Comparative thermoeconomic assessment of renewable-driven hybrid-cooled sustainable greenhouses for subtropical regions

Abstract

The rapid population growth in subtropical regions and heavy reliance on food imports have led to many countries facing food insecurity. In subtropical regions, the combination of high ambient temperatures, intense solar radiation, lack of fertile soil, and limited freshwater resources create an inadequate environment for agriculture production. Without sustainable and innovative solutions, cultivation in subtropical regions will become energy-intensive, expensive, and susceptible, if not entirely unattainable. Therefore, this research work delves into assessing the thermoeconomic performance of 10 renewable-driven hybrid-cooled greenhouse integrated systems based on different solar power generation technologies, cooling cycles, and desalination systems. Four greenhouse configurations are simulated: Closed greenhouse, shaded greenhouse, buried greenhouse, and buried and shaded greenhouse. Firstly, passive cooling techniques' potential to reduce active-cooled greenhouse cooling demand and water usage was investigated, taking into account the need to provide crops with adequate environmental temperature, solar irradiation, and ventilation. Secondly, a detailed thermodynamic analysis was conducted to obtain the overall energy and exergy efficiencies of the investigated greenhouse integrated systems. Thirdly, a comparison of solar panels area requirement for the greenhouse integrated systems was performed. Finally, a comprehensive life cycle cost analysis of the examined integrated systems for the hybrid-cooled greenhouses was done to compare their economic performance. The results showed that the adopted passive cooling methods reduced yearly cooling load by 34.2–58.1%, evapotranspiration during maximum cooling load day by 17.4–34.1%, solar panels area by 8.5–32.1%, and integrated systems' life cycle cost by 5.6–28.6%. Greenhouse integrated systems powered by photovoltaic panels obtained the lowest life cycle cost, while greenhouse integrated system-4 driven by concentrating photovoltaic thermal panels was found superior in terms of panels area.