notes: In Earth: The Operators' Manual, Richard Alley gives this example: To get light, we started by burning wood, which produces a lot more heat than light. Then we progressed to candles, to kerosene, to incandescent bulbs, to CFLs and now LEDs. Each technological advance produced more light and less waste heat. The ultimate efficiency in producing light without heat? Certain glow worms found in caves.
Bite Source: ; Richard Alley in Earth: The Operators' Manual. variation: Joe Romm, Climate Progress