Power Management 102: Carbon

Thursday, April 7, 2011 |
You might have noticed in my previous "Power Management 101" entry that there was a whole section of the spreadsheet I didn't even mention: "Pounds of Carbon."

Everyone likes saving money and 101 showed how you can do just that.  Beyond saving money, though is another important savings; reducing carbon emissions (e.g., from the power generated to run our computers) will help reduce the impact of global climate change.  The scientific evidence of humankind's role in accelerating that change and, so, our potential role in reducing it is broad and well established.

So, how much can your use of power management on your PC actually reduce carbon emissions?  Let's look at the spreadsheet again:


This means that, using the examples of my LCD Widescreen Monitor and Graphics Laptop (and assuming the average US energy cost and carbon load from electricity generation):
  • Instead of leaving it on with the computer turned off, just turn off a similar monitor for the eight hours you're asleep and you'll save:
    • US$9.01 per year in electricity cost just from this one device
    • 104.12 pounds of CO2 emissions per year from this monitor
  • Instead of leaving your laptop on and Idle while you're away for means two hours each day, Suspend the laptop and avoid:
    • US$0.95 per year on electricity
    • 11.01 pounds of CO2 emissions per year
  • Even better, Hibernate (or turn off) that nifty graphics laptop while you're off eating and save:
    • US$2.60 per year on your electricity bill
    • 30.03 pounds of C02 emissions per year

If you and 99 of your online gaming friends all do the same, the combined savings add up to more than 3 tons of C02 per year!

Finally think of getting some sleep, for you and for your computing setup. Just turn off your nice external monitor and that graphically powerful gaming laptop while you get a good, healthy eight hours of sleep each night of the year.  Do that and your savings are:
$US19.41 per year in reduced cost of electricity
224.26 pounds of CO2 emissions per year that never happen thanks to you.

If you and 999 of your family, friends, neighbors, and co-workers all do the same then your social network will save more than 100 tons of CO2 per year!

Idle computers / Cost much, do little; change now / Sleep for big savings.

3 comments:

Niebylski said...

Nice followup to the original report - one very minor nitpick: you have a column heading of "Pounds of Carbon" that should say "Pounds of CO2" (or you just need to multiply those cells by 12/44 (ratio of molecular weights of C to CO2)

It might also be worth calculating the GHG/CO2 equivalences of the NOx emissions associated with the avoided power use. The EPA's GHG equivalences calculator is a good tool for that:
http://goo.gl/CF9u

It looks like the figure you used for the lbs CO2/kWh may be the national average from the eGRID 2007 report? That sounds like its about right - I'm downloading the 2010 updated report now, but I don't think the emissions rates will have changed very dramatically.

While 1.34 is the average figure, regional rates can depart pretty significantly from that average. If you're getting your power in nat. gas and nuclear rich New England, then the CO2 rate is more like 0.9. But, if you're in the Rockies or the northern Great Plains, I think the figure is about double that - around 1.8.
Here's the link to the Summary tables for the most recetn eGrid report:
http://goo.gl/KLcBW

George in Oregon said...

Thanks for the comment. Agreed on the heading more correctly being C02. Yes, I used the national average from the 2007 report (what I had available at the time) and the regional variations are quite notable. As I'm in the Pacific Northwest, my local numbers tend toward the low-end of the range and, as you've noted, areas supplied primarily by coal are significantly higher.

I'll check out the latest report. Thanks for the link!

Unknown said...

Its quite true that we hardly think of saving carbon emissions to the environment.The table by Mr.George Goodman clearly shows the quantity of carbon released in relation to the power used on PC.
sap upgrade

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