[LowKarmaAccount]

When I was in high school I looked into making a micro-power plant using the Seebeck effect for the Intel Science Talent Search. I thought about using liquid sodium as a heat sink, which is what some heliostats use. Solar power towers use the captured energy to power turbines, but this isn't very efficient, so I thought I would add thermoelectric generators to capture some of the energy that is lost as heat.

I ended up not doing this because the Seebeck effect isn't really a useful power-plant (in the broad sense of the word) when you have a small temperature gradient because it is really inefficient, although it is useful for thermometers and other low power items, and for some exotic things like Radioisotope Thermoelectric Generators, which is what powers Voyager and other long distance spacecraft. It becomes worth using when you have a large, consistent energy source, which is usually geothermal energy. But the small temperature difference between the human body and the flashlight and the low efficiency of thermocouples means that this project won't seriously compete with battery powered flashlights. However, it is a cool idea and could have some niche uses.

[pocketstar]

Yup, Seebeck is incredibly inefficient, as for RTG's in space I think they would rather use a Rankine cycle but that would be prohibitively too heavy to launch.

Good on your for using peltiers back in HS. In HS I made a sweet exoskeleton using peltiers for active cooling while outside in the summer heat.

[sigkill]

>Seebeck is incredibly inefficient

Yep, I was going to try to use that (peltier) in conjunction with a small array of solar panels to cool my car because summer afternoons can get incredibly hot - outside temperature reaches 45C, so I'm reasonably sure the car's interior would reach 55-60 easy. Alas! running some back of the envelope calculations (before jumping into the whole thing) I quickly discovered that I'm better off trying to find an efficient and tiny compressor, and large secondary battery to charge off the solar panels.

This problem still remains unsolved and no, remote start is not an option. I'm trying to craft something that is completely independent of the gas in the tank and preferably self sufficient.

[robomartin]

> Yep, I was going to try to use that (peltier) in conjunction with a small array of solar panels to cool my car because summer afternoons can get incredibly hot

A simple reflective car cover would do far more than all of that tech.

Smetimes it is really easy to over-engineer solutions to problems. I am reminded (and I am guilty) of this frequently.

[ISL]

This $15 thing will help with those first 15 C. Fancier ones exist.

http://www.sportsimportsltd.com/sopoaucofan.html

[sigkill]

I got that as a gift, and I have to unfortunately state that it's a negative. It does not help. Actually it helps even worse than cracking the windows down a little.

I do realize that the problem needs to be approached two fold - expelling hot air outside to reach ambient + cooling air that's being taken in some manner.

[Retric]

In full sun a car can easily have 1+kw of heat gain. Combating that with AC takes a lot of energy especially when you consider how long a car may be sitting out in the sun. But, cutting down on heat gain either by parking in the shade or having reflective shades can get you to close to air temperature fairly easily. However, combining would make things a lot easer.

So, if your willing to go all out and spend a few thousand on modding your car. Automatic shades for every window, a fair sized solar array on the roof and an independent AC system designed for continuous operation.

[Daniel_Newby]

Spacecraft use RTGs for reliability—they have no moving parts. Moving parts kill space missions.

[jlgreco]

Interestingly there have actually been a few nuclear reactors in space. Used primarily for radar satellites iirc that need power that RTGs and solar panels cannot provide.