The efficiency η of a thermogravitational cycle depends on the thermodynamic processes the working fluid goes through during each step of the cycle. Below some examples:
* If the heat exchanges at the bottom and top of the column with a hot source and cold source respectively, occur at constant pressure and temperature, the efficiency would be equal to the efficiency of a Carnot cycle:
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* If the working fluid stays at the liquid stage during the compression stage 1→2, the efficiency would be equal to the Rankine cycle efficiency. By noting h, h, h and h the specific enthalpies of the working fluid at stages 1,2,3 and 4 respectively:
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* If the working fluid remains a gas during all the steps of a thermogravitational cycle, the efficiency would be equal to the Brayton cycle efficiency. By noting γ the heat capacity ratio:
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