Protein nanowires + Geobacter + humidty = electric potential

  • #1
jim mcnamara
Mentor
4,688
3,630
https://phys.org/news/2020-02-green-technology-electricity-thin-air.html

I am not competent to judge this (what seems very edgy to me) article. Basically it says: a ten micron thick protein layer with Geobacter on the surface and protein nanowires arranged in a mesh, when exposed to humidity, generates electricity.

Maybe @TeethWhitener who is knowledgeable in nanoscience can help.

Source:
Power generation from ambient humidity using protein nanowires, Nature (2020).
DOI: 10.1038/s41586-020-2010-9 ,
https://nature.com/articles/s41586-020-2010-9

On a lighter note - if this has merit the Pacific Northwest will become Power Central (with a capital P and capital C) for the Western US.
Forecasts for places like Eugene OR, talk about 'sun breaks'. A few minutes when you can see the sun.

I think @OmCheeto or @BillTre may be able to comment on the humidity aspect of life up there. I live in a desert...
 

Answers and Replies

  • #2
Borek
Mentor
29,167
3,836
It is not nanowires that make me doubt, but the thermodynamics - they have not explained where the energy comes from.

"Out of a thin air" would make a nice twist if it was published on April 1st.
 
  • Like
Likes russ_watters and Bystander
  • #3
fresh_42
Mentor
Insights Author
2022 Award
17,643
18,296
My thought was as I read it: For an industrial scale we would need much humidity, hence solar or geothermal energy first, plus whatever those bacteria eat.

Funny idea, but I would put my money on algae first.
 
  • #4
chemisttree
Science Advisor
Homework Helper
Gold Member
3,711
704
I’ve seen a potato provide enough electricity to power small electronics too!😂

I think ultimately you will find the secret to this redox battery is hiding in the “surface chemistry” of the wires or some redox occurring at the electrodes. I prefer potatoes to smelly sulfurreducens anyway!
 
  • #5
Borek
Mentor
29,167
3,836
I’ve seen a potato provide enough electricity to power small electronics too!😂

Sure, but there is a dissolving wire there, it is obvious where the energy comes from (and when it will end).

I think ultimately you will find the secret to this redox battery is hiding in the “surface chemistry” of the wires or some redox occurring at the electrodes.

In both cases something would be consumed. The way the article is written it doesn't say what is consumed to produce the energy, it just juggles humidity, nanowires, proteins and geobacters.

This is level of reporting that fits tabloid.
 
  • Like
Likes russ_watters
  • #6
chemisttree
Science Advisor
Homework Helper
Gold Member
3,711
704
But it’s “Nature!” We must submit to it...

The way its written it is hard to distinguish it from a perpetual motion black box or free energy.
 
  • Like
Likes berkeman and Borek
  • #7
TeethWhitener
Science Advisor
Gold Member
2,432
1,977
I’ll look at the full paper at work tomorrow when I have access. There’s a fair amount of work being done right now on evaporation and condensation-based energy harvesting (full disclosure: I pitched a program on nanoscale electrokinetic phenomena last year that didn’t get funded :rolleyes:). From what I can tell from various press releases (this one in particular), this device falls into the same category. I’m not sure how they’re maintaining their moisture gradient, but apparently neither are they. Hopefully the paper will be clearer.
 
  • #8
berkeman
Mentor
64,121
15,322
But it’s “Nature!” We must submit to it...
You beat me to posting that! Is there a difference between "Nature" and "nature" journal articles?
 
  • #10
BillTre
Science Advisor
Gold Member
2022 Award
2,207
7,327
A couple years ago, for while, I became interested in geobactor making these little nanotube things to apparently conduct electrons from an anoxic layer in sediment to the better oxygenated surface of the sediment.
This allowed the bacteria deep in the sediment (a few centimeters) to make better use of the local resources they had at their disposal (as well IIRC) improving nourishment of the bacteria along the filaments leading to the better oxygenated higher up regions.
It was not clear to me (did not have access to a lot of the journals) how this was happening at a molecular level, but it was interesting. Since I could not figure out what was going on and my journal access was limited, my interest in the subject waned.
I could understand how an electron pipeline between an oxygenated area and non-oxygenated area could be beneficial in a fairly straightforward way, it was not clear how this could benefit a bunch of bacterial along the filament and still provide benefit to the most deeply buried bacteria.
It seemed to be doing more than just conducting the electrons.

This case seems to be doing something similar, maybe conducting electrons to a surface where they are dissipated to a humid atmosphere by shedding molecules with a charge.
 
  • #11
TeethWhitener
Science Advisor
Gold Member
2,432
1,977
It was not clear to me (did not have access to a lot of the journals) how this was happening at a molecular level, but it was interesting. Since I could not figure out what was going on and my journal access was limited, my interest in the subject waned.
It’s still an open question. It looks to be some combination of remarkably high proton conductivity coupled with electron conduction through stacks of cytochromes, but that’s just a guess. I have a number of colleagues working on Geobacter for that very reason.
 
  • #12
TeethWhitener
Science Advisor
Gold Member
2,432
1,977
First glance at the paper:
1) Their device consists of a gold electrode as a base, a film of protein nanowires, and a small gold electrode at the top that does not cover the nanowires completely and allows them access to humidity in the air.
1) Power density is about 4 mW/cm3
2) It's not photovoltaic.
3) the I-V curve does not pass through the origin. This is usually indicative of leakage current or charging of some kind. But the authors assert that it isn't charging (at least not transient charging) because the effect lasts for >12 hours.
4) It's not coming from oxygen or nitrogen in the air, and they did some work to support the assertion that it's not coming from chemical changes in the nanowires.
5) Stable DC voltage of around 0.5V for 2 months.
6) There's a gradient of water adsorption in the device that correlates with the open circuit voltage. This goes away if the top electrode is made to cover the protein nanowires entirely.

The authors' best guess is that the nanoporous structure of the nanowire mesh is extremely slow to saturate with adsorbed water, and the distribution of carboxyl groups in the structure is such that the adsorption gradient corresponds to a potential gradient in the device.

A brief primer on the nanoscale electrokinetic effect that is likely responsible for this: at a solid/electrolyte interface, the solid has a surface potential which impacts the distribution of ions in the electrolyte. This ion distribution has a characteristic length scale (the Debye length), beyond which the ions effectively screen the surface potential from the bulk electrolyte. The Debye length is on the order of 1-50 nm for typical electrolyte strengths. If you shrink nanochannels/nanopores down to this scale, the linearized Poisson-Boltzmann equation that governs the behavior of the electrolyte no longer works, and nonlinear effects start creeping in. Large boosts in the efficiency of the electrokinetic effect are observed, and you can exploit lots of transient gradients (both chemical and physical) in these types of systems to harvest energy (my own interest was in pressure gradients for tidal/current energy harvesting).
 
  • Like
Likes jim mcnamara
  • #13
BillTre
Science Advisor
Gold Member
2022 Award
2,207
7,327
A brief primer on the nanoscale electrokinetic effect that is likely responsible for this: at a solid/electrolyte interface, the solid has a surface potential which impacts the distribution of ions in the electrolyte. This ion distribution has a characteristic length scale (the Debye length), beyond which the ions effectively screen the surface potential from the bulk electrolyte. The Debye length is on the order of 1-50 nm for typical electrolyte strengths. If you shrink nanochannels/nanopores down to this scale, the linearized Poisson-Boltzmann equation that governs the behavior of the electrolyte no longer works, and nonlinear effects start creeping in. Large boosts in the efficiency of the electrokinetic effect are observed, and you can exploit lots of transient gradients (both chemical and physical) in these types of systems to harvest energy (my own interest was in pressure gradients for tidal/current energy harvesting).
It seems to me that for this effect to be maintained for such long periods, the charge has to go somewhere so that it does not build up and inhibit the effect.
My guess above, is that some charge gets shed as gaseous molecules in the humidity and can then diffuse away. However, I don't know if this is reasonable or even possible.

The electronics of living things can be quite complex and interesting.
 
  • #14
zoki85
1,187
227
I’ve seen a potato provide enough electricity to power small electronics too!😂
I've also heard that and was enthusiastic to test it. I tried that and even more (combinations of potatoes,lemons, various electrodes to stick in parallel or series threads).
Complete disappointment...Less than miliwatt in best case. I destroyed few kilos of good food in a process


It is not nanowires that make me doubt, but the thermodynamics - they have not explained where the energy comes from.

"Out of a thin air" would make a nice twist if it was published on April 1st.

It's possible from "a thin air". The device is called a windmill :)
 

Suggested for: Protein nanowires + Geobacter + humidty = electric potential

Replies
13
Views
425
  • Last Post
Replies
14
Views
1K
  • Last Post
Replies
2
Views
911
  • Last Post
Replies
19
Views
1K
Replies
9
Views
1K
  • Last Post
Replies
7
Views
335
Replies
1
Views
325
Replies
5
Views
734
Replies
9
Views
2K
Replies
20
Views
3K
Top