Sustainable Green Unmanned Aerial Vehicles (UAV) Systems for Smart and Environmental Applications: A Review

Unmanned Aerial Vehicles (UAVs), as a unique enabler, have been widely used for smart city and environmental applications owing to their agility, flexibility, and large-scale sensing capability. Nevertheless, the widespread and long-term use of such systems is restricted by the energy stored on board, impact on the environment as well as sustainability issues. Existing survey work is primarily aimed toward energy or communication efficiency, and a holistic sustainable prospective is not yet to be found. Research contribution The research contribution is a review of usable (sustainable green) UAV systems for smart and the environmental applications with categorisation (taxonomy) which systematically categorises existing work. Recent literature is structured along sustainability scope, green enabling technology, level of intelligence, application domains, evaluation methods and performance metrics. A systematic literature review of peer-reviewed articles published between 2019 and 2025 was carried out. The results reveal that about 75% focus on operational energy efficiency, less than a quarter cover security, privacy or trust aspects, and less than 20% full lifecycle sustainability. Recent developments are witnessing the convergence of AI,energy harvesting (EH) and edge computing to enhance the endurance and autonomy of UAVs. However, the structured evaluation frameworks, long-term real-world validation, and integrated sustainability-aware designs are still some of the challenges. The current review in playing a balancing role is expected to bridge this gap by highlighting some of the significant research gaps and strategic directions that can steer the development of cost-effective, intelligent and environmentally benign UAV systems.