|Illustration from the Watronix website|
Having a Friday evening pint with one of my colleagues, Mark W, and randomly asking him what he is doing, I discovered he is an expert on ThermoElectric Heat Pumps - using the Peltier Effect. Used in the right way, similar devices can convert a heat difference into electrical power, rather like a motor becoming a dynamo.
Wiki information HP
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Before you or I get too excited, let's look further - I have also discovered that these are very small - from a few millimetres to a postage stamp, and the largest about the size of a playing card - and quite expensive. They have only about half the COP of a vapour compression heat pump like the one we are using, even if they could be scaled up enough to heat a house. There is also no set way to deliver or extract the heat or coolth, and how to group them.
One of the areas of Mark's research is to work out ways of doing this. Usually, a heat sink is fixed to one side and the other side is cool, to cool the interior of a piece of electronic equipment, perhaps. So this could be used for heating, if a fast moving water jacket (ground loop) was on the cold side side and a slow moving water jacket (heating circuit) was on the other. You would need an awful lot of playing cards to heat a house... :)