## 4 UAV Power Sources
### Laser Charging Technology  
Laser beaming is a technique used frequently in military intelligence and surveillance operations to extend missions [57]. The laser receives energy from an external source and generates a narrow, focused beam of light with a specific frequency and wavelength. This is aimed at the photovoltaic cell that was made just for a UAV. The laser beam is converted back into usable energy by this photovoltaic cell, which is used to recharge the drone's battery. On a UAV, a maximum power point tracking device can be installed to improve energy transfer efficiency. The experiment was carried out using laser beaming technology on a quadrotor UAV with a modified solar cell array that could receive energy from an infrared laser as shown in [48]. The experiment, which was carried out at the Future of Flight Museum in Everett, Washington, ultimately revealed that the given quadcopter, which had a total mass of one kilogram, was able to remain in the air for more than 12 h in a row. This technology works with both fixed-wing and multi-rotor UAVs of different sizes and does not care what the environment is like. However, the most significant drawback of this method is that a source of energy must always be mobile and close to the UAV, making it unsuitable for some long-range applications. Another issue is safety in the workplace. In general, lasers are thought to pose a risk to human health, and working with high-intensity lasers can only be done with protective gear on. Also, lasers are not allowed in all places, especially in urban areas where they can be very disruptive to people's lives [58, 59].  
Battery-powered commercial UAVs are widely used for a variety of applications, including aerial photography, surveying, inspection, and delivery. There are several types of battery-powered commercial UAVs, including fixed-wing UAVs, multi-rotor UAVs, etc. The most popular examples which are widely on the market are depicted in the first row of Table 1.  
Drones with traditional motorization, typically powered by diesel or gasoline are presented in the second row of the above table. On the other hand, the advantages of commercial solar-powered UAVs include long flight times and low operational costs since they do not require any fuel. The following examples of commercial solar-powered UAVs  
\begin{table}
\begin{tabular}{l l} \hline \hline
**Battery Powered UAVs** &
\begin{tabular}{l} **DJI Phantom 4 Pro**: The most popular quadcopter out there. Mainly used for photography and videography. \\  • **Parrot Anafi**: A fixed-wing UAV that is used for surveying and mapping. \\  • **Matternet M2**: This is a quadcopter UAV that is used for medical delivery. \\ \end{tabular} \\ \hline
**Fuel Powered UAVs** &
\begin{tabular}{l} **Yamaha RMAX**: A multi-rotor UAV that is used for agricultural purposes. \\  • **Aeryon SkyRanger**: A quadcopter UAV that is used for aerial inspection and monitoring. \\ \end{tabular} \\ \hline
**Solar-Powered UAVs** &
\begin{tabular}{l} **Sunbird Solar-Powered UAV**: A fixed-wing UAV by BAE Systems. \\  • **Airbus Solar UAV**: A fixed-wing UAV powered by solar cells and lithium-ion batteries. \\  • **Zephyr Solar-Powered UAV**: also an Airbus Product. \\ \end{tabular} \\ \hline
**Hybrid source UAVs** &
\begin{tabular}{l} **Boeing Insitu Integrator**: A fixed-wing UAV that is powered by a combination of a gasoline engine and electric motors. \\  • **Honeywell T-Hawk**: This is a vertical takeoff and landing (VTOL) UAV. \\  • **MMC HyDrone 1800**: A multi-rotor UAV that is powered by a combination of batteries and a hydrogen fuel cell. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 1: Categorized Commercial UAVs by Energy Source.  
are depicted in the third row above, which are in development or an experimental phase. Finally, the main advantage of hybrid-powered UAVs is that they have the benefits of both the power sources that are being used. Some suitable examples are shown in the last row of the table.