Thermoelectric systems produce electrical energy out of a heat-source.

Video with a lot of basic experiments. Main conclusion: Stirling are way more efficient (they can rise up to 40% instead of 1% for Peltier modules.)

Peltier Elements

• General article
• Design #1
• http://www.magistrala.cz/freeenergy/search/homemade-peltier-element

Thermoelectric generators

• Made of aluminium and a pencil
• http://www.scraptopower.co.uk/thermoelectric/Thermoelectric-lamp-seebeck-generator
• tPOD1 (commercial
• youtu.be/dMD4GlzLPzw

From Wikipedia:

• Used to be made of bimetallic junctions.
• Are now made of highly doped semiconductors, from bismuth telluride, or lead telluride, or calcium manganese oxide.
• Electromechanical systems including turbines, such as Stirling engines, are more efficient.