UK researchers have proposed the use of photovoltaic-thermal energy for desalination purposes through an approach based on synergistic electrothermal coupling mechanisms. They have found that some system configurations could provide lower desalination water level costs in addition to higher efficiency.
“However, most previous PVT desalination studies have focused on developing system integration solutions between conventional PVT collectors and desalination modules and have not considered the potential for synergistic electrothermal coupling mechanisms,” the researchers said, citing the novelty of their study. “Variations in the use of heat and electricity in desalination can improve the system’s performance, even when operating at the same solar efficiency.”
The researchers made a distinction between desalination techniques recommended for use with electricity and those based on heat. The former are reverse osmosis (RO), electrodialysis (ED), mechanical vapor compression (MVC) and capacitive deionization (CDI) solutions, while the latter are multi-stage flash (MSF) and multi-effect distillation (MED) and membrane. distillation techniques (MD).
They described all available PV and solar thermal technologies and gave a brief description of the integration mechanisms of non-synergistically integrated PVT desalination systems. They also stated that their paper is designed to explore new mechanisms that intelligently use electricity and heat from photovoltaic-thermal (PVT) systems.
Using preliminary techno-economic analysis based on performance and cost measurements, the researchers evaluated several integrated solutions for PVT desalination and their levelized cost of desalination water (RLCOW). They compared the data to figures for pure PV desalination or ST desalination systems. They also assumed that the capital and operating costs of desalination systems, auxiliaries, and hydraulic systems are the same between the PV-RO and ST-MD systems and the alternative PVT systems.
“However, the two variables considered are: (1) the water productivity of PVT desalination relative to PV desalination and ST desalination; and (2) the capital cost of PVT systems relative to PV and ST systems,” they said. “Currently, the cost of a commercially available PVT system is usually 1.5-2 times the cost of a similar PV system due to the more complex structure and the need for additional accessories for PVT systems.”
Through their analysis, the researchers found that the most common desalination technology—reverse osmosis (RO)—may have a 20% reduction in its RLCOW if energized with PVT systems compared to pure PV installations.
“Given the dominance of RO in newly installed desalination capacity and the remarkable scalability of MD as a thermally driven desalination process, the potential water cost savings show potential for an immediate positive impact that could help address off-grid water challenges.” stated.
They presented their findings “Synergies and potential of hybrid solar-thermal desalination technology, published Desalination. The research team includes researchers from Imperial College London and King’s College London.
“Further research should be done to elucidate the electrothermal coupling mechanism and develop parametric theories/models for the combined use of electricity and heat in various desalination processes,” they concluded.
