The next few years will bring widespread awareness of the environment's impact—especially energy costs—associated with data storage. Already several regulations and initiatives—for example, restriction of hazardous substances (ROHS), waste from electrical and electronic equipment (WEEE) and Energy Star—affect manufacturers of storage components or computers. There are also some innovative storage technologies especially targeted towards energy conservation including a massive array of idle disks (MAID), along with the well-known alternatives of removable storage like tape and optical. Several vendors have also begun to offer data on power use, energy consumption and cooling loads in response to competitive pressures from other vendors and customers. Some vendors and consultants are offering energy modeling as part of their total cost of ownership (TCO) analysis, either for competitive reasons or as part of their professional services portfolio. This presentation will quickly review basic engineering topics relevant to understanding "Green," including stuff you may have successfully avoided, such as environmental chemistry; thermodynamics; energy vs. power; and computational and storage density, as well as the resulting energy and cooling issues. Conceptual models sufficient to understand or even develop energy budgets will be taught. All of this will converge on a basic model for TCO that includes energy modeling. This session has been brought to you by the SNIA Green Storage Initiative.