Water-energy nexus approach to compare performance of evaporative and vapor-compression cooling systems

Evaporative cooling systems consume high water, but low electricity for their operation. On the other hand, vapor compression systems consume no water, but high electricity. Water and energy systems are interconnected at different levels. Therefore, water use causes an off-site electricity use, and also electricity use results to off-site water use. Therefore, there is a strong trade-off between electricity and water use in these cooling systems. Depending on the water and electricity mix of the region, this tradeoff is very region-specific. This research aims to use a nexus thinking to quantify this trade-off and identify the proper cooling strategy for energy-poor and water-poor regions. A dynamic hourly simulation was performed to evaluate the hourly on-site and off-site water and energy use by two systems for the summer season in Tehran. It resulted that heat pump system consumes both higher water and electricity than the evaporative system, which is resulted by high water intensity of the electricity mix in Iran. Results show the importance of nexus thinking to prevent shifting problems from one sector to another.