The process of trying to come up with the right nonce that will generate the target hash is basically trial and error—in the manner of a thief trying random passwords to hack yours—and can take trillions of tries. With hundreds of thousands or more computers churning out guesses, Bitcoin is thought to consume 707 kwH per transaction. In addition, the computers consume additional energy because they generate heat and need to be kept cool. And while it’s impossible to know exactly how much electricity Bitcoin uses because different computers and cooling systems have varying levels of energy efficiency, a University of Cambridge analysis estimated that bitcoin mining consumes 121.36 terawatt hours a year. This is more than all of Argentina consumes, or more than the consumption of Google, Apple, Facebook and Microsoft combined.