The incandescent light bulb was invented in 1879. It has served us well for the last 134 years. But as energy demands rise and concern over green house and climate change grows, a challenger has risen—the LED light bulbs. In 2011 the United States consumed 461 billion kilowatt-hours of electricity just to keep the lights on. Switching to energy efficient LED lights could reduce that number by as much as 90 percent, which would save trillions of dollars annually and dramatically decrease green house gas emissions. The Light Bulb Showdown series demonstrates the en...