I have a friend who built a completely passive, zero electricity required air conditioning system for his home. The gist of it is this. He dropped steel pipe five feet into the ground running through his backyard. One end stuck up above ground, the other end connected directly into his basement. He then went through and made sure that his house could be as completely air tight sealed as possible with the exception of a vent out of the top of his roof. From there it is basic physics. Hot air flowed up and out of the roof vent, the resulting pressure change drew air in from the pipe that was running through the ground. Once you hit three feet below ground the temperature is a relatively constant 56ish degrees F. So all the air moving into the house was cool. Hello the beauty of science at work! Zero electricity required and his house maintained a relatively constant 70 degrees during the summer no matter how warm it was outside.
First of all, I very much want to set up a system like that in my own house, but foresee some issues given my location. He was in the desert of Arizona (dry air), I am in Virginia, and it is VERY humid during the summer. I still need to figure out how to make it work and not allow water from the air to condense and lead to mold problems.
For now, I want to put the same principals to work to create a passive electrical generator. With any liquid or gas, the higher temperature liquid or gas will rise to the top of a given system due to the expansion and lower mass to volume ratio. I want to develop a closed loop system, where water in aluminum piping will heat, by virtue of it's lower mass to volume ratio, move to a higher point, where it can cool, and cycle back into the heating area. This should create a current that could be tapped to generate electricity. Here is my rough schematic:
The gist of it is this. The entire closed loop system is filled with water. The area marked
1. or
Heating Assembly is a series of blackened aluminum pipe that folds back on itself creating a rectangular area that is placed in a full sun area. The line out
2. of the Heating Assembly will carry heated, and less dense, water to a higher elevation. The
Cooling Assembly or
3. can be a coil of pipe that is in a shaded area that will naturally be cooler than the water that was in the sun (I have a perfect area for this that is in an enclosure under my second story deck). That water will then be allowed to drop down into
4. the
Electricity Generator(slightly incorrectly labeled in the diagram). The Electricity Generator will be a converted water pump that utilizes a permanent magnet motor to generate electricity from the current that will develop in the loop. The water will then go into either piping or a tank, the
Feed (also shaded) will then feed back into the Heating Assembly. I am not sure if I will bury the Feed in order to allow it to cool the water faster or if I need to leave it level with the Heating Assembly so as not to try to fight gravity. The pressure changes and current that develops should cause it to draw water either way but I am still hazy on if the system will lose power to gravity if it has to draw the water up from under ground. There is only so much practical application my brain can calculate at once.
Thoughts? Is this practical? Could it be accomplished? I know some one is going to say that the amount of electricity produced in a system like this will not be tremendous, but that is not my concern at the moment. I am curious it my concept is sound first.
I had considered that possibility but did not think it would be too likely considering we are only heating with sunlight and not a more robust source of heat. That being said, I have an idea how to minimize the possible issue with pressure. Even though it is a closed system, I will require a few access points to the system. Probably one at the highest point (filling) and one at the lowest point (draining). If I left the access point at the highest point open until the middle of a hot day, the system should be at peak pressure and if I sealed it at that point the pressure would only be able to decrease, but never pass that level.
If, it were not actually sealed, but instead towards the top there was a holding tank with room left for water levels to rise an fall based on changes in pressure that would alleviate the question of pressure building. It also should not interfere with the current I am trying to establish as the density changes in the water will still work the same way in either an open or closed system. As long as we give the heated water a way to move to a higher position, and ensure that once at that higher position the water is able to cool and move to a lower position that will then feed the heating assembly shouldn't the current develop?
