Bitcoin's annual electricity consumption is estimated to be 51.09 terawatt hours, which is more than many countries. This high energy use is due to bitcoin mining, which secures the network through proof-of-work but requires vast computing power. If bitcoin was a country, its electricity consumption would be similar to countries like Iraq or Singapore. However, each bitcoin transaction uses much more energy than traditional payment networks like Visa. Alternative consensus mechanisms like proof-of-stake promise to be far more energy efficient.