 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Solar : Electricity From Heat
| Author | Message | ||||
MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Has anyone here old or new tried (or heard of being tried) making usable amounts of electricity directly from collected (solar) heat? This would likely involve coming up with some sort of 'ginormous' thermocouple device. I've decided to put on the 'ol thinking cap to see if I can come up with something. Maybe a system using several gas-charged pistons in sealed cylinders that react to the temperature difference between sunlight and shade. The possibilities are endless. The trick will be to make enough usable juice. Just think how cool it would be if you could recover waste heat and turn it directly into usable electricity without having to first manufacture steam or swap gulps of air in a Sterling-Cycle engine! Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
||||
Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566 |
MacGyver; quote; Has anyone here old or new tried (or heard of being tried) making usable amounts of electricity directly from collected (solar) heat? End Quote. A link for you Mac TEG's Time has proven that I am blind to the Obvious, some of the above may be True? |
||||
GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
The thermo electric generators are commonly used in the small cooler/warmer eskies. These unit rely on having the heat, and cool places being brought close together through heat conduction channels. There arer specific temperature limitations on the electronic junction devices. cannot remember specifics, but manufacturers will have them. These are not efficient units, but can give power when not many other options are available. Gordon. become more energy aware |
||||
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Hi Mac, Yes i looked into it some time back and found it was not worth the effort of attempting a project out of it. Also found that i think it was the swedish goverment conducted a study on recovering heat from home heating stoves into electricity but it was not a viable prospect. By memory there needs to be a 80C difference across the cell to produce useable power. My thought was to use a parabolic dish to heat the cell. The more i looked into it the lesser the idea become. As Gordon said not very efficient units and not very reliable either. My conclusion was you be better off boiling the kettle and making a cup of tea and putting your feet up. The energy you will save is more than you will make. Pete. Sometimes it just works |
||||
| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
My assumption was that most posts would simply refer me back to what I say in my 4m signature line, "Nothing difficult is ever easy." but I'm particularly happy for the "TEG" link from Greenbelt; thanks. I'm the eternal optimist and for some strange reason always believe there is a way to do stuff that seems otherwise impossible. Thanks again for that terrific link! . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
||||
| Barry T Coles Senior Member Joined: 30/07/2009 Location: AustraliaPosts: 109 |
I have a TEG at home that was used about 30 years ago as a low voltage power source for the company's remote two way radio re-transmitters for when there was constant cloud cover,usually when cyclonic conditions created extended cloudy periods. Unfortunately I am in Perth until the end of April otherwise I would post some photo's, the basics of the operation is that heat by way of LP Gas flame is passed through dissimilar metal coils,the result is 12 volt DC but only low Amps (about 3 Amp)the one I have I believe was made in the UK & is called an Isotope, I intend to experiment with it trying to use methane gas generated from enclosed composter's. When I get back home if I remember I will get some pics & post on this thread. Cheers Barry I need to learn from the mistakes of others. I dont have the time to make them all myself. |
||||
| Robb Senior Member Joined: 01/08/2007 Location: AustraliaPosts: 221 |
I heard of microwave comms links being powered this way back in the 1970s. They would do a gas cylinder swap by chopper every month. The thermocouples in gas heaters etc produce enough juice to hold a solenoid valve open so they could be a starting point and available at the local rubbish tip  I expect they are ultra low voltage though. |
||||
| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Robb I'm a plumber and I'm aware of the valve-holding property of 24 mv thermocouples. Part of the reason this works is that the two mating surfaces in the pilot valve (inside a gas safety valve) are highly polished. They are so smooth, the almost "cohere". The added holding power of the tiny electromagnet is "just" over the top and holds it open while there is a standing flame impinging on the end of the thermocouple or thermopile. This is all fine and dandy, but I'm looking for more along the lines of that "TEG" gizmo. I'm hoping to find or develop something that can compete with PV or at least something along those lines. Thanks for your post. Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
||||
| Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566 |
MacGyver; I found a web page with a voltage table for thermocouples, It really didn't light up my life. One thing showed a little promise but only for desperate times. Ampere flow is very respectable. I drew this up as a memo to my self, working with something for a while helps me remember a few details about what I've been checking out. So I will remember no volts, Good Amps. It would be interesting to put a couple thousand together and cook um in the california Sun. May need some concentrating Mirrors to get 300 deg. The hotter it is the better it works but again, Not by much. 
Time has proven that I am blind to the Obvious, some of the above may be True? |
||||
| jamiec Newbie  Joined: 21/07/2008 Location: AustraliaPosts: 3 |
Hi have a look at this it is interesting http://www.youtube.com/watch?v=VaRMRDO7Q88&feature=channel |
||||
KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
Yeikes, $1600 for 48V for 100W, I'll have to move to the third world where these are intended to be cheap. I reckon you could mount the little radiators all over the house, run a ring main and have these things all over the woodheater! bit too dear, I'll put the $1600 towards the AXFX.... which when its cold and windy outside and the solar isnt doing anything.....will be pumping in 1000's  Luck favours the well prepared |
||||
| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Greenbelt I actually did something on the order of your little picture about 35 years ago. i used copper and iron and it did work, but was grossly inefficient. As a plumber, I have a "special" meter for checking 24 milivolt thermocouples in water heaters and space heaters and using it to check the output of my home-made contraption, the thing didn't work as well as merely tying together about 1/10th as many "commercially manufactured" thermocouples! The commercial ones are made of actual semi-conductor materials (I should know, but don't!). I like the idea of the TEGs and will likely lean in that direction as I further investigate this phenomenon. I have a friend who owns an electronics shop and he has a "bone pile" with one of everything and two of everything else. I"m going to take a swim through it (the pile) and see if I can find some semi-conductor parts like those shown on the TEG Power.com site. Thanks for your efforts. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
||||
| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
jamiec You're right about one thing, it is very interesting. I'm not sure what "it" is and all it seems to do is make noise and glow, so I'm at a bit of a loss. My suspicion is that on the other side of the lab, the side they don't show, some guy in a white lab coat, with Coke-bottle-bottom glasses is busily preparing the Frankenstein monster for his second shot at life! I have to admit; I didn't watch the video through to the end. All the thing did was click and glow for the first half of the show, so I got bored and hit the back button. Maybe I'll go back for a second look, but I'll have to stock up on milk and cookies for that!  Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
||||
| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Crew My, how time flies. I'm picking up this thread again, because, as promised away back in the day (2009) I said I was donning my thinking cap and I have done just that. I've come up with two very inexpensive materials, which, when heated at one end and cooled at the other (using ambient air) create SIGNIFICANT voltage and current. My son, the PhD Aeronautical Engineer, is interested as well, which is unusual, because most (read that: nearly everything) I come up with, he could care less about, but this idea, he's said, has merit. I'm in the process of building a test panel and we'll go from there. The goal is to manufacture a similar-sized solar-thermoelectric panel, approximately the same size as a working silicon solar electric panel, but at a fraction of the cost. If I can do this, it will mean an end to the worry of heat degradation as a traditional solar-electric panel warms in the sunlight and starts losing efficiency. This new thing thrives on heat! Here's the catch (always a catch): As previously stated, the trick will be to make one small enough and efficient enough to rival the output of a similar-sized solar panel. If I can pull that off, we'll really have something. More as it happens. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
||||
| davef Guru Joined: 14/05/2006 Location: New ZealandPosts: 499 |
More than 5 to 8% efficient? You have done a patent search on the materials you propose to use? Good luck! Dave |
||||
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
There was experiments being conducted here in Australia a number of years ago using brine ponds to collect solar energy. The heat was used by running a refrigerant gas through the pond to boil it and drive a gas turbine. I don't remember all the details but the brine stayed hotter near the bottom of the pond for some reason and therefore there was not a lot heat lost to the atmosphere. Sounds like something that someone with a name like MacGyver could make. There are only 10 types of people in the world: those who understand binary, and those who don't. |
||||
| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
To me its all been done before, and if you search "Peltier" cells you will find exactly what you are talking about, then search Ebay and you can buy as many as you want cheap. I think there was a study done in Sweden or close by where the goverment looked at recovering energy from home heating systems, but i think it was a failure. It mostly comes down to a big enough thermal difference from one side of the cell to the other, the greater the difference the greater the current produced, so to clad your heater with cells would also cool your room on the reverse side, so not practicle. This was all discussed on the forum some years back, but i dont remember the actual thread now. Pete. Sometimes it just works |
||||
powerednut Senior Member Joined: 09/12/2009 Location: AustraliaPosts: 221 |
I've got a friend who is working on a peltier based generator add on for a wood stove. He is finding the peltiers are remarkably fragile, and die easily if you get them too hot. I believe the russians used to make use of thermopile (thermocouple) generators in siberia. The cold made them much more efficient. I think the set up I saw a photo of was a 3/4 circle thing that was supposed to be set up around the camp fire. Fins on the back would get snow heaped on them, to improve the efficiency. Total output voltage was somewhere around 2-3V, but that was a lot of thermocouples. They were used to charge NiFe batteries I think. Given your small wind turbines and compressors I would have thought you would prefer to go with a stirling engine mac. |
||||
| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
powerednut et al This little project takes me way out of my comfort zone, but I'm always up for a challenge. As for a patent search, that'll never happen, by me at least. I'm not in this for money; I'm in it for the fun of it all only. Sterling engines are very fickle. I've built several and they do work, but are fraught with problems, mostly lubrication problems; not for me. The main thrust here is to build something SIMPLE that anyone can do. The materials I'm using are common-place stuff, most likely in everyone's back shed. So far, I've used a small torch to "test" with and the temperature difference is mammoth compared to that of using sunlight and ambient air temperature to cool the "cold" end of the thermopile. I figure using a torch gives me instant readable results and as long as I use it for ALL my testing, it will make getting to goal that much easier. Like I said before, the trick will be to make this thing robust enough to replace silicon solar panels and not be as big as a football field. I'll keep you in the loop. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
||||
 Print this page |
