Defragmenting Energy Storage in Batteryless Sensing Devices

Batteryless devices operate by storing the harvested energy in capacitors. In single capacitor-based systems, the whole energy stored in the system is available to all peripherals, and power-hungry hardware components might drain the energy in the capacitor quickly. Federated energy storage architecture enables the use of separate storage units dedicated to each peripheral and decouples the energy consumption of peripherals from each other. However, in this architecture, the overall harvested energy is distributed into separate smaller capacitors. This leads to energy fragmentation that prevents the overall distributed energy from being used by applications. In this paper, we aim at the design of an energy storage architecture that combines the benefits of centralized and federated energy storage architectures. To this end, we introduce GRANT (enerGy defRAgmeNTer) that defragments the available energy in a federated energy storage architecture. Via LTSPICE simulations, we present some initial results describing how efficient GRANT defragments the available energy.