Green Me has come down with a not so nice virus. Thankfully, my husband has been playing with electricity for the last week and was happy to write the following guest post.

Every month the electricity bill arrives and I’m presented with a stark figure in kilowatt-hours (kWh) representing the household usage for the past 30 days. It varies seasonally and a little due to our conscious efforts, but while I’ve had an idea as to what contributes to this figure there’s been no dollar figure or environmental cost attached to the choices we make on a daily basis. Should I turn my computer off or is standby ok? Does leaving the stereo on for some background music substantially impact our energy consumption? (It turns out that our stereo uses less than a 60 Watt light bulb.)

For the past week I’ve had the fortune of borrowing a handy device called a Kill-a-Watt from one of our friends. If you’ve never played with one I highly recommend tracking a device down and conducting a mini (electrical) energy audit of your home. Unfortunately you’ll be limited to devices with a plug on a 15 Amp circuit, but that covers your lamps, stereo, computers, phones, and a myriad of other small power leeching devices in your home. With a little simple math you can figure out how much those devices are costing you and what is spewed into the environment to generate that power. That shiny new gadget may only be $9.99 on sale at Target, but what does it really cost after a year of being plugged in?

As a simple example, say your prototypical gadget uses 10W (0.01kW) of power and it’s always plugged in while dutifully generating negative ions or whatever it does. Over a year it would consume:

0.01kW x 24hrs x 7 days_per_week x 52 weeks/year = 87.36kWh

Based on the national average of $0.104/kWh for 2006, its power usage will cost you in the neighborhood of:

87.36kWh x $0.104 per kWh = $9.08/year

Your $10 gadget has now nearly doubled in price after just the first year!

Now what about the environmental impact?

Using this chart provided by the National Resources Defense Council you may be able to find pounds of emissions per MWh of energy produced by your regional provider.

If you live in Colorado like our family, chances are you use Xcel Energy. According to the NRDC numbers averaged across all energy sources, the yearly emissions produced by your gadget are:

3.9 lbs/MWh * 87.36kWh/1000 = 0.34 lbs SO2

3.1 lbs/MWh * 87.36kWh/1000 = 0.27 lbs NOx

1717.7 lbs/MWh * 87.36kWh/1000 = 150.06 lbs CO2

Keep in mind that none of these figures include emissions produced in the manufacture or transport your gadget. Power is also lost in its distribution, so there is more overhead there. Given the monetary and environmental cost of such a small gadget, just think about what a whole household worth of them can do.

When it comes to wasting energy, it is often the small things that add up. So, my advice to you:

1) Be cognizant of your household total power usage. Understand your monthly bill, the quantities involved, and what they mean.

2) Measure specific devices and consider the impact beyond the dollar contribution to your monthly bills.

3) Unplug, recycle, and eliminate the purchase of wasteful electronics for yourself and others whenever possible.

And, last but not least, read-up on Vampire Power!