Light Efficiency

The traditional incandescent bulb was invented by Edison more than 150 years ago. It was a direct move from burning candles to “burning” a carbon filament with electricity. The technology is extremely inefficient. Incandescent bulbs produce only 8 to 12 lumens per watt. The majority of energy is dissipated as heat, the reason why bulbs are so hot. In fact, with all the losses during the production at the power plant and the transportation of electrify, only 1% of the energy originally available to produce electricity (Coal, Gas, Water head) arrives as useful photons. If electricity is produces with coal and considering that one megawatt of coal produces 1 tonne of CO2, a 100-watt bulb “produces” _ kg of CO2 per hour – or about one tonne after a couple of years. Compact Fluorescent Lamps (CFL) are 3 to 4 times more energy efficient that incandescent bulbs – about 80 to 100 lumens per watt. They last 13 times longer than traditional lamps. Finally, LED ( Light Emitting Diodes) produce 30 to 40 Lumens per watt, about half less efficient than CFL. They have however a much longer life span than CFL.
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