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.

4 thoughts on “How much coal does it take to run a light bulb?

  1. Try to understand this, lighting makes up about 6% of the entire draw on the grid. Power gens have to keep a certain amount of reserve on the grid to avoid brownouts and spikes, and for emergencies. That never changes. Removing incans will do NOTHING toward reducing the draw on the grid,and on top of the fact that most lighting is used on the off peak hours. So, please explain to me how something that has so little effect, is really going to shut down power plants? Especially when say, during the hot summer months, pwr gens ramp up to handle a/c, but cut back during the evenings, only to ramp up again the next day? The logic is just not there.

    On the mercury issue, each bulb contains about as much mercury as the dot at hte end of this sentence. Multiply that hundreds of times for the bulbs that won’t be recycled, then you do have a environmental nightmare.

  2. I’m not sure anyone’s claimed that switching to more efficient light bulbs alone is going to shut down power plants.

  3. So, Paladin, you believe we should do nothing to reduce the amount of carbon we dump? Let our children deal with the disastrous conditions coming from global warming?
    And I agree that CFL bulbs not recycled are a hazard; we should require recycling for them and a lot of worse things than CFL bulbs, but that is another debate.

  4. Paladin, you are incorrect. Burning coal, produces far more mercury than putting every single cfl in a landfill, fact.

    A 23 watt CFL, is more than 75% efficient than a 100 watt incandescent, they both produce the same lumen. Therefore the 6% energy needed for lighting would decrease to 1.5%! Are you thinking clearly? Or pipe dreaming?