Are there any energy sources that produce a cold byproduct instead of a heat related one?

[slatr]

 

[CTho9305]

http://en.wikipedia.org/wiki/Endothermic_reaction says photosynthesis is endothermic, so I guess photosynthesis would count as a real energy source.

 

[BladeVenom]

There's the Seebeck effect, which is the opposite of the Peltier.

I think there was a news story recently about another method of converting heat directly to electricity. Can't remember anymore about it though.

 

[Mark R]

Depends what you mean by an 'energy source'.

You can power vehicles with liquid nitrogen - in this case, the exhaust is just freezing cold nitrogen gas. However, liquid nitrogen has to be produced using an external energy source.

 

[DrPizza]

Even with photosynthesis though, the energy "source" is the sun.

I think the OP needs to reword his question a bit. If he's thinking of a chemical reaction; there's always the reaction that occurs in cold packs (as well as a lot of other endothermic reactions) when you mix the two parts together and end up with a cold product. However, in that context, what would be meant by "energy source"?

 

[CTho9305]

Originally posted by: DrPizza
Even with photosynthesis though, the energy "source" is the sun.

Yes, but I was assuming things like solar power would count as an energy source from the OPs perspective.

I think the OP needs to reword his question a bit. If he's thinking of a chemical reaction; there's always the reaction that occurs in cold packs (as well as a lot of other endothermic reactions) when you mix the two parts together and end up with a cold product. However, in that context, what would be meant by "energy source"?

If we disallow solar energy and require that the energy comes from chemical potential energy... I don't know if that could exist. Anything that gets colder is taking in energy from the environment.

 

[rgwalt]

There is no such thing as an engine that will produce energy and cool its environment. There are endothermic chemical reactions, but all mechanical action produces some sort of heat byproduct. Remember that "cold" and "hot" are relative terms. Producing "cold" is simply drawing energy (as heat) away from one environment and either transferring it to another environment or transforming it into some other form of energy. Producing "cold" always requires additional energy to transfer heat away from an environment. This is why you must plug in your fridge or AC.

R

 

[BladeVenom]

Here's the article I mentioned. The chip converts heat to electricity. http://www.dailytech.com/article.aspx?newsid=5057

 

[BrownTown]

Umm, basic chemistry people, Gibbs free energy equation G = H - TS (more accurately delta G = delta H - T delta S). It is entirely possible for a chemical reaction to end up making products colder than the initial reactants. All you have to do is have an increase in entropy (like disolving ammonium nitrate in water, or allowing any liquid to turn to a gas). Of course, the entropy term is usually much smaller than the heat term at room temperature so normally reactions will produce heat, however if the reaction occurs in a very hot enviroment then the entropy term will dominate.

 

[JAGedlion]

actually, its a law of thermodynamics (can't remmebr which, one of carnot's I think) that there must be waste heat in a heat engine. (basically anthing like a combustion engine or refrigerator you know, stuff we use to power our generators on average, I dunno about things that deal with atomic reactions and only know the seebeck effect as that really cool thing that makes thermocouples work so I am not disqaulifying those possibilities.) While a heat engine with only a heat source and an output work does not violate the first law and therefore feels inherently possible in the gut, it is still not possible.