Wednesday, February 27, 2013

Electric Power From Any Heat Source - Really? Part 1

While working on another article, I stumbled across a few products that can convert heat directly into electricity. Hmmm....sounds like a great way to scavenge some watts back to our batteries when we are using our heaters. Especially the typical forced hot air RV furnace. Will this really work? let's take a closer look.

Likely, many of you have seen the "no moving parts" refrigerator/coolers that use "Peltier Effect" cooling modules. This uses power to cool one side of the module and heat the other. If you reverse the current flow, they will heat up instead of cool down. What we are doing, in essence, is heating up one side of the module and harvesting the electricity generated at the other, wire end. Most Thermoelectric generator modules use the "Seebeck Effect" a close cousin to Peltier.

Power Pot USB Charger
Not that much of this really matters. Simply put...heat goes in one side, electricity comes out the other. There are some existing products on the market now that take advantage of this effect. The first I found was a pot that you boil water in and it has a USB connector on it that will charge your cell phone and other small gadgets. It was called the "Power Pot." Yes, the name is funny, especially if you grew up in the 60's. It does work, but doesn't put out enough power to really make a dent in charging the RV house battery system. Right around 5 Watts at 5 Volts. The modules that make this happen will operate beginning at 250 degrees Fahrenheit to 600 degrees Fahrenheit depending on the module.
ThermoElectric Generator Module

Then there are the TEG (ThermoElectricGenerators) sourced from various companies. These are more in line with what I have in mind to test. They can be had in wattages and voltages ranging from a low of 1 Watt to a high of around 20 Watts. They'll also build custom TEGs and sell you separate modules to build it yourself. That's what I am looking into.

Atwood Style Exhaust Assembly
My concept is to wrap the inside furnace exhaust pipe with TEG modules then an insulating cover. As long as it doesn't affect the furnace or cause CO2 or Carbon Monoxide problems we may be able to significantly offset the furnace fan's draw. This can be a whopping 7.5 Amps or more! Wouldn't it be nice to not worry if your batteries will run your furnace overnight without going dead? If my experiments work, than we'll be able to do just that! Why waste heat dumped overboard? Recycle! Even if we cannot generate equal to or more than we use with the fan running, any power saved is a good thing.

Of course, it may not be COST effective. Stay tuned for Part 2 where I will be assembling various configurations and testing the concept. If it works, I'll have a good idea how much all this will cost. The modules I have been looking at are all around 40.00 dollars each. I believe between 2 and 6 modules will be enough. We'll see.

Be Seeing You...Down The Road,

Rich "The Wanderman"

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