A USB power hub with an electricity consumption display can be used to power a Raspberry Pi 4.
Many USB hubs have 6, 9 or more ports on them. Plug in six Raspberry Pi 4 computers, load the Lynx software on them and wait 12 hours. Look at the display to see the real time energy consumption of the devices. The reason we do the experiment with six Pi’s instead of one, is to average out hardware and software variance that might occur. At the time of this writing, six Raspberry Pi 4 computers consume the same amount of electricity as a ~30 watt light bulb. It is now possible to easily and inexpensively replicate this test and extrapolate annual costs for a much larger global Lynx network.