Solar Desalination Driven by Organic Rankine Cycles (Orc) and Supercritical CO2 Power Cycles: An Update

In the field of desalination powered by renewable energies, the use of solar power cycles exhibits some favorable characteristics, such as the possibility of implementing thermal energy storage systems or a multi-generation scheme (e.g., electricity, water, cooling, hydrogen). This article presents a review of the latest design proposals in which two power cycles of great potential are considered: the organic Rankine cycle and the supercritical CO2 power cycle, the latter of growing interest in recent years. The designs found in the literature are grouped into three main types of systems. In the case of solar ORC-based systems, the option of reverse osmosis as a desalination technology is considered in medium-temperature solar systems with storage but also with low-temperature using solar ponds. In the first case, it is also common to incorporate single-effect absorption systems for cooling production. The use of thermal desalination processes is also found in many proposals based on solar ORC. In this case, the usual configuration implies the cycle’s cooling by the own desalination process. This option is also common in systems based on the supercritical CO2 power cycle where MED technology is usually selected. Designs proposals are reviewed and assessed to point out design recommendations.

Humidification–Dehumidification (HDH) Desalination and Other Volume Reduction Techniques for Produced Water Treatment

Volume reduction has been suggested as a novel method to tackle the various challenges associated with produced water. The present solution offers an economical and environmentally friendly solution to treat a large bulk of produced water that may overwhelm conventional water treatment methods. The current study provides a review of the various volume reduction technologies including freeze concentration, reverse osmosis, and humidification and dehumidification desalination systems. Focus is concentrated on the general HDH technologies in addition to its integration with refrigeration cycles for conditioned air production, and the power cycles for power generation. The GOR, freshwater yield, and efficiencies of the integrated HDH systems were reviewed. Lastly, innovation in the HDH desalination technology is discussed with emphasis on its incorporation with the MVC process.

Recovery of Alkaline Earth Metals from Desalination Brine for Carbon Capture and Sodium Removal

Because carbon dioxide adsorbs the radiation from the Sun and the Earth’s surface, global warming has become a severe problem in this century. Global warming causes many environmental problems such as heatwave, desertification, and erratic rainfall. Above all, erratic rainfall makes people have insufficient freshwater. To solve this problem, desalination technology has been developed in many countries. Although desalination technology can provide freshwater, it produces brine as well (producing 1 L of freshwater would result in 1 L of brine). The brine will decrease the dissolved oxygen in the sea and affect the organism’s habitat. In this study, magnesium and calcium from desalination brine were recovered in the form of magnesium hydroxide and calcium hydroxide by adjusting the pH value for carbon capture and sodium removal. Magnesium hydroxide would turn into magnesium carbonate through contacting CO2 in saturated amine carriers. Calcium hydroxide was added to the brine and reacted with CO2 (modified Solvay process). Sodium in brine would then be precipitated in the form of sodium bicarbonate. After removing sodium, brine can be released back into the ocean, or other valuable metals can be extracted from brine without the side effect of sodium. The results revealed that 288 K of 3-Amino-1-propanol could capture 15 L (26.9 g) of CO2 and that 25 g/L of Ca(OH)2 at 288 K was the optimal parameter to remove 7000 ppm sodium and adsorb 16 L (28.7 g) of CO2 in the modified Solvay process. In a nutshell, this research aims to simultaneously treat the issue of CO2 emission and desalination brine by combining the amines carrier method and the modified Solvay process.

THE INFLUENCE OF NaCl SOLUTION FLOW RATE ON ION ABSORPTION OF CAPACITIVE ELECTRIC CARBON PLATE

Research on desalination technology in seawater is being developed. This is because sea water has not been used optimally to meet community needs. One of the rapidly developing desalination systems is desalination technology using a capacitive carbon plate. The development of this desalination system technology is carried out using electrode plates made of carbon. These plates are capable of absorbing salt ions through the porous surface. The amount of ion absorbed is determined by the pore surface structure of the plate, the salt flow rate, the number of plates used, the applied voltage and other factors. The salt flow rate between the carbon plates determines the speed of the salt ions to reach the smallest pores on each plate surface. For this reason, this article has conducted research by testing the variation in the flow rate of NaCl solution to the amount of salt ions absorbed on the carbon plate.