Environmentally-powered computer systems operate on renewable energy harvested from their environment, such as solar or wind, and stored in batteries. While harvesting environmental energy has long been necessary for small-scale embedded systems without access to external power sources, it is also increasingly important in designing sustainable larger-scale systems for edge applications. For sustained operations, such systems must consider not only the electrical energy but also the thermal energy available in the environment in their design and operation. Unfortunately, prior work generally ignores the impact of thermal effects, and instead implicitly assumes ideal temperatures. To address the problem, we develop a thermodynamic model that captures the interplay of electrical and thermal energy in environmentally-powered computer systems. The model captures the effect of environmental conditions, the system's physical properties, and workload scheduling on performance. In evaluating our model, we distill the thermal effects that impact these systems using a small-scale prototype and a programmable incubator. We then leverage our model to show how considering these thermal effects in designing and operating environmentally-powered computer systems of varying scales can improve their energy-efficiency, performance, and availability.

翻译：环境供电计算机系统通过从环境中采集的可再生能源（如太阳能或风能）运行，并将能量存储在电池中。虽然早在无外部电源的小型嵌入式系统中就需采集环境能源，但在设计可持续的边缘应用大型系统时，这一点也日益重要。为维持持续运行，此类系统在设计与操作中不仅需考虑电能，还需考虑环境中的热能。遗憾的是，现有研究通常忽略热效应的影响，而隐式假定理想温度条件。针对这一问题，我们构建了一个热力学模型，捕捉环境供电计算机系统中电能与热能的相互作用。该模型可刻画环境条件、系统物理特性及工作负载调度对性能的影响。通过小规模原型系统与可编程恒温箱的评估，我们提炼出影响此类系统的关键热效应。进而利用该模型证明，在设计及运行不同规模的环境供电计算机系统时，若考虑这些热效应，可提升其能效、性能与可用性。