Over the last several years, the electric utility markets have seen significant changes in the mix of generation supporting the grid. In particular, traditional generating forms such as coal, nuclear, and even natural gas are being replaced by intermittent generation sources such as wind and solar. Because of the increasing penetration of these intermittent sources, and their lack of controlled dispatchability, other fast-acting energy sources are becoming even more valuable in balancing supply and demand. This is one reason why utilities are increasingly providing financial incentives to their customers to more closely balance real-time supply and demand. Due to their generous capacity of underused UPS batteries, data centers are a prime candidate to take advantage of these incentives. In this paper, we describe approaches data center operators can use to monetize their UPS energy storage and explain the modes of UPS operation required for each method.