A photovoltaic-powered rapid-cycling sorption system for sustainable off-grid atmospheric water harvesting

Abstract

Sorption-based atmospheric water harvesting (SAWH) technology exhibits great potential for strong environmental adaptability and flexible deployment. However, current systems commonly rely on grid electricity or intermittent solar thermal sources, which makes continuous and stable operation difficult and limits application reliability and scalability. Herein, an innovative photovoltaic (PV) powered rapid-cycling SAWH system was proposed for sustainable off-grid water harvesting. Activated carbon fiber felt (ACFF) acted as both an adsorbent and a resistor. In-situ electric swing adsorption (ESA) technology was employed to enable the adsorbed ACFF to undergo rapid Joule heating and desorption. The SAWH system achieved four daily cycles with a single sorption bed by optimizing the adsorption–desorption strategy. Experimental results showed that under 15 °C and 70 % relative humidity, the fan-assisted water cooling condensation mode was utilized to achieve a daily water production (DWP) of 0.96 kgwater/kgACFF/day with a low specific energy consumption (SEC) of 2.59 kW·h/kgwater. Even in the arid climate of Kunming during January, an equal-time adsorption mode (4.5 h × 4) was adopted to maintain a DWP of 0.50 kgwater/kgACFF/day with a SEC of 4.86 kW·h/kgwater. A six-day outdoor water collection test demonstrated that the PV panels consistently supplied sufficient energy to meet the SAWH system's demand, with an energy conversion efficiency above 15 %. This stable power supply enabled continuous freshwater production under varying weather conditions, including sunny, cloudy, overcast, and nighttime days. The results validated the feasibility and practicality of this study as a green and sustainable solution for clean water harvesting.