Bitcoin Energy Consumption Index
You can't compare Bitcoin to Visa. Visa is merely a payment sytem -- a means of transfer of money that already exists. Visa is not money.<p>Bitcoin however <i>is</i> money. As well as being a payment system.<p>The correct comparison would be to compare the cost of Bitcoin to U.S. dollars or gold.  Gold requires hundreds of dollars per ounce and untold energy to extract. U.S. dollars require the existence of a powerful economy and trillion dollar military to keep the currency secure and desirable.