Projecting global water footprints diminution of a dew-point cooling system: Sustainability approach assisted with energetic and economic assessment.

In the coming decades, a large portion of the world population is expected to embrace urbanization. The demand for thermal comfort in populous and congested urban centres, especially in developing countries across the globe, is expected to rise many folds. Alternates to conventional air-cooling systems are water-based evaporation cooling. Recently introduced efficient multi-stage indirect evaporative cooling using the Maisotsenko(M)-Cycle has shown success with improved performance by theoretically reaching the dew-point of the incoming air. However, the impact of large-scale use of such cooling devices shall inadvertently leave huge strains on the urban useable water resources. On the other hand, cooling, as usual, is not sustainable with the global demand for air cooling units shall grow many folds up to 5.0 billion units over the next decade compared to currently 1.3 billion in service units. Alternates of high electricity consuming air cooling, such as Maisotsenko cycle based devices are part of the solution only if the water impact can be brought to minimal in an efficient manner. A key development in this regard is the utilization of water recovery systems from waste air streams leaving air coolers. A few studies and models have shown their successful working and predictions. This paper initially analyzes the global impacts of air-cooling devices using the commercially available product designed to work on the Maisotsenko cycle. Moreover, the impact of these devices on the global scale in terms of utility as well as their water footprints are estimated. The results produce a grim picture since most favourable zones/regions in the globe for indirect evaporative cooling are also labelled as high on the water stress index. Secondly, global assessment of water recovery unit in terms of reduction in water footprint and combined cooling and recovery system Energy Efficiency Ratio (EER) are also assessed. Based on the assessments and predictions of global economic parameters, a wholesome Levelized Cost of Electricity of combined air cooling and water recovery system is estimated for each zone across the globe favourable for the Maisotsenko cycle based air cooler. The hypothesis postulate that the global projections of the energy-efficiency-ratio should be improved while diminishing its water footprints at a lower Levelized cost. The prime purpose of the research is to evaluate the technological advancement presented in the commercial M50 air cooler for energetic, economical, and water-related indicators with the consideration of global projections in similitude to the social contexts of the region. Our hypothesis is verified with our assessment and the principal results have suggested that recovering the water from M-50 cooler, a commercially available device working on M-Cycle, yields in the reduction of specific water usage per ton of air cooling by ~63% while the EER improved by ~26% as compared to the conventional air cooling and the Levelized Cost of energy is 0.014 USD/kWh which is much lower than the conventional air conditioning systems. The findings of this article have concluded that proposed technological advancement has better performance indicators, suiting the complicated local context, and it is suggested/recommended to the governments (especially the Middle East, South Asian, Central Asian, North African, and Australia) to include such natural air coolers (particularly M-Cycle machines) in the national energy efficiency plans to meet the global sustainability targets of United Nations. Image 1 • Maisotsenko air cooler can be a possible sustainable and futuristic air-cooling device. • Global and mass scaling of these machines can generate water-energy nexus. • An energetically-efficient method to decrease the water footprints is demonstrated. • Global projection of thermoeconomics and water footprints are plotted. • The findings can help policy-making bodies to decide the sustainable future of air-conditioning. [ABSTRACT FROM AUTHOR]