Even in the era of the compact fluorescent and rapidly-emerging LED lamps, a picture of Edison's screw-base A lamp is a near universally recognized symbol of someone having a bright idea. And although it is less than half as efficient as a compact fluorescent or LED, the incandescent lamp is far from the worst idea ever used to provide illumination for human activities.

That dubious honor goes to whale oil, the pursuit of which nearly extinguished the gray, bowhead and right whale species. These largest of mammals were only saved in the late 1800s by the emergence of, that's right, petroleum kerosene, which finally became a less expensive way to keep Jack the Ripper off the streets at night.

But compared to the energy efficiency and environmental impact of oil lamps, incandescents look like 10th generation LEDs, and oil was about five to seven times more efficient in terms of light output per unit of energy than candles. The best LEDs approach 90 lumens per watt and soon are expected to surpass the ~100 lumens/watt of the best fluorescent systems.

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