Another example is to light up a candle, then use a peltier element and a heatsink to generate electricity. Then use that electricity to power a led. The outcom

Another example is to light up a candle, then use a peltier element and a heatsink to generate electricity. Then use that electricity to power a led. The outcome is that you have some of the candle light, but you will have a much more light from the led.