Misleading education:

"A necessary component of a heat engine...is that two temperatures are involved" http://physics.bu.edu/~duffy/py105/Heatengines.html

Actually one-temperature (isothermal) heat engines are commonplace - e.g. pH-sensitive polymers can cyclically do work as they swell or contract. No "two temperatures" involved:

https://pbs.twimg.com/media/Dqasx5_WoAAV6XY.jpg

By adding and removing hydrogen ions (H+) one can cyclically extract work from pH-sensitive polymers:

https://pbs.twimg.com/media/DmP8OHKXcAAerSI.jpg

(This is Fig. 4 on p. 15 he https://www.ncbi.nlm.nih.gov/pmc/art...00645-0017.pdf)

Adding and removing H+, per se, consumes no work if done QUASISTATICALLY. This means that the work lost e.g. in adding is compensated by the work gained in removing, and the net work involved is zero.

In his famous lectures

http://www.feynmanlectures.caltech.edu/I_44.html

Feynman discusses the non-isothermal analog which, at least apparently, doesn't violate the second law:

http://readingpenrose.files.wordpres...and-engine.gif

In the isothermal case the two temperatures are replaced by "adding and removing H+" which, if performed QUASISTATICALLY, consumes no work. So the system just lifts weights for us, at the expense of ambient heat and in violation of the second law of thermodynamics.

Heat engines working under isothermal conditions (no "two temperatures") and able to violate the second law of thermodynamics are commonplace. They are too slow and impuissant to be of any technological importance, and this is one of the reasons why scientists pay them no attention. Yet there seems to be an exception: When water is placed in an electric field, the non-conservative force (pressure) that emerges in the bulk triggers vigorous (by no means impuissant) motion apparently able to convert ambient heat into work quite efficiently:

https://www.youtube.com/watch?v=17UD1goTFhQ

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