Temporal and spatial variability of energy intensity for atmospheric water generators

Abstract

Atmospheric Water Generators (AWG) produce potable water from the moisture in the air, providing a potentially viable water source in austere locations or emergency response scenarios. In this study, the operating constraints of three existing commercially available AWG devices are investigated, compared to historical weather data from across the continental United States. Utilizing linear regression modeling and weather station data for the years of 1985-2019, the monthly and spatial trends of energy demand to produce water from these devices are estimated. Energy and water production efficiencies for the devices are highly dependent on environmental conditions with relative humidity and temperature as the two driving factors. Publicly available manufacturer specifications for each AWG system were modeled to predict yield and specific energy consumption. A spatial analysis depicts the change in specific energy consumption in kilowatt-hours per liter (kWh/L) across the country at a monthly scale. Specific energy consumption for refrigeration AWG ranged between 0.02-3.64 kWh/L and solar driven sorption was between 3.19-5.29 kWh/L, significantly larger than conventional water treatment energy demands. Additionally, the results are synthesized based on the Köppen-Geiger climate classification system, to approximate projected water production and energy demand for each environment, with arid climates demanding larger energy consumption per unit volume of water produced. Excluding arid and cold climate classes, solar powered refrigeration devices have the potential to operate more efficiently than solar driven sorption due to advances in photovoltaic solar panel technology, but still require more energy than alternatives.