Instead of worrying about how soon bitcoin will melt the polar ice caps, though, it’s worth considering how much energy might be saved. Bitcoin miners will consume an estimated 8.27 terawatt-hours per year. That might sound like a lot, but it’s actually less than an eighth of what U.S. data centers use, 1  and only about 0.21 percent of total U.S. consumption. It also compares favorably to the currencies and commodities that bitcoin could help replace: Global production of cash and coins consumes an estimated 11 terawatt-hours per year, while gold mining burns the equivalent of 132 terawatt-hours. And that doesn’t include armored trucks, bank vaults, security systems and such. So in the right context, bitcoin is positively green.