It's nigh on impossible to know exactly how much energy is being used, but cryptocurrency tracking site Digiconomist is the source of one oft-cited estimate. According to its Bitcoin Energy Consumption Index, the network of computers that verify bitcoin transactions draw 3.4 Gigawatts (GW) ?" a single watt is a joule per second, and your laptop probably probably uses about 60W. That 3.4GW adds up to 30.1 terrawatt hours (TWh) per year of energy ?" that doesn't mean that much energy is used per hour, every hour, but is instead a measurement that equates to the amount of work those 30 terrawatts would do over an hour. In this case, that 30.1TWh is equivalent to the energy used by the entire nation of Morocco annually. Some dispute this figure. Fervently. Oscar Lafarga, co-founder from cryptocurrency consultant and developer SetOcean, reckons the real answer is likely half as much. In Bitcoin Magazine, Marc Bevand suggests it's likely lower still at between 470MW and 540MW.