The field of energy harvesting and efficient communication systems is witnessing significant advancements, driven by the need for sustainable and environmentally friendly solutions. Researchers are exploring innovative approaches to harness energy from various sources, including solar, kinetic, and RF energy, to power devices and systems. Meanwhile, the development of efficient communication systems, such as those employing reconfigurable intelligent surfaces (RIS) and UAV-enabled wireless-powered networks, is gaining traction. These systems aim to minimize energy consumption while maintaining high performance and security. Notably, the integration of energy harvesting and efficient communication systems is expected to play a crucial role in enabling emerging applications, such as IoT, wireless sensor networks, and low-altitude economy. Some noteworthy papers in this area include: On the Trade-Off Between Sum-Rate and Energy Efficiency, which investigates the integration of active RIS relay with high-altitude platform stations to enhance non-terrestrial network performance. Feasibility of Energy Neutral Wildlife Tracking, which presents an energy-neutral system combining solar and kinetic energy harvesting for wildlife tracking. LLM Meets the Sky, which proposes a hierarchical optimization framework for secure heterogeneous UAV networks under propulsion energy constraints.