tannersfriend re: "We can see that replacing one copper cable by AOC the pure savings in energy are about 3430 USD/year per cable - neglecting the savings for cooling".

I wish this was correct, but I don't think so (I hope it is correct and I am wrong). Using the metrics provided by POET from the CC, I estimated ~ $8 energy savings per year per link (i.e. replace a Cu cable with a POET AOC). My estimate was to save ~ $800,000 per year for 100,000 cables (see link to post below). I think FJ said he had something similar with his calculations. There is likely more to this, including the extra savings for multiple channels. The savings is indeed significant, plus other benefits.

Also, if it was $3430 savings per year per cable, this would equate to 343 million dollars in savings for a data center with 100,000 cables, which I can't imagine is in the right order of magnitude. Not to mention 50% extra savings for cooling, so over 500 million (can't be).

POET estimated ~ 5W savings per link (excluding the savings with cooling), so in line with 10W savings from your reference. However, energy cost may be ~ $0.12 per kilowatt-hour, so for 10W or 0.01kW x $0.12 x 8760 hours per year = $10.51 per cable, so not sure where $3500 cost reduction in the reference comes from.

http://agoracom.com/ir/POETTechnologies/forums/discussion/topics/661466-dollar-savings-with-poet-in-a-data-center/messages/2075229#message