Much has been said about the potential for cryptocurrencies to replace mainstream card payments in the future. Let's look at some simple figures on this.
World Payments Report data indicates that there are over 400 Billion non-cash transactions annually.
(Source : https://www.worldpaymentsreport.com/download)
A conservative estimate for the energy consumed in a single Bitcoin transaction is 133kWh (kilo-Watt-hours) . One Visa card transaction has been estimated at using 10Wh .
So, to replace non-cash with Bitcoin, there would need to be an energy pool of 53,200 TWh. Compare this to Google's annual power consumption of around 6 TWh.
World Electrical Energy Production currently is around 25,000 TWh 
(Source : https://yearbook.enerdata.net/electricity/world-electricity-production-statistics.html)
So, we would need double the total energy production of the globe to support Bitcoin as an alternative to non-cash transactions.