Reply #12: To give you a handle on the big picture, a little googling

[EST]

got me a number on total power production.

In 2003, approx 42,000,000,000,000-that's forty two thousand billion or forty two trillion--kilowatt hours used globally, about 25% used for lighting. Cool numbers to piddle around with. With new technology, intelligent street lighting, and intelligent design (URK!) reducing that number by half could reduce the shock of population explosion and concomitant global warming considerably.

It all becomes heat--generating, cooling, the light energy, itself, the heat produced by all the losses in the circuits and the lamps.

A horsepower is about three quarters of a kilowatt.

A human being puts out about as much heat as a 100 watt light bulb.