Novel Thermal Desalination with Solar PV driven CO2 Heat Pump and additional Cooling Benefits

This study proposes and analyses the performance of an innovative thermal desalination arrangement characterized by its space-efficient, vertical configuration, akin to vertical farming. Central to this system is a CO₂ heat pump, employed as an environmentally friendly technology to heat seawater. Notably, the system also explores methods to utilize the cooling effects generated by the heat pump. The energy required for the heat pump is supplied by a solar photovoltaic (PV) array, designed following agrivoltaic principles to enable dual land use for both energy production and agricultural activities. This approach allows the land to serve both energy production and agricultural purposes, optimizing resource utilization. Drawing inspiration from traditional solar stills, this desalination system differentiates itself by indirectly utilizing solar energy to power the CO₂ heat pump, rather than directly heating the water. Accordingly, a metal plate replaces the typical glass cover, and a water spraying or cooling mechanism is proposed to maintain the surface temperature near ambient levels, thereby enhancing the yield of desalinated water. Use of metal plate permits stacking of such system, furthrt reducing land use. The water flow rate is regulated by the evaporation rate to ensure a steady state. A laboratory-scale experimental validation is provided, suggesting higher productivity of de-salinized water compared to conventional solar stills. A comparative economic analysis of the proposed system is also presented. Ultimately, it addresses critical challenges of freshwater scarcity, land utilization, and cooling requirements, offering a viable solution for seawater desalination.