Abstract: Windows of a vacuum chamber of an AWG are opened to allow air in. Water is absorbed from the air in a hygroscopic material coating the outside of a heat transfer chamber. When the hygroscopic material reaches a certain level, the windows are closed, a vacuum is created in the vacuum chamber, water vapor is released from the hygroscopic material, and the water vapor is pumped from the vacuum chamber into the heat transfer chamber. The pumped water vapor is condensed into water in the heat transfer chamber and energy is transferred from condensation back to the hygroscopic material through one or more walls of the heat transfer chamber. When the water in the heat transfer chamber reaches a certain level, the water is transferred from the heat transfer chamber to the reservoir, the pump is stopped, the vacuum is released, and the windows are opened again.