At home, my Samsung laser-printer uses 15W during standby. So, a few years back, in order to save power, I put it on a USB-controlled power-plug. Pretty soon I added a tiny script that would query cups if a print-job was queued and would switch the printer on and afterwards off again. It turned out to be a pretty effective power saving measure.
Our two very big and reliable printers at realraum were even more power hungry, so I wanted to to something similar for the space.
Using the hardware I had on hand, I cobbled together the following:
* A BeagleBone Green to act as cups print-server and to run the python scripts.
* An empty 230V power-plug case, housing a 5V power-supply (for the BB) and a small opto-coupler isolated relay to switch the plug.
* A second power-plug case with a second small opto-coupler isolated relay.
While there is a lot of room for optimization, like a leaner BeagleBone image and better housing for the power-plugs, printing- and power-saving-wise it works very well.
As always you can find our code on Github. Stay tuned for updates.