Bitcoin has been criticized for the amount of electricity consumed by mining. As of 2015, The Economist estimated that even if all miners used modern facilities, the combined electricity consumption would be 166.7 megawatts (1.46 terawatt-hours per year).At the end of 2017, the global bitcoin mining activity was estimated to consume between one and four gigawatts of electricity. By 2018, bitcoin was estimated by Joule to use 2.55 GW, while Environmental Science & Technology estimated bitcoin to consume 3.572 GW (31.29 TWh for the year). In July 2019 BBC reported bitcoin consumes about 7 gigawatts, 0.2% of the global total, or equivalent to that of Switzerland. A 2021 estimate from the University of Cambridge suggests bitcoin consumes more than 178 (TWh) annually, ranking it in the top 30 energy consumers if it were a country.

According to politico , even the high-end estimates of bitcoin's total consumption levels amount to only about 6% of the total power consumed by the global banking sector, and even if bitcoin's consumption levels increased 100 fold from today's levels, bitcoin's consumption would still only amount to about 2% of global power consumption.

To lower the costs, bitcoin miners have set up in places like Iceland where geothermal energy is cheap and cooling Arctic air is free.  Bitcoin miners are known to use hydroelectric power in Tibet, Quebec, Washington (state), and Austria to reduce electricity costs. Miners are attracted to suppliers such as hydro quebec that have energy surpluses. According to a University of Cambridge study, much of bitcoin mining is done in China, where electricity is subsidized by the government ....