Design and Power Management of Energy Harvesting Embedded Systems

Harvesting energy from the environment is a desirable and increasingly important capability in several emerging applications of embedded systems such as sensor networks, biomedical implants, etc. While energy harvesting has the potential to enable near-perpetual system operation, designing an efficient energy harvesting system that actually realizes this potential requires an in-depth understanding of several complex tradeoffs. These tradeoffs arise due to the interaction of numerous factors such as the characteristics of the harvesting transducers, chemistry and capacity of the batteries used (if any), power supply requirements and power management features of the embedded system, application behavior, etc. This paper surveys the various issues and tradeoffs involved in designing and operating energy harvesting embedded systems. System design techniques are described that target high conversion and storage efficiency by extracting the most energy from the environment and making it maximally available for consumption. Harvesting aware power management techniques are also described, which reconcile the very different spatio-temporal characteristics of energy availability and energy usage within a system and across a network.