ABSTRACT
Contents 12.1 Introduction ............................................................................................. 318 12.2 Energy Harvesting ................................................................................... 318
12.2.1 Motivations for Energy Harvesting ............................................... 319 12.2.2 Energy Harvesting: A Possible Solution ........................................320
12.3 Energy Harvesting: Beyond the Solar Harvester-Is It a Viable Option? ..................................................................................... 321
12.4 Storing Harvested Energy ........................................................................324 12.4.1 Energy Harvesting System ............................................................325 12.4.2 Experimental Measurement ..........................................................328
12.5 Energy Budgets: System and Network Operations ...................................329 12.5.1 Energy Harvested Applications: Challenges ..................................331 12.5.2 Storage and Retrieval of System State ...........................................335 12.5.3 Toward a Distributed Smart Application: Challenges ...................336
12.6 Summary .................................................................................................338 References .........................................................................................................338
12.1 Introduction Miniaturization and improvements in the communication and computation capabilities of devices is bringing about steep growth in wireless communication devices. ‡e exploding number of devices comes with the immediate task of supplying them with energy. ‡us, energy harvesting has become an important aspect. Energy that is harvested from sources such as solar panels, vibration, and thermogenerators, provides varying instantaneous power. We focus on the performance of energyharvesting embedded sensors and study the problems associated with applications that assume constant power harvesting. We begin the chapter by taking a simple environment-sensing application and show its baseline performance under the trivial assumption of constant power availability. We then propose simple mechanisms specific to harvested power-enabled wireless sensor nodes to constantly adjust their operational schedule based on the incoming energy profile. In the initial part, we begin with system-related node operations and further extend this to a network of wireless sensor nodes. Since energy availability can be different across the nodes in the network, even if similar harvesting is used, network setup and collaboration is a nontrivial task. At the same time, in the event of excess harvested energy, the collaboration between nodes is possible, which is exciting, but also challenging. Operations such as sensing, computation, storage, and communication are required to achieve the common goal for any sensor network.
