# Smoke stack generators?



## jawnn (Apr 28, 2010)

Some one told me that in northern europe they generate electricity with their heat stoves.

I want to stop wasting so much energy out the stack and use some of it for a generator.

Of course I haven't found any....so, HELP!


----------



## Ross (May 9, 2002)

Heat recovery units of any sort are banned in Ontario, and I suspect most places. chimney's need heat to work. Yes it is wasteful and yes simple technology could save billions of wasted energy and turn neg draft chimney's into pos draft vents..


----------



## Harry Chickpea (Dec 19, 2008)

The heat made the exhaust gasses less dense, so they rise up the stack. Take the heat away, and the stove becomes smokey. There is a balancing act to keeping the stack temp high enough to prevent this, but low enough not to waste excessive amounts of heat. The amount of electric power you can get out of stack heat is fairly minimal, enough to charge a few small batteries. Find an old cooler that plugs into a car's cigarette lighter and remove the peltier device. But a hot surface on one side and cold on the other and it will work in reverse and generate some electricity.


----------



## wy_white_wolf (Oct 14, 2004)

You could make a sterling engine that mounted on top of the stove. 

But I really think that would just make you burn more wood or whatever you use for heat.


----------



## jawnn (Apr 28, 2010)

so no one has heard of a smoke stack generator that works ....well all I have is a couple small batterys...and I did hear of one that is for truck exaust pipes.


----------



## Harry Chickpea (Dec 19, 2008)

Not sure how much access is available for free, but Make magazine has a website. On there is likely an online article describing the seeback generator someone made from a peltier device and a candle and heat sink. That would be a starting place for you.


----------



## jawnn (Apr 28, 2010)

the best way is steam... google steam electric generators


----------



## artificer (Feb 26, 2007)

jawnn said:


> so no one has heard of a smoke stack generator that works ....well all I have is a couple small batterys...and I did hear of one that is for truck exaust pipes.


Think about the differences between the two systems. A chimney in a properly done heating device should have gas temps of no more than 300-400 degrees F. Our masonry heater is down to around 215degF. The output of a fully stoked stove might be in the 75,000btu/hr range. Larger stove could be double that. At 75% efficient, you have 19,000btu/hr to possibly use.

If you look at a truck, and assume it get 15mpg, at 60mph thats 4 gallons/hr. Gas engines put about 40% out the exhaust, and diesels put around 33% out the exhaust. That means that if you use an average of 120,000 btu/gal for gas/diesel you're putting 192,000 or 160,000btu/hr out the exhaust. Its also at a higher temperature. There's a whole lot more "high quality" heat from the truck to use.

The last consideration between the two is that the chimney uses natural draft, while the engine is basically an air pump. You can put almost any heat collector on the engine exhaust, and as long as it isn't too restrictive, its fine.

I would love to have a heat powered battery charger, but I haven't figured it out yet. As close as I've come is to use heat pipes in the masonry heater to provide a controlled heat source to the peltier devices (Seebeck effect) and get a few amps that way. It would be enough to run a fan or small water pump, but not much else.

Michael


----------



## Jim-mi (May 15, 2002)

And think about all the energy the 'turbo charger' is using 'forcing' all those gasses out the Truck pipes.............
Sure you could put a spinning blade in there (the ex pipe) . .but it is still going to be a losing deal as to..........Energy in ver Energy out.

no free lunch here...


----------

