Thermoelectric generation

Discussion in 'Off Grid Living' started by oil pan 4, Oct 5, 2018.


  1. oil pan 4

    oil pan 4 Monkey+++

    I'm investigating the possibility of deriving power from solid fuels. Just burning something. There's boilers and steam engines, but steam engines require a lot of maintenance, super heated steam is preferred and boilers are dangerous. At the hight of the steam age in the late 1800s and early 1900s something like 50,000 people per year were killed in or because of boiler explosions. Besides all that I would be looking at a cost of a few thousand dollars for at most a few horsepower with no guarantee on how long it would last before it breaks or blows up.
    Also running a steam engine would be an active involved process, almost like a steam locomotive engineer and fireman.

    I already work with saturated steam coming from three 1,200hp boilers. So I'm well aware of how dangerous steam is.

    But using thermo electric generators for some degree of off grid or backup power is looking much more appealing.
    There are no moving parts aside from pumps for circulating hot and cold fluids. They work at much lower temperatures than steam engines.
    They have the potential to work with an air cooled cold side, but this would generate less power than a liquid cooled cold side, at least in theory.

    They are about as expensive as solar panels just to buy the thermoelectric cells.
    Then you have to come up with a way to heat and cool them. That's where all the money goes.

    So they end up costing at least several dollars per watt.

    To get the most power out of these units they should probably use a MPPT charge controller. That way the battery isn't over charged and the voltage can be handled efficiency across the wide voltage range these things develop.
    To get the most efficiency a variable speed hot water pump controlled by voltage would and an air cooled cold side seem like the way to go, in theory.
    My money would be on building and running them getting the most power out of them.

    Applications. I'm considering that thermoelectric generators could be used on their own or with a liquid cooled engine.
    Let's say I use a diesel engine to generate power to bulk charge batteries. You don't really need or want to run an engine to float charge batteries because they draw hardly any power during float compared to bulk charging. But while bulk charging the engine could be heating a hot water tank full of coolant, then that coolant could be used to heat a thermoelectric generator. A thermoelectric generation unit and mppt could float charge the batteries.

    Or build a fire and heat a tank of water and use that to generate some power.

    There is also a 3rd possibly. ThermoElectric from solar but I have already established these things are definitely going to produce power at a cost a lot higher than solar panels.
    The only thing that would be appealing is the ability to store hot water till night and create some power after the sun is down.
    Or produce power from excess solar heated water.
     
    UncleMorgan likes this.
  2. arleigh

    arleigh Goophy monkey

    After studying thermal electric a while my conclusion is , the best environment is a cold one normally .
    Being on a wood stove and putting the thermocouples on a stove pipe that is vertically run on the out side of the cold side of the house. the differential this system depends on needs significant heat and cold to produce efficiently.
    Not bad if you live normally in cold climates ,but then during the summer months one can run on solar .and wind year round.
     
    3cyl and UncleMorgan like this.
  3. BTPost

    BTPost Old Fart Snow Monkey Moderator

    I have a commercial TEG (Thermal Electric Generator) that generates 240 Watts and uses 1 USG of Propane a Day.... I will be installing it in my New Place’s Powerhouse this next Spring, and venting the Hot Air over to the Showerhouse/Sauna to use the excess Heat.... These are expensive to buy, and are NOT the most efficient way to make electricy, but for Remote Site Power they are simple and have No Moving Parts... The model I have has Remote Start and Shutdown capability, so I can set it up for Emergency Battery Charging, if all the other sources of charging fail, or are offline.
     
    Cruisin Sloth and UncleMorgan like this.
  4. DKR

    DKR Interesting ideas, interesting stories

    An external combustion generator. A TEG is one kind.

    A Rakiine cycle (ORC) genset an another. Unfortunately, these are far too large for a 'home' installation.
     
    UncleMorgan likes this.
  5. oil pan 4

    oil pan 4 Monkey+++

    These things are a plate, the hot and cold have to be on top of each other.
    Thermocouples only generate milivolts.
    The thermoelectric generator cells I was looking at can only take a max of 150C.
     
    UncleMorgan likes this.
  6. Ura-Ki

    Ura-Ki Grudge Monkey

    With today's boiler tech and electronic controls, I see no reason Steam cannot be used safely and reliably to power any need, and the HP doesn't need to be that high or steam pressure or temp needing to be so high as to be that dangerous!
    My little 40 horse Duplex is quite safe and provides plenty of power potential. it's more a novelty for me now, but it has the potential to provide plenty of useful work as I get back to playing around with it's capabilities! a 40 horse isn't a small engine, but it's not much larger then a Hit and Miss of only 4 horse power! As you know the power density is where Steam has every advantage, why not use it? Think how much WORK a 40 horse could preform per hour, I know I could drive a generator big enough to run my place at full "Hotel Load" and probably still have plenty of unused power left over, so it's totally capable, and the "fuel" can be any thing that burns or generates enough heat to steam up the boiler, Including Electricity!
     
    Motomom34, Dont and UncleMorgan like this.
  7. UncleMorgan

    UncleMorgan I eat vegetables. My friends are not vegetables.

    Simplicity is often an advantage, as is low cost fabrication.

    I would suggest you research "earth batteries". They were used in the 1800's to power telegraphs. Pretty simple rigs--just wires & stakes, basically.

    Just a thought, perhaps a little outside of the average box.
     
    Zimmy, Motomom34 and chelloveck like this.
  8. ghrit

    ghrit Bad company Administrator Founding Member

    If you have heat to "waste" look into Stirling engines.
     
    Cruisin Sloth and Ura-Ki like this.
  9. azrancher

    azrancher Monkey +++

    Wait... did I miss something, what is this "New Place"?

    Rancher
     
  10. ghrit

    ghrit Bad company Administrator Founding Member

    He's bought a place for when he retires ---- :lol:
     
  11. oil pan 4

    oil pan 4 Monkey+++

    I'm well aware of the power density of steam systems.
    At the hight of steam locomotive tech the largest one ever made was something like 70,000 horsepower.
    A typical diesel locomotive now is 5,000 to 7,000 horsepower, but they can put as many of them together as needed.
     
  12. BTPost

    BTPost Old Fart Snow Monkey Moderator

    We just concluded a Land Exchange that had us sell our Beach Cabin, and lot, plus our 5 acre UpLand Lot for a Total of $200K, and then bought a 4.5 acre Twin Cabin, Powerhouse, Showerhouse/Sauna, Twin Tool Sheds, Garage, Kubota Tractor w FrontLoader & Backhoe, and SawMill, three 4Wheelers, 14’ Lund Skiff w35hp Outboard/Trailer, and the other half of my Suzuki Samurai... for the same $200K... It was a straight across deal, and we got a “ Turn Key Operation... The place is up on the Mtn. just 1.8 miles south of the Cannery, with great road access from there... AlaskaChick dreamed up this scheme last winter, and worked on getting all the parties, together to make it happen, during the summer, and the final negotiations were concluded in mid September, with the Closing an both deals on October 2... So now We have a place we own, that can store all the stuff we have collected for 50 years, and room for family and friends, that want to come visit. It is only by prudent financial planning and wise spending, that we were able to pull this deal off, and not use any of our Savings or current Income to conclude the deal...

    The previous Owners are very good friens who spend there summers, here, but are now in their 80’s and have are nice winter place in Aridzonia... Our deal with them is they can continue to come north, each summer and live in the lower Cabin, for as long as I have the Cannery Job, or their health allows.. We have partnered with them on different things over the years, and this way they can continue to do what they love, and use the money to Go Debt Free, plus have a nice NestEgg to leave their Grandson... and we get their firsthand experience, of running the place and learning the operations...

    WE are NOT Homeless, any longer, as we live in Cannery Housing now, but now have a REAL Home, that is OURS... I never thought she could make this deal happen, but she did, and we kept it completely OPSec until the Deal was concluded, and Deed Recorded... That is the BIG NEWS from Bush Alaska....
     
    azrancher, Alf60, arleigh and 2 others like this.
  13. Cruisin Sloth

    Cruisin Sloth Special & Slow

    Very Kewl Mr B
     
  14. arleigh

    arleigh Goophy monkey

    I wish you the best ,
    I don't know why I'm jealous . Ya I do
    You got a great wife.
     
  15. azrancher

    azrancher Monkey +++

    WOW, I'm impressed, and you got the 4-wheelers too!

    Where in Aridzona?
    Rancher
     
  16. oil pan 4

    oil pan 4 Monkey+++

  17. BenP

    BenP Monkey+ Site Supporter+

    That is what has been powering those voyager satellites for the past 40 years, they make about 400 watts and they use plutonium for a heat source.
     
  18. oil pan 4

    oil pan 4 Monkey+++

    Yeah plutonium 238 is pretty cool.
     
  19. arleigh

    arleigh Goophy monkey

    I have a little TEG fan on my wood stove.
    It does not put out enough air to put out a match but it does circulate the air
     
  20. BTPost

    BTPost Old Fart Snow Monkey Moderator

    We have one of those "ECOFans on our Oil Stove in the kitchen... We also have an LED Lamp made by the same folks that uses a Tea Candle to provide Heat to the TEG Pile, and it has a series of White LEDs that can be used as a Reading Lamp after the Genset goes off at 10Pm... very cool item...
     
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