All told, experts say that extensive studies by electrical utilities and third parties show that installing underground power lines, especially high-voltage ones, can cost up to US$20 million per mile, which is about 10 to 20 times more than stringing them overhead.

Even pro-reliability watchdogs such as NERC don't advocate underground power.

"We push for a more reliable system, yes, but we do not as a general rule push for utilities to build underground lines rather than aerial transmission poles," said Johnson.

On the other side of the ledger, a dense underground power grid can be benefit data center operators by allowing them to tap into lines two or more times for redundancy's sake.

"That's the holy grail for data centers if you can do that," said Biggs, who said it helped his Jacksonville, Fla., facility achieve Tier 1 certification.