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IEEE Seeks For Ethernet To 'Go Green'
alphadogg submitted a piece at the NetworkWorld site about the IEEE's efforts to introduce energy efficiency to Ethernet use. The group's Energy Efficient Ethernet group is looking into methods by which standards can be tweaked to encourage power savings. Current plans include ways to make computers 'choosier' about what level of bandwidth they're using. Idle systems would only run at 10Mbps, while email might draw 100Mbs, and scale up to 1000Mbps for large downloads and streaming video. The group is planning to discuss changes to the Ethernet link and higher layers. No restrictions are planned for device manufacturers, although the article suggests some companies might try to use energy efficiency as a competitive advantage. The EEE group estimates some $450 million a year could be saved via the use of energy efficient Ethernet technology.
Just because it doesn't generate heat doesn't mean it isn't losing power. The energy wasted in relation to the power on the cable is probably quite high (DC doesn't travel well, that's why wall power is AC remember) compared to just wiring up wall sockets and using warts or switching PSUs.
:D
You're just transferring the wall-wart to another room though, and making the loss over the cable add to the power inefficiency. Imagine the extra airconditioning provision the room with the new site-wide AC-DC converter will need
PoE is a clever way to power devices that are in hard to power places (where you can wire a network using a thin cable but far away from a power socket) and keeps devices cheap (no need to do anything but DC-DC conversion from PoE to components) but it's not any better energy-efficiency-wise.
Can't this IEEE stuff they're talking about simply be built into drivers? I know my laptop ethernet (Intel) has the ability to scale down the ethernet speed when the battery is in use, or during standby and so on. Would it cause too much trouble to have the driver anticipate and schedule a renegotiation on a power source change or based on activity? Why would ethernet vendors need to be involved if it was simply a driver 'problem' - apart from having to write drivers that do it for their hardware (which most of them DO already).
Can't we have a sysctl or a sysfs tweak in Linux/BSD/whatever to demonstrate it and see if it even helps? Does networking hardware at the other end (for instance a 32-port Cisco switch) actually use less power if half it's ports are at 10mbit rather than 100mbit?
Can't we do this with wireless? 802.11b etc. already has power calibration built in but could it pull it back when the bandwidth requirement isn't so high, saving battery life and not polluting the airwaves with high powered chatter? My card uses the same transmit power whatever the state of the laptop is..
An idea I've always thought about is converting to DC supplies indoors. AC has an advantage in terms of long-distance transmission, but in this day and age a HUGE part of our electric use is in devices that require DC power. Hell, many of the things that run AC (like lights) can in fact run DC with nary a problem. It's always boggled my mind why we have a bajillion power bricks sitting around, each venting heat like mad converting AC/DC, when in fact we could have a much more efficient "main" transformer installed in the house that does it on a larger scale and feeds our devices directly.
I imagine this would be even more useful for heavy power using environments like server farms - imagine if you can do with the huge boxy PSUs in every single box and just have a unified DC power source that can FAR more efficient than what's in the average beige boxen.
It is a good idea; in fact it's such a good idea that people have been thinking about ways to try and implement it in datacenters for a while. Unfortunately one of the bigger problems is that most motherboards don't run off of a single voltage; they have +5, -5, +3.3, +12, and so on. There has been a push by some big server-farm operators, Google in particular, to encourage board makers to produce mobos that only require a single +12V supply, because then you could do exactly what you say: have a big AC to DC converter somewhere (probably running from a medium-voltage AC main) and then distribute the 12VDC around to the racks.
It was a Slashdot article back in September:
http://hardware.slashdot.org/article.pl?sid=06/09
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(DC doesn't travel well, that's why wall power is AC remember)
This is a very common misconception. Low voltages don't travel well because you need more current (i.e: amps) to carry the same amount of power and this requires bigger wires. The main reason your wall power is AC is because it's easier and cheaper to build transformers for AC that convert high voltages (for distribution) into low voltages (for usage).
DC is actually used in electrical distribution. It's known as HVDC and it's actually more efficient then AC because it doesn't have to contend with capacitance issues.
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We are the United States Government! We don't do that sort of thing.