Feasibility of Saline Gradient Solar Ponds as Thermal Energy Sources in Saskatchewan, Canada

Abstract

Advancement of renewable energy is critical for sustainable development. This paper evaluates the feasibility of saline gradient solar ponds (SGSP) as an alternative energy source for Saskatchewan, Canada. The main achievements include global appraisal of SGSP from theoretical and practical perspectives, assessment of salinity and climatic criteria for SGSP potential, understanding of heat transfer mechanisms affected by thermophysical properties, and numerical modeling to simulate transient heat diffusion in SGSP. Results indicated that Saskatchewan is ideal for thermal energy harvesting from saline water bodies because of high solar insolation (1100 to 1400 kWh/m2). The solar radiation in such systems is captured under a salt concentration gradient. Locally, ten potash tailings sites (360 g/L or 36% salt) and two saline water lakes (250 g/L or 25% salt) are potentially suitable for SGSP deployment. It was found that thermal conductivity increases with temperature but decreases with water salinity increase (0.55 to 0.675 W/mK) and the opposite is true for density (1000 to 1200 kg/m3). Similarly, specific heat capacity slightly increases with temperature and inversely correlates with salinity (3000 to 4200 J/kg K). Furthermore, the heat diffusion model adequately simulated the temperature distribution for a typical SGSP in a potash tailings containment facility. For the investigated month of July (highest solar insolation), the temperatures increased from an initial value of at 20 to 52 oC at top to 37 oC at bottom. A comprehensive risk assessment of this method is required to protect air, water, soil, and biota at specific sites.

Keywords: salinegradientsolar ponds, thermal energy, natural lakes, tailings ponds, heat diffusion