Not correct, though people say this very often.

"Backing" when talking about a currency has a very specific, important meaning. It means that some party has promised to redeem that currency for some other good of value. Backing requires a backer, in other words. It requires someone's promise to back Item A with Item B. This is how paper money can have real value, because if it's backed by a government or bank or corp that will give you gold/silver for it, then it has that same value by proxy. That's backing.

Bitcoin is not backed by anything, nor anyone. It is a resource, a commodity, a good in and of itself.

The cost of electricity/equipment does not back Bitcoin whatsoever, just as the cost of dredging deep-sea mud from the ocean floor doesn't back the price of this mud on the open market.