  To mitigate the growing carbon footprint of large-scale computing systems,
there has been an increasing focus on \emph{carbon-aware} approaches that seek
to align the power usage of IT infrastructure with the availability of clean
energy. Unfortunately, research on carbon-aware applications and the required
interfaces between computing and energy systems remain complex, due to the
scarcity of available testing environments. To this day, almost all new
approaches are evaluated on custom simulation testbeds, which leads to repeated
development efforts and low comparability of approaches.
  In this paper, we present our vision of a co-simulation testbed for
carbon-aware applications and systems. We propose a versatile testbed which
lets users connect domain-specific simulators for components like renewable
power generation, energy storage, and power flow analysis with real software
and hardware. By providing extensibility on the one hand and access to
state-of-the-art implementations and datasets on the other, we hope to
accelerate research in carbon-aware computing. In addition, a co-simulation
testbed can be useful for development and operation, like in continuous
testing. We implemented a working prototype of our idea and welcome the
community to contribute to this vision.

Distributed, Parallel, and Cluster Computing;Systems and Control;Systems and Control