Energetic analysis and economic viability of active atmospheric water generation technologies

Abstract

Water scarcity is a growing global and systematic problem in regions with low groundwater availability. Atmospheric water generation (AWG) technologies are an innovative solution to the water shortage problem, as atmospheric water vapor is a readily available resource even in arid regions, with the drawback of high energy consumption. In this paper, the viability of AWG technologies on an energy and economic level is investigated by thermodynamic modeling of three main active AWG systems consisting of cooling condensation, adsorption and absorption processes. A location analysis model is developed to evaluate the performance based on representative weather data of temperature, pressure and relative humidity over a period of one year to account for seasonal shifts and daily variations in climatic conditions. The specific energy consumption kWh/kg, water production trend and total specific cost are calculated for each technology. Water production by seawater desalination at the nearest coastline and transportation to the site by tanker truck, as well as bottled water prices, are used as benchmarks to assess economic viability. The results show that active AWG systems can only be an economically viable alternative if the water consumption site is relatively far from the coast or other water-rich regions and low electricity costs are available (distance >600 km, electricity price <0.10 US$/kWh). Compared to bottled water, all AWG technologies are in a competitive price range. Absorption systems have an energy efficiency advantage over conventional cooling condensation and adsorption systems (cooling condensation: average 0.42 kWh/kg; absorption: average 0.38 kWh/kg; adsorption: average 1.16 kWh/kg), but require a higher degree of process and plant design development. However, because of the high fluctuation in water production, atmospheric water generation technologies should be considered as a complementary supply to conventional water sources.