Energy costs for conducting compute tasks at diverse data center sites are determined and are then used to route such tasks in a most efficient manner. A given compute task is first evaluated to predict potential energy consumption. The most favorable real-time energy costs for the task are determined at the various data center sites. The likely time period of the more favorable cost as well as the stability at the data center are additional factors. A workload dispatcher then forwards the selected compute task to the data center having the most favorable real-time energy costs. Among the criteria used to select the most favorable data center is a determination that the proposed center presently has the resources for the task. A stabilizer is utilized to balance the workload among the data centers. A computer implementation for performing the various steps of the cost determination and allocation is also described.