batteries - How could have Banksy kept an RF receiver running for 12 years?

I'm talking about Banksy's "Girl with balloon" painting that shredded itself at auction.

I think the general consensus is that he didn't, and that it was set up before the auction (or a couple years ago, not 12 years). But lets say he did, how could he have made it keep its power for that long? What sorts of RF receivers run on such low power? What batteries can withstand a 12 year low-but-constant-load life?