This paper addresses the implementation of an energy recovery system in a category O2 trailer. Energy recovery systems for transport, including regenerative braking in hybrid (HEV) and battery-electric (BEV) vehicles, are reviewed. Two main regenerative braking strategies are presented and discussed: serial and parallel. Solutions for braking systems in O1 and O2 trailers are discussed, focusing on the two most popular solutions: electric and overrun. The overrun system was chosen as the basis for further work due to its simple design and popularity in trailer applications. The next section of the paper presents the concept of an electric energy recovery system in a trailer. A modification of the driving axle of a fully refrigerated trailer is proposed. The system utilizes an electric motor operating solely in generator mode. Concepts for controlling the electromagnetic clutch are developed based on signals from the IVECO DAILY vehicle's CAN bus. Traction calculations were performed for an IVECO eDaily electric vehicle in four variants: without a trailer, with an empty trailer, with half the permissible trailer load, and with a full trailer load. The results indicated a significant effect of the trailer weight on the traction characteristics of the vehicle and trailer combination. A key element of the work was the development of a simulation model in MatLab Simulink, which performs calculations based on the relevant relationships specified in the work. Simulation studies were conducted for four driving profiles: a standardized WLTC cycle and three actual cycles recorded by the author. Each cycle was tested with three trailer load variants. The highest value of recovered energy was 5.4 kWh, which would allow a 1.6 kW refrigeration unit to operate for 3.5 hours, bringing economic and environmental benefits. Based on the simulation studies and the entire workflow, the obtained results were summarized, conclusions were drawn, and further research was proposed.