Low maintenance low cost and ambient lightning summer project. - Page 1
Forum section: electronics / projects

author: atos
author_rank: Contributor
timestamp: April 14, 2015, 03:39:02 am
content: I've had this idea for a while now I came to think of in regard to the subject, just want to get it out of my head. Say that you take a ceramic heat plate rated at a few watts and couple it together with two slightly larger TEC:s in a vacuum, then run the TECs (once the element reach at a specified temperature) in a feedback circuit connected to the heat plate and use the residual heat from the element as it is turned off at a defined temperature to generate power to further drop the temperature or turn the element back on.Provided energy is added to start the reaction from say a winding crank generator, how long could it keep going on its own? I know there is some variable I haven't accounted for, otherwise it would have been discovered since long. There should obviously be some thermal radiation, hence the vacuum to counter that which is also another addition of energy in a sort of sense. But the residual heat is the thing I'm curious about since it would basically act like an inefficient accumulator coupled with the TECs.I plan on making prototypes during the summer. But since I'm not that well conversant in the mostly abstract intangible parts of physics and thermodynamics, I was hoping someone had some valuable input. Cause I know I have forgotten something, and it's not to "smile and dance and sing".But to the topic of the subject, the original plan, which is to evaluate how useful a solar powered recirculating water system connected to series of water blocks with TECs could be in cutting my electricity bill. It's basically an untapped source of energy around here where temperature changes a lot throughout the year and most households in the area have more or less free district heating. I figured it's a workable concept all year. If you don't have district heating, you could just use outside temperature and swap the polarity of the TECs once WINTER IS COMING!5:30am, I'm qualified to have a slightly below normal silly mood in terms of humor and grammar.

author: paulie
author_rank: Frequent Contributor
timestamp: April 14, 2015, 10:22:20 am
content: Quote from: atos on April 14, 2015, 03:39:02 amIt sounds like you may have discovered the first true method for free energy. Aside from solving all the worlds economic problems I am fascinated by the prospect of generating "ambient lightning" bolts with no power input. Please keep us updated.

author: atos
author_rank: Contributor
timestamp: April 14, 2015, 02:15:21 pm
content: Quote from: paulie on April 14, 2015, 10:22:20 amHah it "struck me" after reading it. Lets hope it has as huge potential as it seem at first glance.

author: ajb
author_rank: Super Contributor
timestamp: April 14, 2015, 06:05:30 pm
content: According to wikipedia, thermoelectric generators typically have an efficiency of 5-8%, so that doesn't bode well for your hotplate-powered-TEG-powered-hotplate perpetual energy idea.Remember that in order for a TEG to generate electricity, heat has to flow through it. Even if your district heat (hot water?) is free, you're still talking about building a system that will consume an immense amount of energy from your district heat, and 92+% of that energy will wind up as residual heat that has to be removed from the cold side of the TEG. What are you going to do with all that heat?

author: atos
author_rank: Contributor
timestamp: April 14, 2015, 08:50:41 pm
content: Yeah I realize the efficiency is low. Keep in mind that I brought up two different ideas, and I did not intentionally connect the two, sorry if I was unclear, as stated on the bottom I didn't sleep that night, only slept two hours in the morning and still up and kicking.The heat plate has no place in the latter idea, that was simply something that struck me by coincidence as I pondered the latter one, I guess I should have swapped the order I wrote em. But that idea is more about finding out how much residual thermal radiation escapes the TECs in a vacuum.But in regards to the latter (which should have been the first),the only thing that consumes electrical energy in the system is a circulation pump, and even this is optional if you use a hydram which is powered by water pressure alone. Since I live in an apartment way above ground level I don't have that option. However I do have south facing windows and a balcony so both solar and wind power is possible, but also solar panels. The latter fits well into the concept if an intended user lack access to district heating. So that point somewhat moot if you add a battery to keep the pump going. Then again one could also use a small valve and use the pressure from the tap to have the system running, and that pressure could in turn be used to drive a small hydroelectric generator along the way since those don't diminish the pressure much in that scenario.Using water as a medium the actual temperature of the TEC never go above 100C (unless we are talking about really freaky conditions like +12000K and plasma, which is highly unlikely to occur) in the intended environment, so that point is moot. :pSince water has a pretty decent amount of energy storage I think it would be fairly energy efficient as well. This system I'm talking about is about as large as the attached picture which is about 40x40mm, add a Cree LED or something to other side and you have cooling for it as well and you can reuse the residual heat to keep the water warmer than ambient temperature. Even if the water is room temperature then the option of adding a slightly larger water block to the back of a refrigerator for example could solve it to active temperature difference needed to generate power. Heat is not an issue for the system to work, it's a necessity, and it's regulated by the innate properties of water. At a higher attitude it would probably work even better.I might have misunderstood you, cause it appears to me as you are mixing the two separate ideas I brought up. Granted I didn't separate em well enough, that's my bad. Hope I made things somewhat clearer.

author: ajb
author_rank: Super Contributor
timestamp: April 14, 2015, 09:59:17 pm
content: So your idea is to put solar water heaters in the windows, and use the heat captured by them to run a TEG? I suggest you look up the solar insolation (W/m^2) for your part of the world, and multiply by the area of your windows. That gives the total amount of power available to be captured. Multiply that by 0.05 or 0.08, and you'll have the total amount of power you can capture with a TEG assuming your solar heaters can capture all of the available energy. If that number isn't low enough to discourage you, then you can start figuring out how efficient you can make the collectors and add that number into the formula. For the sake of completeness, you should also deduct the additional power you'll need for lighting during the day, since your windows are now covered by solar collectors, unless you like to live in a lightless cave. You should also account for the fact that 92-95% of the energy that makes it to the TEG comes out as heat at its cold side, so you'll need to account for the extra cooling you'll need for your home (even if you don't mind the increased the temperature, reducing the temperature delta across the TEG will reduce the amount of power it can produce). If you dump that heat into your refrigerator via a cold-side water loop, then you also need to account for the energy used by the refrigerator to move that heat from inside the fridge to the outside.QuoteThe rate at which an object loses heat via radiation depends on the surface area of the object and the emissivity of that surface.

author: atos
author_rank: Contributor
timestamp: April 15, 2015, 12:13:29 am
content: No, what I wrote was that it is one out of many possible ways to generate a temperature difference.Good input, thanks, made some rough estimations. Still seems viable. Even if my price calculations where more than a little bit off. It's pretty low investment cost compared to other renewable energy sources. But in the long run TEGs should age pretty well.I but as I said, I have no delusions about taking out much power.