New form of mechanical advantage: Off season research potential

[Kevin Sevcik]

Originally Posted by 4057programmer

Well for places within the arctic circles should be able to accomplish this easily. For those in more tropical climates I recommend looking into Einstein's only patent for solar refrigeration. The link is Wikipedia but it does a good job explaining it.
http://en.wikipedia.org/wiki/Einstein_refrigerator

The other place this would be of great use is space, the moon, and any other rock out there without an atmosphere.

You can certainly use this to generate a lot of hydraulic pressure without a hydraulic pump. So it'd be extremely useful in, say, a MacGuyver episode. In fact it probably has already been used in one.

You're never going to use this for practical power generation, however. The thermodynamics there are pretty clear. As I see it, you have a few problems with this:
1. It's inefficient. The Carnot Cycle is provably the most efficient way of turning heat into work. Every other method of turning heat into work is guaranteed to be less efficient. The important equation is:

Eff. = Work /  HeatIn = 1 - (TempCold/TempHot)

Those temperatures are absolute, so Kelvin or Rankine. In the above video, you're talking about something like 273K (0C) and, at most, 373K. So the best you can do is 27% efficiency. Which isn't bad, but you have to start with boiling water. On the plus side, the cycle probably gets pretty close to Carnot Efficiency, since the heat transfer is so slow and you'd get such little power out of it.
2. You won't get much power out of this. You're not going to get ice to form quickly or melt quickly.
3. You still have to melt the ice afterwards if you want to do anything else. This is not free energy. Space and/or the Arctic can be a pretty big heat sink, but you still have to make heat to have liquid water to start with. If you're going to all that trouble to melt the water, why not melt it a little more into steam and have yourself a steam engine or stirling engine with your limitless cold as a heatsink? Then you can work higher temperature differentials and likely get better efficiency.

This isn't to say you can't do clever things with ice to make power generation more efficient. In hot climates, large buildings often use off-peak ice storage to make air conditioning cheaper. The system will create ice at night when electricity is cheaper and often cleaner*. Then during the day, the ice is used as a very effective heat sink for the air conditioning system.

*Cleaner because less coal-fired, gas-fired, etc. plants that have to be ramped up to cover peak electrical loads.

[RunawayEngineer]

Originally Posted by Kevin Sevcik

You can certainly use this to generate a lot of hydraulic pressure without a hydraulic pump. So it'd be extremely useful in, say, a MacGuyver episode. In fact it probably has already been used in one.

I believe in the first season, he uses the principle to escape from a locked freezer. He melted ice with the lightbulb and guided the trickling stream into the lock. When the water refroze, the pressure of expansion broke the lock.
Still waiting on the Mythbusters to test it.

This phenomenon could be helpful in certain circumstances. There are more obscure and inefficient machines that have found their niche.