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I think there are two issues here, one future energy cost predictability which is much easier to manage when you own the source of your energy and, two, green energy. It has certainly become more common for large companies to include environmentally friendly power sources as part of their planning for new data centers. As more companies increase their environmental awareness, whether because they actually care about it or for marketing reasons, there are more and more incentives for data centers to be LEED Gold and/or EPA Energy Star certified compliant. Of course, there is always a concern for energy expenses, and now that renewables are getting close to traditional sources of power in terms of cost, you will see more and more companies embracing green energy. This can also be an important consideration for companies that are in markets where carbon offset credits are an issue.