Last month, the social-media giant Facebook announced plans to build a new data center near Odense, Denmark. The expansion of server capacity was needed, the company said, to support "richer content" such as live-streaming and virtual reality.

The Facebook executive who made a public announcement of the decision (live-streamed, of course), noted that the new facility would have the "smallest footprint possible" and be "powered by 100 percent clean and renewable energy." Well, not exactly.