https://aceee.org/files/proceedings/2012/data/papers/0193-00...
It's from 2012 and cites numbers from as long ago as 2009 to determine normalized energy intensity. It also combines different numbers in a way that mean you can't estimate how much energy is saved by downloading a gigabyte to local storage instead of repeatedly streaming it. The single largest energy segment in their estimate is actually desktop computers! And it counts the energy used by CPU-intensive scripts along with the energy required by actual data transfer.
Sanity check: Cisco estimates "busy hour" internet traffic at around 3 petabits per second in 2019.
https://www.cisco.com/c/en/us/solutions/collateral/service-p...
If it took 5 kWh/GB for data transfer during that busy hour, corresponding peak hour electricity use would be in excess of 6.5 terawatts. But that's more electricity than the world can generate in any given hour.