Douwe Osinga's Blog: Gas heaters with more than 100% efficiency

Tuesday, May 13, 2003

Gas heaters with more than 100% efficiency

Of course this is nothing new, but today was the first day I heard about it. Gas heating with an efficiency of more then 100%. It seems improbable. You burn the gas, make heat and without miss, some of this heat escapes to the outside world. The heat you keep is always less then 100% and the best gas heaters are indeed around 90% efficient.

But you can beat this. Imagine a refrigerator with the door removed and the gap to the outside of the house. All the energy that the fridge needs is converted into warmth and kept inside the house. But the machine also produces coldness, which is blown outside. Since you cannot make something colder, without making something else hotter, the house should be warming up. Ergo, the house is getting warmer then the solely the energy used for the refrigerator.

This works because although energy is energy and you cannot create or lose it, some energy is of higher quality than others. You cannot collect small differences of temperatures and put them together to create a big difference of temperature, without sacrificing some higher quality energy in the process. But gas represents high quality energy and you can use this high quality energy to do just that: use a warmth pump to collect small differences in temperature to make the temperature of the house nicer.

The interesting thing is that somebody, Co van Liere, succeeded in converting this idea into an actually working machine. Gas is used to make a bit of warmth and some electricity. The electricity is used for the warmth pump. Theoretically this could make a gas heater over four times as efficient. Currently a 100% increase of efficiency is possible. Clever.