AskPablo: LED lights are amazing but expensive. By switching to them, will I save energy and money over the long run?

I would like to use LED lighting to replace all my existing lighting. Over the long run, will I be reducing energy consumption and pollution, and even saving money?
I have written a lot about the environmental benefits of compact fluorescent (CFL) light bulbs in the past, but never about LED light bulbs. LED stands for “light emitting diode” and is a semiconductor diode that emits a narrow frequency (color range) of light. To put it simply, think of it as a solar panel in reverse: Electricity goes in and light comes out. To answer your question, I requested LED light bulb samples from LED Waves, and received a high-power 7-watt LED bulb that emits 500 lumens, has an anticipated life span of 50,000 hours (that’s almost six years, 24 hours per day), and retails for $59.95. Since LEDs are directional — they emit light in a focused beam rather than in all directions, like a conventional light bulb — it is difficult to compare them exactly to CFLs or conventional incandescent light bulbs. But I will try to provide a comparison of their light output, energy consumption and cost-effectiveness.
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