How much coal does it take to run a light bulb?

A new infographic on (h/t Treehugger) calculates how much fuel (from various sources) it takes to power a light bulb for a year:

Click here for large version.

The calculations are based on running a 100-watt bulb 24 hours a day for a year, which very few people do. But it’s an interesting benchmark for comparing the relative efficiency of different bulbs. For instance, a 23-watt CFL puts out about the same amount of light as a 100-watt incandescent. Since it uses 23 percent as much energy, multiplying the outcomes by 0.23 gives us the results.

So, an equivalent CFL bulb would require 162 pounds of coal to run for a year. That’s still a lot of coal, but quite an improvement over the 714 pounds an incandescent would use.

That leads to another point about the light bulb “ban” that I wrote about last week: Mercury. In addition to the “ban” myth, other opposition to the law centers around the fact that CFL bulbs contain trace amounts of mercury.

Mike Wapner of Pike Research sent me a link over the weekend to his piece on the topic, in which he takes a Heritage Foundation op-ed to task for perpetuating the myth that CFLs pose a mercury hazard:

Yes, CFLs contain mercury, but “high levels” of mercury? High as compared to what? Analysis has shown that there’s less mercury in a CFL than would be released into the atmosphere by burning the coal to make the extra electricity that the incandescent bulbs use over the lifetime of the CFL.

Once again, in the great bulb debate, there’s a lot more heat being generated than light.

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