Suitability of Atmospheric Water Harvesting (AWH) techniques for the climatic conditions of Pakistan: A case study
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Abstract
This study explores the viability of Atmospheric Water Harvesting (AWH) techniques as a cost-effective solution for alleviating drinking water scarcity in Pakistan, considering its diverse climatic conditions. The future prospects of AWH techniques are evaluated in terms of their ability to offer independence from traditional water sources, climate resilience, self-sufficiency, emergency response capabilities, agricultural applications, and promotion of renewable and sustainable development. Specifically, the study focuses on the Vapor Compression Refrigeration (VCR) cycle and the Warka Water Tower (WWT) as potential AWH solutions. The VCR technique demonstrates a water production capacity of 18.3 L/day, achieved by utilizing relative humidity ranging from 60% to 80% and ambient temperatures between 15°C to 35°C. WWT harnesses atmospheric resources such as relative humidity, fog, and dew water, making it a viable option for water production in remote areas, including mountainous and desert regions. Under minimal favorable climatic conditions characterized by relative humidity between 60% to 75% and temperatures ranging from 20°C to 40°C. WWT can generate up to 100 L/day (26.4 gallons) of safe drinking water. The portability and cost-effectiveness of the WWT, facilitated by its use of biodegradable construction materials, make it an attractive solution that can be easily relocated as required. This study underscores the VCR technique as the optimal AWH solution for Pakistan's arid, semi-arid, and coastal regions due to its efficient operation, reasonable initial investment cost, and favorable Return on Investment Period (RIP) 7 to 8 months, with water production cost 40-45 Rs/L. Additionally, the WWT exhibits significant potential of providing safe drinking water in remote areas. These findings contribute to the development of effective AWH technologies tailored to the unique climatic conditions of Pakistan.
Keywords: Atmospheric water generator; Climatic conditions; Relative humidity; Vapor compression refrigeration; Warka water tower