Hybrid solar photovoltaic and salinity-gradient based osmotic energy conversion system with synergistic performance enhancement

Abstract

Solar photovoltaic has become essential for generating renewable electricity to overcome global crisis of fossil energy. However, solar photovoltaic suffers from a dramatic decrement on its output power when panel surface temperature is extremely high. In addition, osmotic energy conversion is a fascinating route for utilizing energy existed between ionic aqueous solutions with salinity-gradient. Nevertheless, osmotic energy conversion also confronts a drawback of insufficient power density. When the ionic aqueous solution temperature increases, the osmotic power generation under salinity-gradient is improved owing to the strengthened ion selective diffusion. Under these circumstances, we present a hybrid solar photovoltaic and osmotic energy conversion system, and their power generation performance can be synergistically improved via heat transfer from solar photovoltaic panel to ionic aqueous solution using high thermal conductive copper heat pipes. The theoretical modelling indicates that output power of solar photovoltaic is increased by 22.8 % with a decreased panel surface temperature of 35.6 °C by using 10 copper heat pipes, while the corresponding osmotic power with a salt concentration ratio of 50-fold is simultaneously increased by 36.8 %. Then, a hybrid solar photovoltaic and osmotic energy conversion system is experimentally constructed. Due to heat transfer from photovoltaic panel to ionic aqueous solution through 10 copper heat pipes, the maximum surface temperature of photovoltaic panel is dropped from 67.3 °C to 43.4 °C, and its output power is consolidated by 35.2 %. Besides, the osmotic power density under 50-time salinity-gradient ratio is synergistically ameliorated from 1.39 W/m2 to 2.72 W/m2 by 95.7 %. The current research designs a hybrid solar photovoltaic and osmotic energy conversion system, paving a fetching way for synergistic utilization of solar energy and salinity-gradient energy.