decreasing. The liquid CO₂ tank temperature and throttling pressure have a trade-off relationship on system performance. It should be noted that when the throttling pressure is below a certain value and the liquid CO₂ tank temperature is above a certain value, the system efficiency will sharply decrease. Moreover, increasing compressor and turbine efficiency has a conducive effect on improving system efficiency while the growth of heat exchanger pinch temperature and pressure loss rate have a negative influence to that.