PROJECTS: SEEBECK GENERATOR

makezine.com/15/seebeck

In the Cooler

The Peltier and Seebeck effects exchange temperature differences and electricity. In a thermoelectric cooler, aka Peltier device, alternating slices of different semiconductor materials connect in a zigzag pattern between 2 plates. Heating one plate drives electrons away in one material while attracting them in the other. This induces an electric current in 1 direction — the Seebeck effect. Conversely, running a voltage across the junction draws heat toward one side while cooling the other — the Peltier effect.

The multiple junctions in the zigzag work in parallel, which multiplies the effects. Whether the device is used to convert a heat differential into voltage, or vice versa, it performs the conversion with no moving parts.

?\Xk Xggc`\[

?\Xk XYjfiY\[

?FK J@;<

:FC; J@;<

?FK ALE:K@FE

:FC; ALE:K@FE

:FC; ALE:K@FE ?FK ALE:K@FE

:LII<EK :LII<EK :LII<EK :LII<EK : FC; J@;< ?<8K J@EB ?FK J@;< ?<8K J@EB

?\Xk [`jj`gXk\[ ?\Xk [`jj`gXk\[ MFCK8>< ><E<I8K<; MFCK8>< 8GGC@<;

J<< 9<:B <==<:K G<CK@<I <==<:K

A junction between electron-donor and electron-accep-tor materials exhibits the Seebeck and Peltier effects.

Unfortunately, thermoelectric devices are typically only 1%–2% efficient, or 5% with the latest advances. This isn’t enough to make large-scale thermoelectric power generation (TEG) practical, although many researchers are trying to raise the efficiency. But thermoelectric generators are useful for other things; they can measure extreme differences in temperature, and are used in heating

124 Make: Volume 15

systems to power convection fans and pumps by using waste heat recovered from stovepipes and boilers.

The principle behind our Amazing Seebeck Generator is simple. We position our Peltier cell horizontally over our tin-can “furnace,” heat the underside with a candle or alcohol burner, and cool the topside with a heat sink and fan.

Illustration by Timmy Kucynda