Ok, I think there is something that David and I myself are unclear on... Let's say you take IR radiation, so what is that?
A high frequency EM wave in the Teraherz range, if you have a nano antenna and diodes suited it could maybe be rectified directly to usable power, since this can be done with microwave energy I do not see any issues with doing it at IR at least in theory. Now I do know anything really about photovoltaic cells, but I imagine they do something like this, they rectify terahertz to DC. So is a temperature differential required to convert EM into DC electrical power? If you had a solar cell on the sun that somehow could survive such radiant temperatures, would it have no DC output? I guess it just seems (perhaps incorrectly?) that solar cells are somehow getting past the normal thermodynamic laws because they tap the EM radiation (which can be focused, polarized and interacted with electromagnetically) and not thermal energy directly. So are you saying that EM flux can not be tapped without a temperature differential? That if IR Emectromagnetic radiation were too homogeneous you could not rectify it??? John On Tue, Feb 5, 2013 at 9:05 AM, <mix...@bigpond.com> wrote: > In reply to Jones Beene's message of Tue, 29 Jan 2013 11:14:17 -0800: > Hi Jones, > [snip] > >In the end - if you want to find a practical and gainful > heat-to-electricity device close to ambient, then provide the virtual sink > well below ambient. That may be difficult, but Dirac permits it – and I > would never argue with PAM. > > ..wasn't it you who first mentioned mercury based semiconductors with a > very low > bandgap on this list? > > Quite apart from that however consider that the kinetic energy of molecules > tends to be distributed across all energy levels, so if energy can be > withdrawn > at *any* level, then that level will eventually be replenished by energy > from > the other levels (the sum of which will become depleted by the amount > withdrawn). This is essentially what happens with wind-chill. There is a > specific amount of energy required to break the hydrogen bonds between > water > molecules, and this is supplied by thermal energy of those molecules with > sufficient kinetic energy, with the temperature of the liquid dropping to > compensate for the lost energy, as the energy of the other molecules is > redistributed. > > The implication of this is that a semiconductor with any bandgap should > work, > though I would think that those with a smaller bandgap would probably work > faster as there is a larger population of low energy electrons than of high > energy electrons. > > Regards, > > Robin van Spaandonk > > http://rvanspaa.freehostia.com/project.html > >
