Standby TVs Waste Electricity, How About ACPI?

twitter asks: "There's power management and there's standby, do you know the difference? The BBC is running story on how much electricity is wasted by TV standby mode. Thanks to the very useful EnergyStar program, I'd be the one in seven who thought they were saving electricity, with the standby button. I've been very happy with APM and hibernation on laptops, and want to do something similar with the desktops I use. What's the state of APM / ACPI Wake-on-LAN for Linux these days?" Slashdot touched on this issue, earlier in the week, but that article was more on TVs, not on computer power saving technologies.

Comments

Convenience

[kestasjk]

If it's more convenient we'll keep on wasting energy. The worst part is the standby circuits use practically no power compared to the transformers, which waste far more energy as heat than the standby circuitry uses. There should be a seperate battery power source powering the suspend-mode circuitry, which lets current into the transformer to provide the power needed for normal operation.. But of course this would cost extra, and consumers wouldn't pay extra for it even if it saved money on power bills in the long run.

Re: Convenience

[David Horn]

Ignoring that fact adding a battery would probably use more energy in the manufacturing that it could possibly save, the point of the parent author was energy saving in general, not saving you money.

I don't know how many TVs there are in the US, and I also suspect that shutting down the transformers in a large set will save more than 2W. I'm going to guess at 5W saved, over 500 million TVs. That's 44kWh per TV per year saved.

In every TV, that's 2x10^10kWh of energy saved across the whole of the US. Those are wild guesses, but they're probably in the ballpark. I don't want to come across as a troll, but it highlights the fact that you think solely about yourself rather than the bigger picture.

I'm not a tree-hugger, but you only have to look out of the window to see all the energy being wasted (PCs / TVs left on, cars sitting in traffic jams etc. etc.). Like it or not, unless we go nuclear we're going to have a serious energy problem in 50-100 years time. I think we need to start changing attitudes now.

Re: Convenience

[alienw]

Actually, that's already how it's done, and that's exactly why a lot of power is wasted. A small, cheap transformer is usually a lot less efficient than a large one. A large transformer has thicker wire for the windings, so less resistive losses. It also has a higher-quality core, so there are fewer core losses. Of course, this is largely irrelevant, since the last time large transformers were used in consumer electronics was in the '70s. These days, almost all power supplies are switching types, whose efficiency is determined by their design and the quality of parts used. Since nobody really tries to optimize their efficiency, they can be extremely inefficient, and often very poorly designed. Most of them are made by Chinese companies who usually copy other companies' designs without even understanding how they work.

I think a law to mandate maximum standby power consumption (or, even better, incentives to minimize it as much as possible) can do quite a bit. Right now, it is simply not a factor in the design of equipment.

Re: Convenience

[alienw]

Actually, I don't think most modern TVs keep the tube warmed up. My TV takes the same time to turn on whether it's in standby mode or not. Nobody uses separate IR decoder chips, it's usually merged into the main ASIC and it's actually a microcontroller. If it's carefully optimized, it will draw about 0.3mA in sleep mode and a few milliamps when it runs. The real problem is the IR receiver (the ones I looked at draw 1-2mA), and more importantly the large relay which is supposed to switch on the main supply. It might be possible to solve this problem with something exotic, like a photo-triac, but it's definitely not simply a matter of putting in one capacitor.

Re:Why are "standby" and "sleep" functions needed?

[TeknoHog]

I don't understand why there should be hardware standby and sleep functions. The hardware should be provided with a means of reading and writing its entire state. When you power down, the contents of RAM and all the hardware state should get written to the hard drive. When you power up normally, instead of going through a lengthy boot process, it should read and restore the state the contents of RAM and the hardware state, and pick up where it left off.

Linux's software suspend does just this, see my other post here. Well, in fact you have to boot the kernel normally (to initialize hardware, etc.) but instead of a lengthy init, you get the restored state.