This chapter explores the recent approaches toward achieving zero-energy consumption in wireless communication systems, focusing on the integration of zero energy devices (ZED) in the wireless communication systems. First, we delve into the design of wireless communications with ZEDs powered by natural energy sources and highlight the challenges associated with it. We elaborate on the design of efficient power control policies which not only optimize the energy consumption but also facilitate the uncoordinated operation of these wireless links. Next, we introduce the captivating domain of radio frequency (RF) energy harvesting (EH) which holds significant promise as a key enabler for zero-energy devices, harnessing ambient electromagnetic signals to power communication devices and sensor networks. We provide insights into the principles, challenges, and potential applications of RF energy harvesting, by offering a comprehensive overview of wireless power transfer (WPT) and its generalization, termed as simultaneous wireless information and power transfer (SWIPT). By drawing the insights into the interplay of wireless communications and natural energy harvesting, and unraveling the possibilities of RF energy harvesting (controlled source), the conceptual frameworks presented herein provide a foundation for the design and implementation of energy-efficient, sustainable, and eco-friendly wireless communication systems.