Green Unmanned Aerial Vehicles: A Review of Hydrogen Fuel Cell and Solar-Powered Drones

ABSTRACT: Unmanned aerial vehicles (UAVs) are increasingly used in applications such as agriculture, logistics, mapping, surveillance, and environmental monitoring. However, the limited battery endurance continues to restrict mission duration and operational range. This review examines two sustainable propulsion alternatives, hydrogen fuel cells and solar-powered systems, based on findings reported in the literature. Evidence from peer-reviewed studies, experimental demonstrations, and industrial reports published between 2009 and 2024 is considered. Key parameters, including endurance, payload capacity, and operational altitude, are compared, along with practical aspects such as hydrogen storage, thermal management, and energy control systems. The available data suggest that hydrogen fuel cell (HFC) drones are better suited for low to mid-altitude missions requiring higher payload and rapid refueling. Solar-powered drones are more effective for long-endurance and high-altitude applications under favorable solar conditions. Future developments are expected to focus on hybrid propulsion systems, improved materials, and more efficient energy management strategies.