# Electricity Generating Heat Engines



## jebatty (Nov 2, 2011)

This may be a conference to watch. Many of us are interested in generating electricity in non-traditional ways, including use of wood to generate the heat. For those of us using wood for space heating and DHW, electricity generation would be very desirable add-on.

Heat Engines


----------



## Jags (Nov 2, 2011)

Jim - I have been a fan of this idea for quite a while.  I really wish some kind of "breakthrough" would happen.  Currently the most effective use of heat for electricity is still steam generation, that I am aware of.

Wouldn't it be cool to have a plate that could slap to the side of your stove and generate some wattage?


----------



## karl (Nov 3, 2011)

I think for the average guy, an internal combustion engine fed with wood gas would probably be the easiest.


----------



## billjustbill (Nov 9, 2011)

Electricity directly from heat...  Neat idea.  With more R&D for larger scale and cost effectiveness, it has some potential for wood burners like us....

http://www.tegpower.com/index.html


----------



## begreen (Nov 9, 2011)

Thanks for posting Jim. I've got to start playing with this. Time to move beyond the ecofan.


----------



## Hunderliggur (Nov 9, 2011)

The liquid system looks the best for boiler owners.  The derated cost is about $20/watt.  Solar PV is now available in the $1.50 to $2.00/watt range.  Worth keeping an eye on.  Since it is a Delta-T device, running on boiler output is probably more efficient than storage, but solar is a good heat source too.


----------



## begreen (Nov 9, 2011)

I'm curious about experimenting with this because the sun doesn't shine 24/7 here, or even at all many days in the winter. But the stove is running. 

Including shipping I get $5.8/w with this panel, is that incorrect?

http://www.tegpower.com/pro3.htm

and this unit claims 92w for $5.49, though I am not sure what the heat side power output is yet. 1 watt?
http://www.amazon.com/TEC1-12706-Thermoelectric-Peltier-Cooler-Volt/dp/B002UQQ3Q2/ref=pd_sim_e_1

I'd have to operate it bellow 100 Â°C but that should be possible with a good heatsink on our stove's rear heat shield or perhaps on a section of double-wall pipe?


----------



## Jags (Nov 9, 2011)

BeGreen said:
			
		

> I'm curious about experimenting with this because the sun doesn't shine 24/7 here, or even at all many days in the winter. But the stove is running.
> 
> Including shipping I get $5.8/w with this panel, is that incorrect?
> 
> http://www.tegpower.com/pro3.htm



15 V DC at 1 amp max.  So if you had 15 of these things running at the 260C temp (500F), you could run a friggen headlight from a car with them.  That is pretty impressive, but for some reason I am hesitant.  Something doesn't add up in my head and I don't know what it is.

Edit: I did notice that they will require external cooling from air or liquid.


----------



## Delta-T (Nov 9, 2011)

teg and stirling engines both suffer from the same drawback....must sustain the temp differential and they pretty much have to be disigned for a particular differential range. Both of these will work great in outer space.....I'm just having trouble figuring out how to run the extension cords.


----------



## begreen (Nov 9, 2011)

I'm thinking on a woodstove system, the differential is there between the stove top trivet or flue pipe and say a cooler inline with an OAK. Design a fluid transfer system and power a small, efficient dc pump to keep it cool.


----------



## Delta-T (Nov 9, 2011)

BeGreen said:
			
		

> I'm thinking on a woodstove system, the differential is there between the stove top trivet or flue pipe and say a cooler inline with an OAK. Design a fluid transfer system and power a small, efficient dc pump to keep it cool.



may not even need the pump....thermo syphon loop might work well enough. Using the OAK is a very sharp idear.


----------



## begreen (Nov 9, 2011)

Yeah, I would prefer a passive system. Will have to play with that one. I may do an initial test in the greenhouse. It has a much colder ambient temp.


----------



## Jags (Nov 9, 2011)

There it is!!  That is the part I was missing.  The energy consumption of maintaining the proper temp differential.  I think if I remember correctly that it takes almost as much energy to maintain the temp diff as the item produces, leaving a small gain.  Hmmmm... I like your cooling idea BG.  If a system could be done with very low power consumption, you may be able to hurdle that part of the equation.

Route the OAK to the t.e.g before entering the fire box???  Because the natural draft of the stove is free energy (so to speak).  I'm liking it.


----------



## mellow (Nov 9, 2011)

Thought this might be an idea to power my insert fan without having to run the power cord and also having it run during a power outage,  it would effectively shut off the fan when the temp cools down as a bonus.

Curious to see how this works for you guys.


----------



## begreen (Nov 9, 2011)

The same thought came to mind mellow. Tied to a battery and an inverter this would be handy for pellet stove owners. But it would only extend the battery useful period for a while. A basic 30watt system at 12 volts is supplying less than 3 amps or a generous trickle charge. My thought was for led power outage lighting and a jack for a small 12v TV or radio.


----------



## peakbagger (Nov 10, 2011)

There used to be a firm in Iceland that sold liquid cooled TEGs. I cant find a trace of them anymore. They set up a thermosyphon loop to the outdoors to cool the TEG. If I remember correctly even in Iceland they had a touhg time getting rated output due to inadequate cooling.


----------



## guy01 (Nov 10, 2011)

http://volodesigns-sterlingproject.blogspot.com/
This is a guy bloging about his quest to make a viable stirling(and asking for money to help)
maybe some of you can tell if he's on the right track
Guy


----------



## renewablejohn (Nov 14, 2011)

There is a wood pellet linear steam engine on the market but it is still quite expensive

http://www.buttonenergy.at/_lccms_/_00062/bison-Powerblock.htm?VER=110716135709&MID=64&LANG=eng

http://www.buttonenergy.at/_lccms_/_00060/Powerblock.htm?VER=110720165425&LANG=eng&MID=62


----------

