In recent years, osmotic heat engine (OHE) as a novel heat-to-electricity technology has been proposed and extensively studied [
12]. The OHE is a closed-loop system consisting of a thermal separation process for thermally separating the brackish solution into high and low concentration solutions, and a power generation process for converting the Gibbs free energy of mixing the two solutions with different concentrations into electricity [
13]. It can operate under ultra-low temperature of around 40 °C, which is superior to ORC and Kalina cycle [
3]. Many efforts have been made on OHE research, highlighting the configuration optimization [
14], working condition effects [
15] and working fluid selection [
16]. Olkis et al. [
17] proposed an OHE combining adsorption desalination (AD) and reverse electrodialysis (RED), the optimization of salt and material selection is conducted. Zhao et al. [
18] presented two different heat recovery configurations of the AD-RED osmotic heat engine to improve the thermal separation performance. They also comprehensively invstigated the effect of working conditions such as adsorption time, switching time, working concentration and working fluid mass on an AD-RED osmotic heat engine [
19]. Hu et al. [
20] presented an osmotic heat engine combining multiple-effect distillation (MED) and reverse electrodialysis (RED) and investigated the effect of configuration and operation parameters on system performance. Results indicated that the increase of working concentration, operating temperature and MED effects number contributed to system performance. An energy efficiency of 1.01% can be obtained with 10 effects and working solution of 5.40 mol/kg NaCl when operated under a heat source temperature of 80 ℃. Long et al. [
21] presented an OHE consisting of membrane distillation (MD) and RED, an electricity efficiency of 1.15% is achieved with 5 mol/kg NaCl solution by optimizing the relative permeate/feed solution flow rate in MD. They also conducted a high-throughput computational screening of high-performance adsorbent for the adsorption-driven osmotic heat engines [
22]. Giacalone et al. [
23] first constructed and tested a fully operation prototype of a RED-NH
4HCO
3 thermolytic OHE and a continuous operation of over 55 h indicated the feasibility of such system. Nevertheless, the research on OHE is still in theoretical and laboratory testing stages and the practical application of electricity generated by OHE is still a knowledge gap and severely limited by intermittent power generation caused by unstable low-grade heat sources.