The article is hard to follow (so I haven't), but I think it is a misinterpretation of changes in efficiencies of electochemical conversion (theoretically extremely efficient) versus temperature, rather than anything to do with conversion of heat to mechanical (or electrical) energy.

Fyz

The flaw in the argument for a second law violation comes from neglecting the fact that the electrochemical cycle relies on a temperature difference. The description clearly points out that the two key steps in the process occur at 903 deg C and 688 deg C. A simple thermocouple could already extract electric current fom such a large temperatre difference. Perhaps the process achieves unusually high energy efficiency, but that is a far cry from overturning the 2nd law.

Over the years there has been more than one example of second law violation, some being quite obvious. One which fits into that category is the ball which bounces ever higher. Where does the energy come from? The ball becomes colder with each bounce.

Bernie Katz

I assume you are either being provocative, or that you meant "apparent second law violation"?

Fyz

As you like

But where is the error?

How many of these do I need for my refrigerator so I can pull the plug?

Efficiency of electrochemical cells is 90%.

O.K. Lets calculate with 80%!

Carnot efficiency is 0.18 from 1176 to 961 Kelvin.

The cell produces 80% electric energy and 20% thermal energy.

We need only 4 percent electric energy for refrigerator.

Are you simply saying that avoiding the thermal stage between chemical and electrical energy is a good idea - if so, I agree.

However, the way you write the statement, it is easiest read as implying that this is counter to thermodynamics. In case you mean this (or it is read and accepted as such) I would make the following comment: conversion between ordered forms of energy can theoretically be 100% efficient. The common example of very high efficiency around room temperature is between mechanical energy and electrical energy (and vice versa), and no-one regards this as odd. Chemical energy is another form of ordered energy storage, so there is no difference in principle, and we are quite accustomed to this conversion taking place with high efficiencies in batteries. However, any time that someone does this work using fuels that are usually burned, there seems to be a flurry of comments implying that the second law is being broken, and we can have the promise of perpetual motion. Not so - all that is happening is that we are learning how to avoid a wasteful disordering in the conversion process.

Fyz

Just two short comments and both are formal based on simple logic.

- the 2nd law of thermodynamics is not the same as (all the laws of) thermodynamics.

No one is in doubt with the 1st law...

- However, while one is arguing for validating the 2nd law, at the same time one cannot argue with that.

As the rest is concerned, I agree since when there is an ordered system #1 and there is an other one, #2, the transition process of #1 -> #2 assumes a disordered state, whatever it is.

So, one can not abandon a series of disordered states regardless how it was developed.

Now, the question is that whether it is reversible in a cyclic process w/o hysteresys.

I'm probably being dense, but I don't understand what you said here. It's probably something that is obvious to you because so familiar with your presentation and specialised language.
Would you (or anyone on your wavelength) care to reword it and separate the assumptions and and logical steps so that others can follow the drift? It may be that we are also talking different languages - where I come from, "validating" means "doing work to demonstrate the truth of something". From where I stand, the second law is already well validated - in the form expressed by Clausius, and as an expected result (in the formal statistical sense of "expected"), so I can't think that is what you mean.

Apologies and thanks

Fyz

Sorry, my English is poor.

The Carnot cycle is a theoretical machine, and we accept it.

The second law of thermodinamics says: impossible convert heat to work 100 percently. (Thompson 1850)

If I describe a machine, it convert heat energy to electric energy 100 percently, with real chemical and physical processes, based first law of thermodinamics, we have to find where the error is in it, or we can't it, the second law is fail.

Thanks, that is clear. So far, there is no evidence that the second law fails. My remark was addressed to those who might argue that this means you can't convert chemical energy to electrical energy with very small loss. The only reason for submitting #13 was that there seemed to be some contributions that assumed that chemical energy had the same characteristics as thermal energy (as regards conversion efficiency to electricity). But I appreciate that this may only have been a misinterpretation (on my part) of ambiguities in the wording of the posts

Regards

Fyz

"My remark was addressed to those who might argue that this means you can't convert chemical energy to electrical energy with very small loss."

You can't convert all chemical energy to electric energy, only free enthalpy (Gibbs potencial). But you can get back all all thermal loss with a reverse Carnot cycle.

If the cell produces more electricity, than refrigerator needs, you can convert heat energy to electric energy. In this case what about second law?

Sorry about the chemical shorthand, you are of course correct there.

But the heat is not converted 100% to electricity - it's just that you can use the ordering of the electrical energy to transfer heat using the heat-pump (refrigertor). This is only a matter of using appropriate definitions for the second law. (The best net result would be that you get the same electricity out as you put in - which is not a problem).

Regards

Fyz

Heat is converted 100% to electricity.

We put 100 unit heat into machine in first step. 100 unit heat is converted chemical energy. It is possible, no problem. After we convert 100 unit chemical energy to 80 unit electric energy, and 20 unit heat stays in the cell. We need 4 unit electric energy to pump back heat to regenerator from 961 K to 1176 K.

We have got 76 unit eletricity, and pump back 20 + 4 unit heat energy.

In the next step we need 100 unit again, but we have 24, so give 76 unit to machine!

At the end, we put into the machine 76 unit heat energy and take out 76 electric energy in every steps.

This basically violates second law of thermodinamics. What about entropy?

Entropy of thermal energy is not same entropy of electric energy.

This is the main problem of dkg11hu with this theory.

Except for the little matter that you pointed out earlier: of the thermal -> chemical energy conversion, the maximum proportion that can be available as free enthalpy is the same as can be converted to ordered motion (or electricity).

Thanks for highlighting another nice amusing way to hide the problems

Fyz.

Sorry, I said chemical energy -> electric energy is not 100%, because we get only the free enthalpy from the cell. The bound energy stays in cell as thermal energy.

We can convert 100% thermal energy to chemical energy.

"We can convert 100% thermal energy to chemical energy." That may be true if you define 'chemical energy' widely enough. But you can't go on to convert more than the appropriate proportion to electrical or mechanical energy, which is where the entropy limitation applies

Fyz

Sorry for my english!

On decomposition temperature all thermal energy decompose the lithiumhidride to lithium and hydrogen. (like water boiling) This is the chemical fact.

Lithium and separated hydrogen have chemical energy, we can convert this to electric energy in a Li|LiH|H2 cell. O.K., we can get only free enthalpy (Gibbs potential)

You can't use theory of entropy against this "second type perpetuum mobile", because if second law of thermodinamics is broken, entropy also.

As dkg11hu said:

"- However, while one is arguing for validating the 2nd law, at the same time one cannot argue with that."

Don't forget! The second law of thermodinamics ~ concept of entropy!

There is no second law, there is no concept of entropy!

"Where does the energy come from?"

From outside. This is second type perpetuum mobile, not first type.

"Over the years there has been more than one example of second law violation"

Wrong. All of the "2nd law violations" reported in the mainstream media in recent years turned out to be misinterpretations by news journalists who don't understand the 2nd law (specifically the Fluctuation Theorem of the 2nd law). As a scientist interested in the 2nd law, I read the original scientific articles (published in peer-reviewed journals) and invariably found that the authors specifically point out that the reported phenomena did *not* violate the 2nd law. Their results deserved attention simply because they provided new demonstrations of the Fluctuation Theorem (which had previously been out of reach due to lack of sensitive detection techniques). The 2nd law allows for short-lived molecular-scale deviations from statitistically average behavior. But it also specifies that summing such random fluctuations in order to accomplish macro-scale work has infintesimal probability of occurring.

So the new "urban legend" about commonplace violations of the 2nd law of thermodynamics comes from misunderstanding and from the tendency of the media to sensationalize. I challenge anyone who disagrees with me to provide web links to any credible sources supporting a 2nd law violation claim.

Articles, Patents about thermally regenerated cells:

www.scholar.google.com keywords:thermally regenerated ionic hydride cell

I hear TEC , Peltier devices work very well to convert heat into D.C. power. So much so that the military use propane heated packs using TEC devices to charge batteries in the field.Does anyone know what the efficiency is for TEC power generation ?

Laserlover

Off the top of my head, I'd say very low. In cooling use these are 5-10% efficient, and that is with one side freezing, and the other being blower cooled. To charge batteries efficiently you would need to provide high temperature differential -- and even then ,the efficiency would be very low in comparision to a normal battery charger. Of course, if you have nowhere to plug in -- then efficiency is not in the driver's seat.

Anyway..

Thermally regenerated cells lose energy with cooling, because temperature of cell is lower than regeneration.

What is the situation theoretically, if I can regenerate a cell below working temperature of it?

Pure Li!LiH|H2 cell works 961 Kelvin.

But K + LiH -> K + Li + 1/2H2 reaction starts on 573 Kelvin!

Li-K phase diagram

http://secondlaw.acs.hu/K-Lifazisdiagram.jpg

What is the situation if I use this theoretical process without temperature difference?

http://secondlaw.acs.hu/sematikaeng.gif

Electrochemical energy conversion by-passes second law ofthermodynamics
Oman, H.

This paper appears in: Applications and Advances, 2001. The Sixteenth Annual Battery Conference on
Publication Date: 2001
On page(s): 245-249
Meeting Date: 01/09/2001 - 01/12/2001
Location: Long Beach, CA, USA
ISBN: 0-7803-6545-3
References Cited: 6
INSPEC Accession Number: 6984373
Digital Object Identifier: 10.1109/BCAA.2001.905132
Posted online: 2002-08-07 00:18:20.0

Abstract
New spacecraft will explore the outer regions of the solar system where sunlight is too weak for generating the required electric power. Europa, the orbiter of Jupiter's moon, will require 210 watts of power for its six years of post-launch lifetime. Low-power radioisotope-heated thermoelectric generators have powered 26 spacecraft on deep-space missions, but their efficiency is only around 6%. Developing a larger radioisotope general-purpose heat-source (GPHS) for the new missions is not feasible in today's social environment. One candidate for converting heat to electric power from the existing radioisotope heater is the alkali-metal-electrochemical (AMTEC) converter. With its heat source it would weigh 18 kg and deliver 210-watts with an efficiency of 21.6%. Lifetimes in test are now over 60000 hours. The alternative energy converter is the free-piston Stirling engine in which the pistons are precisely supported with flexing diaphragms so that pistons do not have any moving contact with cylinder surfaces. Maintenance-free operating lifetimes of 100000 hours have been demonstrated. A 210-watt Stirling-cycle converter and its GPHS would weigh 16.1 kg and have an efficiency of 26%. An interesting new approach could be a combined-cycle power source in which the Stirling engine is topped by an AMTEC converter

The abstract cites better conversion efficiencies for the Stirling engine than for the electrochemical conversion. The paper is not freely available. So the question is "what does Oman say that leads you to the above interpretation?" Thanks in advance for your clarification