<i> CO ₂ CoDe </i> : Towards Carbon-Aware Hardware/Software Co-Design for Intermittently-Powered Embedded Systems

The upcoming battery-free Internet of Things comes with a major benefit: These systems operate energy-self-sufficiently during runtime by harvesting energy from the environment. However, the promise of thereby achieving sustainability neglects the fact that manufacturing such systems requires substantial carbon resources, eventually embodied into these systems' cradle-to-gate footprint. When developing these hard-/software systems, designers currently have no possibility to make carbon-aware decisions and assess their cross-cutting consequences throughout the system's stack (i.e., hardware, operating system, scheduler, application). To address these problems, we present CO 2 CoDe , an approach to carbon-aware co-design of embedded systems. In this paper, we exemplify the necessity of carbon-aware co-design by means of the energy-storage (e.g., capacitor) selections in intermittently-powered embedded systems. System designers have a choice of various storage types manufactured from different materials, which influence not only the environmental impact but also operational characteristics (e.g., internal resistances of capacitors). These differences in operational parameters have cross-cutting, system-wide ramifications: For example, specific types of storage have a smaller/higher carbon footprint while likewise making runtime scheduling decisions harder/easier. Our evaluations on a real-world intermittently-powered system with several capacitor types and scheduling approaches validate our optimization objective of co-designing for carbon awareness with the constraints of meeting energy budgets.