An average block has something like 2500 transactions in it. It means that there is about 1-2 transactions per second. Bitcoin network is running at 100 million

An average block has something like 2500 transactions in it. It means that there is about 1-2 transactions per second. Bitcoin network is running at 100 million TH/s. Modern mining hardware does 10 GH/Joule = 10^10 H/J, so 100 million TH = 10^8 * 10^12 H = 10^20 H is 10^20/10^10 = 10^10 Joules. 1 kWh is 3.6 * 10^6 joules, so 10^10 Joules is something like 3 * 10^3 kWh, so 3 MWh. One ton of coal produces something like 2 MWh. So yeah, assuming some of the electricity is not coal, the numbers do add up.