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"I was told it could be a little better than an incandescent bulb, but that was about it," said General Electric engineer Ed Hammer, who invented the spiral compact fluorescent lamp (CFL) in the mid-70s. In fact, his invention uses just 25% of the power of an old-fashioned, incandescent bulb and lasts around ten times longer.

Today CFLs are standard in homes and offices around the world and many countries have phased out incandescent bulbs, including an out-right legal ban in Argentina. If the electricity that lights the bulb is created from coal, then the invention has saved 500 pounds (227kg) of coal per bulb.