Originally Posted by ranger_one
SIZE. 500,000 square feet is huge for a data center. Most data centers have standardized on ultra-high-density blade servers; even though Apple doesn't build their own blade product, they can fit 42 of their 1U Xserves in a single data center rack that takes up less than a square meter. Huge multi-national corporations can run all their data center operations out of facilities as small as 2,000 square feet. Even with "modules" for SAN storage, robotic backup silos, power backup units, staging labs and workspaces for people it's really unlikely Apple would run out of space in a 500,000 sf facility anytime soon, especially considering that server footprints are shrinking.
PARKING LOT/EXPANSION AREA. I believe this is simply the construction parking and staging area, which is now likely being lightly terraformed with plantings, etc. to lessen the environmental impact. This is not a long-term parking lot; data centers like this typically would be staffed with fewer than 30 employees per shift. Even adding some "burst" parking capacity for emergencies, special projects, etc. it's unlikely they would ever need more parking than what currently surrounds the facility. This isn't a Wal-Mart, it's a data center.
TANKS. I believe those silos out back are the diesel tanks for the backup generators. They are large, but realize that high computing density requires high power density. Apple's Xserves, if I recall correctly, could theoretically eat up 168 amps per rack @240V at 100% density. It would take some monstrous generator capacity to power a 500,000 sf data center of these machines. Data centers typically have enough diesel on-hand to power the entire facility for 3-5 days (I worked in one that had two weeks of capacity), with contracts to provide continuous refueling to keep it running indefinitely. Why two? Redundancy-- everything in a DC is redundant. Power typically comes from two different substations into two different locations on the building, Internet connectivity normally comes from two different carriers (at least) into two ingress points on the building, etc. AC units, power backup units, etc. all include hot spares to take over and maintain capacity in the event of a multi-unit failure. Serious enterprise-class data centers are built to withstand terrorist attacks.
POWER LINES. They're underground; you wouldn't want to give a guy with a stick of dynamite the ability to take down an above-ground power line and blackout your data center. It's not for aesthetics, it's for reliability.
ROOF: This is a cool roof. It's all-white to minimize thermal load on a data center that probably needs to be cooled to 60 degrees despite tens of thousands of running servers. Yes, adding solar would have been cool but it's not practical. Remember that the sun probably puts out about 600 watts per square meter on a clear day (that's a guess for this latitude). The best solar cells are only about 20% efficient now, so (rough estimate) you'd need about 3 square meters to offset the average wattage of just one of the 42 x-serves in a single rack. And that's assuming 100% sun load (no clouds). Also, data centers try to be as anonymous as possible so you'll likely not see any logos or signs. Most people work next to data centers for years without even realizing what they are.
Seriously, all someone needs to do is check the permits with the municipality to find out what's really going on. As a rumor, this is interesting to debate but as a news story, it lacks any reasonable investigation.
UPDATE: MacRumors has a photo from the county that shows two buildings. An assumption is made that since the size was always pegged at 500,000 sf, it may be that the first building we see now is 250,000 sf and that the construction parking/staging area I referenced above could actually be for the second half of the 500,000 sf building.