TEG

http://www.tegpower.com/

Interesting read. I will do some more digging on it, and I will "do the math", but for now, I just thought I would post the concept.

Fish

The short answer:

  Code:

Temp 1  Temp 1  Temp 2  Temp 2           I       P      dT      dT      Degree C
  C       F       C       F     Volts   Amps    Power    C       F        mW/C
38     100.4   18      64.4     2.1    0.07     0.15    20      68       7.35
66     150.8   18      64.4     6.3    0.18     1.13    48     118      23.63
93     199.4   18      64.4     9.9    0.27     2.67    75     167      35.64
121     249.8   18      64.4    13.8    0.36     4.97   103     217      48.23
149     300.2   18      64.4    17.4    1.06    18.44   131     268     140.79
177     350.6   18      64.4    24      1.4     33.60   159     318     211.32
204     399.2   18      64.4    27.2    1.5     40.80   186     367     219.35
232     449.6   18      64.4    31.6    1.6     50.56   214     417     236.26


I have not gleaned enough about the physics of the phenomena to understand why the cost per watt is so high at low dT, but I expect I would find it is some combination of materials and construction. The "50W Product" offered for sale retails for $500, "wholesales" for $250, so one might assume cost of construction of the rather crude looking device is currently ~$125.

Assuming the cost of production could be reduced to ~$50 in a high volume setting, and assuming most "practical" solar applications would involve dT < 75C, and assuming power density for the assumed $50 unit could be increased to 5W @ 75C dT, we would have a fairly cheap and clean energy source for ~$10/W. But that is A LOT of assuming!

The physics appears to limit the efficiency to ~10%, so the only practical way to utilize such a device is in conjunction with naturally occurring thermoclines (rather rare) or in conjunction with "waste heat" or "exhaust", that is, this technology could never be considered for an economically viable primary energy source, but boosting efficiency of a larger system is potentially very attractive!

For a bit more detail on construction, applications and the technology in general:

http://www.electrochem.org/dl/interface ... p54-56.pdf

Prolly not for the average DIYer, sigh.

Fish

Hi Fish.
I believe that Voyager up to Cassini used radiothermal SNAPs and the Russkis even SNAPped some lighthouses up in the Arctic.
Still think that it would be more cost-effective for domestic PV panels to be dual-use leccy / water (or glycol)-heating jobbies, rather than PV on the front and Seebeck on the back. Get hot water too and of course in high insolation conditions the cooling would help the PV photons-to-volts conversion efficiency over that of a standard air-cooled thingy.

[Gotwind Ben]

I tend to agree this thermo electric is very much in it's infancy, efficiences are very poor at low temp differentials for power generation.
Not bad at higher temp differentials.

Until this technology is improved with possibly new material technology (I know Fujitsu are working in this area) the TEG modules are best suited, as Fish observed to "waste heat" or "exhaust" energy capture.

The underside of a vehicles exhaust system combined with the moving whilst travelling (cooling air) on a few TEG panels would most certainly provide at least an Amp @12v into a battery. I believe BMW are/have looked into this also.

The camping stove idea is pretty cool also on the TEG site.

How about thermo electric coasters - Top up your mobiles charge whilst you have a coffee! :?:
I'm in the realms of concepts again, probably be a wonderful marketing story for the likes of Starbucks, Costa coffee e.t.c

efficiencies are very poor at low temp differentials for power generation.

Actually the problem is that the available energy at low temp differentials is small, this is further exacerbated by the low conversion efficiency. As a comparison, a wind turbine with a 100sqft swept area that is 55% efficient in a 3m/s winds is still a relatively low power device (~95W) simply because there is not much energy in the wind (174W). If the same turbine is only 10% efficient in a 20m/s wind it is now a relatively high power device (4.6kW) even though there are 46kW of energy in the wind.

Anyway, the bottom line is that TEGs have narrow areas of practical deployment. Space, extreme environmental areas, and existing high heat loss systems being the best applications. I prolly should have read the fine print BEFORE I posted, LOL.

Fish