The paper considers the characteristics of the energy budget for mobile base stations (BSs) in the form of Unmanned Aerial Vehicles (UAVs) equipped with Radio Frequency (RF) transceivers, Intelligent Reconfigurable Surfaces (IRSs), and Renewable Energy Sources (RESs). The obtained results highlight the benefits and challenges related to using the aforementioned mobile base stations from the energy side. The research cases took into account two types of UAV devices - multirotor and fixed-wing (airplane-like).