Evaluating the Energy Consumption of ESP32 Microcontroller for Real-Time MQTT IoT-Based Monitoring System

Environmental monitoring is essential for a wide range of applications across different sectors and industries. However, the utilization of Internet of Things (IoT) devices for the purpose of monitoring comes with inherent challenges due to limited resources, including battery life, processing power, and storage capacity. In addition, these IoT devices are often located in remote or inaccessible areas, which makes it impractical to replace or recharge their batteries frequently. Therefore, it is crucial to optimize its energy efficiency to improve the optimal and effective functionalities of these IoT devices. The objective of this work is to examine the energy consumption of the IoT system under four different operating conditions. First, a real-time IoT monitoring system was developed using three ESP32 microcontrollers, the Message Queuing Telemetry Transport (MQTT) protocol, and the Node-RED platform. Then, the developed IoT system was used to display the temperature and humidity data of the surrounding environment through the Node-RED dashboard in real-time remotely using the MQTT protocol. Results indicate that the ESP32 with FreeRTOS consumes 27.8% more energy than the ESP32 without FreeRTOS. However, enabling deep sleep mode significantly reduces energy consumption by 83.38% when the data measurement and transmission period is set every 60 seconds, making it crucial for energy-efficient applications. The study found that ESP32 with deep sleep mode increases battery runtime up to 17.1821 days compared to ESP32 without deep sleep, which is 2.8539 days (increases up to 502.75%), making it the most effective approach for applications that need extended battery life.