I'm sorry you feel that I am always talking directly to you, but I am not. And, for the record, the voices in your head - they aren't talking to you either, those voices are talking to each other.
Electricity generated with water, salt and a three-atoms-thick membrane
- Thread starter bertus
- Start date
So am I to assume that you aren't talking directly to me now?
key word above has been highlighted. As in, I am not ALWAYS talking to you, but I may talk to you SOMETIMES. See how that works? If you are having trouble understanding the difference between always, sometimes and never - you may be troubled by conditional statements elsewhere in your life.
You may have dropped the ball on some opportunities in recent years. For example, when your wife said "not tonight" some years ago, she likely DID NOT mean "not ever". Too bad for you.
You just need the right inspiration. I'm sure you'll get your mojo back soon.
Back to the original topic:
I've been thinking heavily about the article since yesterday. If their claims are true, someone has a goldmine on their hands.
But, I am ready to call BS -- right up there with cold fusion. Here's why:
The concept of passively separating ions, i.e. the movement of positive ions from one side of the membrane to the other, while preventing the passage of negative ions, implies a decrease of entropy of the overall system (two volumes with separate ions has less entropy than one equal volume with the ions mixed). This further implies there must be an addition of energy greater than the energy gained by the transfer.
So, in this respect, without an external input of energy greater than that gained, the system would operate over-unity. We all know this is impossible, no matter how much one wishes it to be so.
Edit: Statistically, it is possible that the ions self-organize according to charge. Practically, it is impossible -- just as there is a non-zero possibility that a broken coffee cup on the floor could magically jump up on the table and reassemble itself.
I've been thinking heavily about the article since yesterday. If their claims are true, someone has a goldmine on their hands.
But, I am ready to call BS -- right up there with cold fusion. Here's why:
The concept of passively separating ions, i.e. the movement of positive ions from one side of the membrane to the other, while preventing the passage of negative ions, implies a decrease of entropy of the overall system (two volumes with separate ions has less entropy than one equal volume with the ions mixed). This further implies there must be an addition of energy greater than the energy gained by the transfer.
So, in this respect, without an external input of energy greater than that gained, the system would operate over-unity. We all know this is impossible, no matter how much one wishes it to be so.
Edit: Statistically, it is possible that the ions self-organize according to charge. Practically, it is impossible -- just as there is a non-zero possibility that a broken coffee cup on the floor could magically jump up on the table and reassemble itself.
I think that is why the researcher is looking at only one pore, and one "slosh" of water movement. I don't know how a practical application will allow the flow to stop and maintain charge separation.
I think of it as trying to capture the energy of the waves in a trough of water after it is bumped and the researcher looks at the peak-to-peak potential difference of the first wave - the constraints of a real system becomes much less of an opportunity.
I think one of the fallacies lies in that 'free ions' don't translate into 'free electrons' -- which is a requirement to produce electricity. Another is this:
Let's humor the authors and assume, statistically, more positive ions can move through the membrane than negative ions. Over a short period of time, the volume of one side gains a positive charge (not really -- just an excess of positive ions) and the volume on the other side gains a negative charge.
Well, very quickly, there is going to arise a net force preventing the positive ions from further propagating to the positive side -- positive charges repel. Therefore, 'charged' fluid will have to be removed from proximity of the membrane, and replaced with uncharged fluid, to encourage the continued flow of ions across the barrier. I believe the energy required to cause this movement of fluid will require more energy than that gained. Thus, an overall increase in entropy as expected -- and no net gain of energy.
Let's humor the authors and assume, statistically, more positive ions can move through the membrane than negative ions. Over a short period of time, the volume of one side gains a positive charge (not really -- just an excess of positive ions) and the volume on the other side gains a negative charge.
Well, very quickly, there is going to arise a net force preventing the positive ions from further propagating to the positive side -- positive charges repel. Therefore, 'charged' fluid will have to be removed from proximity of the membrane, and replaced with uncharged fluid, to encourage the continued flow of ions across the barrier. I believe the energy required to cause this movement of fluid will require more energy than that gained. Thus, an overall increase in entropy as expected -- and no net gain of energy.
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Yes, that is exactly why they don't want to look at the diffusion, just a one-way path through the pore one time. This is not science, it is business - the business of getting research funding, publicity and tenure.
Oh, you were passed like you were standing still quite some time ago.
As a coworker once commented: "The reason to get a grant is to get another grant".
Without resorting to baseless personal attacks, no, I won't.
I finally watched the little video they provided and I've become slightly less skeptical. I thought previously, incorrectly, that the current was generated in the membrane itself, kind of like a solar cell. It's not. The current is the movement of the ions themselves perpendicular to the face of the membrane. So it's a lot easier to visualize a large current flux across the 1m^2 surface than at the edges of an ultra-thin membrane.
I also noticed the wording, "... an estimated power density of up to 10^6 watts per square meter". We don't know the conditions at the "up to" point. Was it concentrated brine at 100°C instead of the presumed seawater at 10-20°C? And if the original paper had any adjustments for practical considerations, they didn't make it into the abstract.
The basic thermodynamics still make no sense to me. As also noted by @WBahn, the states before and after a MW-sec of operation just aren't different enough to account for the energy allegedly produced. I admit I haven't done the state calculations.
From the 1954 Nature article:
"WHEN a volume V of a pure solvent mixes irreversibly with a much larger volume of a solution the osmotic pressure of which is P, the free energy lost is equal to PV. The osmotic pressure of sea-water is about 20 atmospheres1, so that when a river mixes with the sea, free energy equal to that obtainable from a waterfall 680 ft. high is lost. There thus exists an untapped source of power which has (so far as I know) been unmentioned in the literature."
Interesting, at least.
I also noticed the wording, "... an estimated power density of up to 10^6 watts per square meter". We don't know the conditions at the "up to" point. Was it concentrated brine at 100°C instead of the presumed seawater at 10-20°C? And if the original paper had any adjustments for practical considerations, they didn't make it into the abstract.
The basic thermodynamics still make no sense to me. As also noted by @WBahn, the states before and after a MW-sec of operation just aren't different enough to account for the energy allegedly produced. I admit I haven't done the state calculations.
From the 1954 Nature article:
"WHEN a volume V of a pure solvent mixes irreversibly with a much larger volume of a solution the osmotic pressure of which is P, the free energy lost is equal to PV. The osmotic pressure of sea-water is about 20 atmospheres1, so that when a river mixes with the sea, free energy equal to that obtainable from a waterfall 680 ft. high is lost. There thus exists an untapped source of power which has (so far as I know) been unmentioned in the literature."
Interesting, at least.
