Low-temperature desalination driven by waste heat of nuclear power plants: A thermo-economic analysis

Nuclear desalination is one of the ideal options to achieve net zero emissions. However, most nuclear desalination plants extract steam from the power cycle to drive desalination, leading to a reduction of electricity output. To avoid the parasitic effects of desalination on the power cycle, this study considers recovering waste heat from the power plants' condensers to drive low-temperature desalination systems, including spray-assisted low-temperature desalination system (SLTD), multi-effect distillation system (MED) and spray-assisted multi-effect distillation system (SMED). Thermodynamic and economic models of the three desalination systems are firstly established and validated with experimental data. Then, the impacts of key design, operation and economic parameters are evaluated using the validated models. Results reveal that the productivity and thermodynamic efficiency are promoted by increasing the cooling water flowrate of desalination condenser, enlarging the heat exchanger area and lifting the heat source temperature, while the number of effects has an optimal value of 3. Under the optimal configuration, the gained-output ratio and Second Law efficiency of a 20 m3/day SLTD plant are 0.71 and 1.25 % respectively. In terms of economic performance, the levelized-cost of desalinated water (LCOW) for three plants can be reduced substantially under a larger plant capacity and longer lifespan. When the plant capacity exceeds 20,000 m3/day, the LCOW of SLTD can be reduced to 0.757 $/m3, which is lower than all other desalination systems coupled with power plants or renewable energy sources.