# Heat to energy

1. Jul 23, 2011

### Gabe21

Other that steam power, are there any efficient ways to convert heat to electrical energy

2. Jul 24, 2011

### jambaugh

The mechanism of converting heat to mechanical energy is called a heat engine. There are various types, e.g. the http://en.wikipedia.org/wiki/Sterling_engine" [Broken].

We can use the term heat engine to mean conversion of heat to ANY form of useful energy be it mechanical, electrical or some other form.

The http://en.wikipedia.org/wiki/Thermoelectric_effect" [Broken] can be used to convert heat directly to electricity but it is typically not very efficient (though it can be). This was used on the Voyager deep space probes for power. The heat generated by the decay of a plutonium pellet drove a thermoelectric junction to produce electricity.

Your question is very broad and "efficient" is a relative term. There is a maximum thermodynamic efficiency for converting heat to useful work based on the temperatures.

You can view a heat engine in analogue to say a water wheel. The heat flows in from higher temperature, the heat source and out to lower temperature, the heat sink, (like water falling from a higher altitude to a lower onel). The heat engine can convert some of that energy to useful work. The maximum possible efficiency is $1 - T_{cold}/T_{hot}$ (1 = 100%) where the temperatures are in absolute scale (say Kelvin or Rankin) i.e. degrees above absolute zero.

There's a good http://en.wikipedia.org/wiki/Heat_engine" [Broken] linking to many types of heat engines and discussing various aspects.

Last edited by a moderator: May 5, 2017