diy solar

diy solar

Generating electricity out of the cold darkness of the night sky.

octal_ip said:
You'd probably receive a Nobel prize and would revolutionise energy generation across the world if you managed to outperform a normal generator with a solid-state device.
I have a peltier and have experimented with it. They're fun to play with and demonstrate some interesting concepts, but fail to impress when you try to do anything non-trivial with them.
The old steam powered turbine is still king for thermal-to-kinetic-to-electrical energy conversion. Your time might be best spent trying to find a small scale option? At least then the waste steam could still be used to heat your house before condensing back to water. You could even run a closed loop with the low temperatures outside assisting with the condensing step.
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Makes sense. Thanks for this. The steam powered turbine was my first thought but it seems quite inefficient in the scale of a small cabin and wood stove setup. You got any tips for me, where to start regarding small scale steam powered turbine system?
 
AJCrow said:
Makes sense. Thanks for this. The steam powered turbine was my first thought but it seems quite inefficient in the scale of a small cabin and wood stove setup. You got any tips for me, where to start regarding small scale steam powered turbine system?
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I'm not sure if there's anything commercially available at this scale, I'd hazard a guess that it would need to be DIY with a lot of careful engineering, and you'd still encounter the same challenges around economy vs a normal generator.
Stirling engines also come to mind, they're very simple heat engines but suffer the same level of inefficiency as peltiers at a small scale. It's not an easily solved problem.
 
octal_ip said:
I'm not sure if there's anything commercially available at this scale, I'd hazard a guess that it would need to be DIY with a lot of careful engineering, and you'd still encounter the same challenges around economy vs a normal generator.
Stirling engines also come to mind, they're very simple heat engines but suffer the same level of inefficiency as peltiers at a small scale. It's not an easily solved problem.
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Noisy diesel generator it is then.. :(
 
AJCrow said:
Yeah, this is my thought as well. But I would like to see someone try to perfect this. It's logical conclusion that whatever heat I turn into electricity I lose that heat and need to burn more fuel. But somehow my brain says that by using peltier elements I can utilize the cold outside as well and it would be net positive outcome. And this is a situation where it's freezing temperatures outside and there's nothing you can do about it, you need to burn fuel to heat your cabin and there's nothing you can do about it AND you need to charge your batteries somehow since you are using electricity in your cabin. So could this be more efficient than basic generator? At least it would be less noise.
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Russian company Termofor sells wood stoves that generate electricity but it’s small scale production (charging phone kind of thing)

Some discussion many months ago about improved efficiency with TEG, I think the concept was wrapping hot pipes.
 
I have played with the TEG modules a bit, too. I have had a couple on my woodstove on and off for a couple of years, but I end up sending them to heaven with over-temperature events. I have made as much as eight watts, though....
I have a genasun boost charge controller, and have charged my 500 Ah 48v LiFePO4 battery system (a little) with them just to be able to say I've done it. I think I got 4 watts for a day.


These guys have modules made for power generation (I've been using recycled cooler modules) which will be my next step if I continue. They also have some complete systems for sale, or at least sold them in the past.

https://thermoelectric-generator.com/teg-thermoelectric-power-generators-for-sale/

I intend to try to make 100 watts or so some day, but the problem is getting enough temperature differential.
 
Yes, may be impractical but...

newatlas.com

Thermoelectric device wraps around hot pipes to generate electricity

We've already heard about hoses that get wrapped around existing hot water pipes, using heat radiated from the pipe to heat water inside the hose. A new wrap-around device, however, uses that same pipe-heat to generate electricity.
newatlas.com newatlas.com

¨When applied to a hot gas flue pipe, the prototype is claimed to have exhibited the highest-ever reported output power and device power density from a single thermoelectric generator. In more detail, a 3-inch (76-mm)-squared version of the device utilized a 570 ºC (1,026 ºF) temperature difference to deliver a total power output of 56.6 watts.¨
 
TEC is practical for gas/oil wells, where unwanted gas is always flared off. Provides reliable power 24/7 for monitoring and communications equipment. Similar conditions to that hot pipe demonstration.

Demonstration units have been put on semi truck exhaust, eliminating load presented by alternator. Maybe not cost effective.

I use TEC all the time. It powers gas valve on my oven and water heater.
 
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