Compact fluorescent bulbs that produce light equivalent to 100-watt bulbs have been available for a few years and cost as little as $4 each.LEDs are small chips that produce light when current passes through them. In their red and green incarnations, they've been around for decades. Technical breakthroughs in the 90s allowed the manufacture of chips that produce white light. LED bulbs equivalent to 60-watt bulbs have been available for a few years and now cost around $25 each. The problem with making brighter models is that while LEDs produce less heat than regular bulbs, the heat they do create shortens the lifespan and reduces the efficiency of the chips. Cramming a dozen chips together in a tight bulb-shaped package that fits in today's lamps and sockets makes the heat problem worse, and the brighter the bulb, the more heat is produced. LED bulbs have large, finned metal collars to radiate the heat.