CFLs vs. Incandescents: Less money, energy, and…mercury?
Based on the emission rate for Oregon's energy generation, the use of CFLs represents a significantly smaller source of mercury compared to incandescent bulbs.
Compared to traditional incandescent light bulbs, compact fluorescent light bulbs (CFLs) save money and energy. A quick comparison between a 100 watt incandescent bulb and a similar 23 watt CFL illustrates these savings.
| 100W Incandescent (1,351 lumens) |
23W CFL (1,278 lumens) |
|
|---|---|---|
| Approximate purchase price | $0.75 | $4.00 |
| Life of the lamp | 750 hours |
10,000 hours |
| Number of lamps needed | ~13 |
1 |
| Total cost of lamps (cost * number) |
$9.75 |
$4.00 |
| Total cost of electricity ($0.05 / kWh) |
1000 kWh = $50.00 | 230 kWh = $11.50 |
| Total cost over 10,000 hours | $59.75 |
$15.50 |
Using less energy also provides environmental benefits. The energy savings from using CFLs results in lower emissions of air pollutants from power plants. These emissions include carbon dioxide (CO2), a greenhouse gas, and nitrogen oxides, which cause smog. In addition, they can reduce emissions of mercury associated with coal-fired power plants.
CFLs contain a relatively small amount of mercury. No mercury is released during their operation. If a bulb is broken, clean up is not dangerous. Currently, mercury is an irreplaceable element of CFLs that has no substitute. According to the U.S. EPA, the average CFL contains approximately 4 milligrams (mg) of mercury. [PDF] This is significantly less than you would find in old thermometers or thermostats. If the CFL is sent to a landfill, approximately 14% of that mercury is released to the air and water if the bulb is broken.
In Oregon, many residential customers get about 40% of their power from coal-fired power plants. Some may get up to 75%. Purchasing renewable energy can reduce or eliminate mercury emissions associated with burning coal for electricity generation. Burning coal to generate electricity emits approximately 21.77 mg of mercury per megawatt hour.
Based on this emission rate, the use of CFLs represents a significantly smaller source of mercury compared to incandescent bulbs. Based on a lifespan of 10,000 hours of use for a CFL, they emit less than a third of the mercury associated with incandescent bulbs used for the same time period.
