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Would it theoretically be possible to create a nano-scale (or pico-scale?) electric generator that converts heat (atomic or molecular motion) into electric curr

Would it theoretically be possible to create a nano-scale (or pico-scale?) electric generator that converts heat (atomic or molecular motion) into electric current? It sounds too good to be true to have a refrigerator that generates energy, but I lack the education in quantum physics to understand why it would be unreasonable or impossible.

jayknight 3y ago
The Thermoelectric effect can produce electric current from a temperature difference (i.e. potential), but heat by itself can't do any work unless it has something colder to heat up. Refrigerators just do the inverse, they use an electrical potential to create a difference of temperature between the outside and inside of a box. https://en.m.wikipedia.org/wiki/Thermoelectric_effect https://en.m.wikipedia.org/wiki/Thermoelectric_effect
logtempo 3y ago
There are very small batteries that use the changes in its environments, but it use in general vibration, or light, or sugar (see https://en.wikipedia.org/wiki/Sugar_battery https://en.wikipedia.org/wiki/Sugar_battery). But the power is very small, used for very low power devices. One could think to use the sun cycle (become a little bit warm, then a little bit colder during the night), but at this point solar panel do the trick.
calamari4065 3y ago
To extract work, you need to move energy across a gradient. You can only generate electricity by moving heat from an area of high thermal energy to low thermal energy. The peltier or Seebeck effect does just this. By heating one side of the element and cooling the other, you get a small amount of electricity. It's impractical and very inefficient, though. Because you must cool one side, you have to have some sort of system to remove heat as quickly as you put it in. Active cooling with a fan requires too much energy, so you're left with passive cooling. As well, the amount of power you get goes down as the cold side gets hotter. There are plenty of good uses, though. Old gas water heaters actually used an electronic circuit to control the gas. A thermocouple is placed above the pilot light and creates enough energy to trigger the solenoid valve. Many types of temperature sensors work in the same way.

jayknight 3y ago

The Thermoelectric effect can produce electric current from a temperature difference (i.e. potential), but heat by itself can't do any work unless it has something colder to heat up. Refrigerators just do the inverse, they use an electrical potential to create a difference of temperature between the outside and inside of a box. https://en.m.wikipedia.org/wiki/Thermoelectric_effect https://en.m.wikipedia.org/wiki/Thermoelectric_effect

logtempo 3y ago

There are very small batteries that use the changes in its environments, but it use in general vibration, or light, or sugar (see https://en.wikipedia.org/wiki/Sugar_battery https://en.wikipedia.org/wiki/Sugar_battery). But the power is very small, used for very low power devices. One could think to use the sun cycle (become a little bit warm, then a little bit colder during the night), but at this point solar panel do the trick.

calamari4065 3y ago

To extract work, you need to move energy across a gradient. You can only generate electricity by moving heat from an area of high thermal energy to low thermal energy. The peltier or Seebeck effect does just this. By heating one side of the element and cooling the other, you get a small amount of electricity. It's impractical and very inefficient, though. Because you must cool one side, you have to have some sort of system to remove heat as quickly as you put it in. Active cooling with a fan requires too much energy, so you're left with passive cooling. As well, the amount of power you get goes down as the cold side gets hotter. There are plenty of good uses, though. Old gas water heaters actually used an electronic circuit to control the gas. A thermocouple is placed above the pilot light and creates enough energy to trigger the solenoid valve. Many types of temperature sensors work in the same way.