Ouch! Facebook was met with acclaim when it decided to build it’s own super-efficient data center in Prineville, Oregon — a departure for the serial lessee — but the mood soured a bit when it was learned that coal would be a source of the energy used at the facility. Facebook finally responded, downplaying the sourcing issue and touting the energy efficiency angle. If only it were that simple. For more insight, check out Derrick Harris’ recent Weekly Update, which deals with the very issue that’s emerged as the latest thorn in the social networking giant’s side.