National Geographic : 2009 Mar
• FOLLOW UP | SAVING ENERGY PHOTO: TYRONE TURNER *THREE HOURS' DAILY USE AT AVERAGE U.S. RATES. BULB PRICES ARE APPROXIMATE. Incandescent 65 cents a bulb 15 years of electricity: $72.55* 1,000- to 2,000-hour life CFL $4 a bulb 15 years of electricity: $18.14 6,000- to 12,000-hour life LED $120 a bulb 15 years of electricity: $9.67 20,000- to 50,000-hour life Changing Bulbs The light-emitting diode (LED) looks like the eco-bulb of the future. With no filament, just a microchip, it uses significantly less energy than an incandescent. But the price is high and reviews are mixed. LED illumination can range from warm to what technology analyst Michael Kanellos calls "alien autopsy." The bulb casts its light in only one direction, which is fine for recessed lights and for spotlighting a specific area but could be a drawback in lamps or globes. In a few years, expect a cheaper, more versatile LED. Until then, experts recommend compact fluores- cents (CFLs) for most home use---with a note of caution. Their mercury content calls for disposal as hazardous waste. ---Linda Kulman The metal casing on some LEDs disperses heat into the air but keeps the light from shining in all directions.