Overlay energy circle formation for cloud data centers with renewable energy futures contracts

Cloud data centers are significant players in the electricity market due to their high energy consumption. It is highly desired to operate cloud data centers on only renewable energy such as solar, wind or tidal to reduce their cost and emissions. In the literature, utilization of renewable energy is maximized through workload migration towards data centers that are forecasted to have surplus renewable energy which is also known as “follow the sun chase the wind” approach. In practice, it is rather difficult and unrealistic to shift workloads based on instantaneous output of renewable generation. Generally forecast tools are used which can only provide a rough estimate of the generation capacity. In this paper, we use a more realistic approach and propose an overlay architecture to form energy circles of cloud data centers depending on their load and renewable energy futures contracts. A futures contract is an electricity purchase agreement between the data center operator and the renewable energy generator to purchase electricity in the future with today´s price. Futures contracts are electricity market mechanisms that reduce the cost related risks for both parties and are seen as tools to scale-up renewable generation. On the other hand, fluctuating loads of cloud data centers may leave some contract capacity left unused or exceed the capacity. In this case, electricity will be purchased at current market price from the renewable generator or the utility grid where in both cases the electricity bill will increase. Hence, a mechanism to utilize the unused capacity in the contracts of peer data centers and shifting workloads towards available capacity can reduce bills as well as increase the utilization of renewable energy. Our proposed energy circles approach aims to group cloud data centers to achieve those goals.