Energy storage in data centers has mainly been used as devices to backup generators during power outages. Recently there has been a growing interest in using energy storage devices to actively shape power consumption in data centers to reduce their skyrocketing electricity bills. In this paper, we consider using energy storage in data centers for two applications in a joint fashion: reducing peak demand charges and enabling data centers to participate in regulation markets. We develop an optimization framework that captures the cost of electricity degradation of energy storage devices, as well as the benefit from regulation markets. Under this framework, using real data Microsoft data center traces and PJM regulation signals, we show the electricity bill of a data center can be reduced by up to 20%. Furthermore, we demonstrate that the saving from joint optimization can be even larger than the  sum  of individually optimizing each component. We quantify the particular aspects of data center load profiles that lead to this  superlinear  gain. Compared to prior works that consider using energy storage devices for each single application alone, our results suggest that energy storage in data centers can have much larger impacts than previously thought possible.
['Yuanyuan Shi', 'Bolun Xu', 'Baosen Zhang', 'Di Wang']
Leveraging energy storage to optimize data center electricity cost in emerging power markets