Will Smart Outlets save power or Waste Money?

Last week I had a conversation with my favorite engineering friend Lee Devlin. Lee's articles have been featured numerous times here on the CleanTech Authority Network and he's the guy I turn to when I need advice about EE challenges. This time I was asking Lee about Vampire Power loss, which is a phenomenon that occurs in millions of homes nation wide in the US and other countries.

When you leave appliances plugged in they drain power or create heat which wastes power. I was wondering, aren't there smart outlets that stop the flow of energy for appliances when not in use? If so, how would these work and where can I get them? I know there are power strips that you can manually turn off, but what about a smart outlet that could be used in houses across the nation. I asked Lee if he knew how to build something like this or if it exists already. Maybe it would require an actual switch at the outlet or maybe it could be smart enough to figure it out on its own.

Below is an image taken from a recent National Geographic story we covered about saving energy at home, the bright red represents heat from the flow of electricity even though none of the chargers are being used. Take note that while this image is very dramatic in it's appearance, the actual power loss experienced may not be so.

Lee responded to my question with the following tips: There is a device called a Kill-A-Watt that will measure current draw on power cubes and that would help to determine whether leaving a charger connected is a cause for concern. It will measure down to a very low power consumption, about a watt. I have yet to find any modern chargers that consume much electricity when nothing is connected to them. My iPhone's power cube doesn't even register a watt until I plug in the iPhone. Then it registers about 4 watts while it's charging and 0 watts after the phone is charged. The iPhone's battery has a capacity of 7 W-h, which is about .07 cents worth of electricity. Even if I drained and charged it every day, it would use only 25 cents in electricity per year. So if a charger left plugged in for a year drew another 25 cents in electricity, it would be hard to justify spending very much to prevent it.

Suppose there was a device that cost $25 that sensed whether any DC current was flowing from the charger, and if not, turned off the current at the wall outlet. It would take 100 years of energy savings to pay for itself, provided it didn't consume electricity. But it would need to use electricity, and therefore would likely create a net loss of energy overall.

Generally speaking, something that is left on all the time but draws less than a watt isn't a major concern. A one watt load over the course of a month adds about $.07 to your electric bill.  Having said that, there are plenty of items that even when they appear to be turned off will draw 5 to 10 watts or more, and these things can add up on your bill. Over the course of a month, a persistent 15 watt load will add about  $1 to your monthly electric bill. That's the best place to direct one's attention when looking to save energy.

Regarding the image above, images from IR cameras can be very misleading and should not be used as a way to estimate relative power consumption. An IR camera is self-adjusting so that it can read even the slightest change in temperature variation in its view and then it adjusts its color range to achieve the maximum color differential. This often gives the false impression that there is a wide variation of temperatures and a large amount of heat being generated. However, it may only be a few degrees of temperature variation even though it shows colors going all the way from blue to red, causing people to think that some parts of the picture are below freezing and other parts are 'red hot'. A small temperature differential can be achieved with just milliwatts of power. Rather than using an $2500 IR camera, a Kill-A-Watt, which costs $18 at newegg.com, is much more useful to show where in your household you can achieve energy savings. In general, it makes sense to attack persistent loads that are more than 5 watts, and ignore anything less than 1 watt, because those loads will make little difference in the grand scheme of things. I know that every little bit adds up, but the best use of your time is to go after the big offenders, and you'll be surprised where you'll find them. My very expensive Bose Wave clock radio draws 10 watts continuously whether it's playing music or not, whereas my el-cheapo clock radios, that essentially perform the same function, all draw less than 1 watt.

If you don't have a Kill-A-Watt, I would highly recommend you get one.  They are very valuable in helping sort out where your electricity is being wasted, or not being wasted, whatever the case may be.

The best kind of smart outlet I see in the future will be the kind that is connected to a smart grid. This grid will monitor use and charging so that appliances can actually store electricity and act as a back up power source, a sort of distributed battery... Stay tuned for more on this topic and check out EV Authority for more battery related news and stories.