ABSTRACT
Wireless sensor networks are becoming widely used in applications that need continuous monitoring. One of the main causes of their popularity is their low cost of access, installation, and maintenance, in addition to flexibility and scalability. Therefore, various energy sources are currently being evaluated for continuous and long-term operation. The potential to deploy WSNs in remote and difficult-to-access locations promotes the evaluation of batteries recharged by renewable energy sources. The most common source is usually photovoltaic energy; however, its restriction to the daytime requires batteries with high storage capacity. In addition, other sources for energy harvesting are mentioned, as well as hybrid systems that combine more than one energy source. On the other hand, the analysis of power consumption is mentioned: it is important to understand that wireless sensor networks consist of sensors/actuators whose power supply is wireless communication systems or ready-made systems, such as motes which detect the components ready for communication and turn on their power supply—otherwise, they are in sleep mode. Additionally, the power requirement of a node within a sensor network are defined by the lifetime of its battery. Some ideas to decrease energy consumption are specified in this chapter, such as hardware and firmware control. Lastly, the architecture for nodes to perform properly is specified, such as processing elements and real-time clock, among others. In particular, a sensor node has a relevant feature which consists of remaining in operation without battery recharge for years, improving its efficiency in the long term.
