# I’ve not the knowledge to evaluate this

Nonsense, like that electricity from raindrops? Or a potentially useful source of power?

Here we show that thin-film devices made from nanometre-scale protein wires harvested from the microbe Geobacter sulfurreducens can generate continuous electric power in the ambient environment. The devices produce a sustained voltage of around 0.5 volts across a 7-micrometre-thick film, with a current density of around 17 microamperes per square centimetre. We find the driving force behind this energy generation to be a self-maintained moisture gradient that forms within the film when the film is exposed to the humidity that is naturally present in air. Connecting several devices linearly scales up the voltage and current to power electronics.

What’s 17 microamps at 0.5 volts when it’s at home? 8.5 microwatts is, umm ?? A million cm 2/8.5 to get one watt? 12 sq metres a watt?

I’ve got these numbers wrong, haven’t I?

## 35 thoughts on “I’ve not the knowledge to evaluate this”

1. You numbers look OK to me. To power a house, say 10kW, call it a square 1/4 mile per side. Less extensive if folded up.

2. “moonbeams from cucumbers”?

3. Seems a lot simpler to take the gutter water and pipe it to a tank in your attic, then run through a turbine to get the power when you want it đź™‚

4. That’ll work, Robbo.

After they have killed off 7,000,000,000 people.

A statistic. To save mankind, they have to kill mankind.

5. Robbo

10KW? Either that’s a massive house, or it’s peak? If peak, isn’t that a whole lot (90%+?) wasted?

6. Apols, I’m assuming that heating is gas or something, that might change things.

7. What sort of current or voltage do you need to kill one virion?

(i) Have I got the jargon right? (ii) Are they susceptible to electrocution?

Normally if you are looking for a research grant you cry Global Warming (or Cancer), but just at the mo’ it might work if you cry Wuhan.

8. Yeah, 12 square metres per watt is right.

It’d be lovely if we could make useful energy out of all sorts of forms of natural entropy. Shame we will soon have an entire generation of green warriors who skipped their thermodynamics classes.

9. Volts and amps are misleading; all that matters are watts.

0.5v x 17ÎĽa
= 8.5ÎĽw / cmÂ˛
= 85mw / mÂ˛

A slow USB phone charger uses 2.5 watts. So youâ€™d need 30mÂ˛ of this thing to power your phone.

To charge your electric car overnight (with a 7kw charger), youâ€™d need 84,000mÂ˛ of this thing.

I canâ€™t see any practical uses for such a device.

10. The power still has to come from somewhere, and it isn’t clear in this snippet where.
The best I can guess is it’s using a temperature differential caused by evaporation, which is powered by the ambient air.
Hence this is no different from a thermocouple between two glasses of water: use the electricity generated to heat one, chill the other, and the extra left over to charge your car. Um.

I take it that that are seeking funding? Suckers and minutes I suspect.

11. True, it’s not a useful phenomenon for generating power.

But it’s still *interesting*

Remember, lasers were once useless.

The key issue is where the power comes from. Because if it can continue generating the microwatts for quite a long time, and is small, it’s got application in cheap distributed sensors (who can take the trickle, charge up a small accumulator, and report with a burst o’energy once every hour or whatever) – measuring temp, pressure, etc etc.

12. We keep finding weird and wonderful ways of generating electricity with very diffuse / low power density methods. BFD. We need to develop a big, hairy, high power density, controllable / despatchable, storable method that doesn’t create C)2. It’s called Nuclear. We should put serious effort into new nuclear.

13. 12sqm per watt isn’t necessarily bad news. If it’s got to be laid out flat in a single layer on your lawn it’s useless, but if it can be “rolled up” with a mesh material to generate an air gap, then it might be possible to construct some sort of usable energy source from a box the size of say a garden shed.

It’s more likely than not going to be useless, but I can see enough potential merit in the concept for it to be worth someone putting in the R&D.

14. BiTiN,

Note that this thing relies on having humid air. In winter, the air is dry, so this thing presumably wouldnâ€™t work.

Solar would be a better choice for the use case you describe.

15. “but if it can be â€śrolled upâ€ť with a mesh material to generate an air gap, then it might be possible to construct some sort of usable energy source from a box the size of say a garden shed.”

That sounds a bit like rolling up solar panel so they don’t take up room. This thing must be getting its power from a difference in electrical charges & to continue to do so the difference has to be maintained. To get say 1KW/h out of your shed, the equivalent of 1kW/h has to be going into your shed from somewhere. What & where?

16. https://arstechnica.com/science/2020/02/bacterial-proteins-plus-ambient-humidity-renewable-power/

“The researchers determined that the function of the device required a humidity gradient across the layer of protein meshâ€”they measured about 27 percent saturation at the surface and only 3 percent at the base of the mesh. Some of the water molecules that get absorbed are already ionized, and the rest allow some of the proteins’ chemical subgroups to ionize, releasing protons into the tiny pockets of liquid that form. It’s these ions, the researchers suspect, that provide the ability to move charges through the electrodes.”

“The researchers calculate that if you had a one-meter-a-side cube in which equal space was given to air flow and the humidity-harvesting devices, it could produce a kilowatt of power.”

17. Interesting write up from Ars, that. They seem to have potential for a device that could “run” for 20 hours, but the voltage drops by 30% (what sort of profile?) over that time. Then a 5 hour “recovery” period (How? Dry it out?) and then good to go again. How many cycles?

The researchers’ model suggests that the thing is only operating at 4% of capacity, so your 1 metre cube could generate more than 1Kw. And other proteins seem to produce the same effect.

God only knows.

18. once you roll it or fold it up there will be insulation. Which may â€”probably will, one way or anotherâ€” limit the effect and require power to ventilate or humidify, or cool or warm â€¦

19. What a pity we do not already have inexpensive, abundant means of producing electricity, or a very large quantity of solar batteries which we could call… coal.

20. We should domesticate those electric eels in the Amazon. 500 V no problem, but we’d need an array of interlinked aquaria and a frequency modulator and a…

21. This could solve the problem of watching the telly or listening to CDs in the bath. As this stuff reacts to humidity, just line the tub with it and… er…

22. Thereâ€™s clearly enough here to base our future plans on. No petrol cars from 2027.

23. On this energy in/energy out aspect. Just been looking at water pump figures. The sort of low pressure pump you might use to drain a pool, *. A 1kW pump will move around 3500 litres/hour. As with most mechanical processes you can reverse the sign & less inefficiencies, that’s a ballpark figure of how much energy you could extract from 3500 litres water flowing through a watermill That’s 3Â˝ tonnes of water. That’s a lot of water equivalent flowing through your shed to get 1k/w/h. What’s moving? There must be something moving. From where? Or does this run on magic?

*pumps tend to be rated as running “flat”. Pumping from one reservoir to another without change of level. The pump progressively less the more head they’re pumping. So it’s presuming 3500l/h running through a watermill in an open channel. Obviously there’s a lot mor energy in water with a good head behind it.

24. Hmm. Mebbe. But I don;t think they’re thinking about mechanical energy. Rather, something to do with condensation/evaporation. There’s a lot of energy around a phase change like that.

25. Well, yeah, Tim. But if you’re proposing something that provides a flow of energy rather than a one off discharge, there must be as much energy going into the magic box as out. How are you getting it in there? 1kW of energy flow is something you tend to notice. Like 60 litres/minute of water rushing past. (Why I used the pump analogy)

There’s a way of looking at this sort of thing. Called common sense. Yes there’s a lot of energy around phase changes. That’s what steam engines use. You’d sort of notice a 1kW/h steam engine in a metre cubed box.

Yes, maybe umpteen sq metres of this stuff spread out might do what it says. But if you fold it up, put it in a box, whatever’s going in has to be concentrated enough to fit through a maximum of 6 mÂ˛ of interface 170 WmÂ˛ Of what? Where do the inefficiencies go? There must be some. Heat? If it heats, at what temperature does the whatever it’s doing stop?

26. If it really was possible to run a house independently from a magic protein shed, the statists would never let us do it. They want us beholden to them for our day to day existence.

27. All electricity produced goes to running a fan to circulate air around the contraption.

“We keep finding weird and wonderful ways of generating electricity with very diffuse / low power density methods.”

Don’t get bogged down in the details; they don’t matter. These monthly discoveries are propaganda, to get the public to accept that they can let go of gas and coal.

“Scientists have other things in the wings which will replace them” is the message in these frequent reports. Different tech. Same message.

‘Harvesting energy from the environment offers the promise of clean power for self-sustained systems1,2.’

Absolutely fvcking not!

But some people who read it will believe it is the future. They will squander their resistance. And give government their approval to get rid of gas and coal.

28. @TtC

Yep. Reminds me of Blue Peter or How? bit about generating electricity from a potato. Similar was using a house plant eg weeping fig as a TV aerial

This strikes me as a similar “exciting” experiment for school kids, not a viable Uni R&D project

29. @Gamecock

One aspect of “free renewable” energy that’s never mentioned worries me:

What impact on climate results from 100s of millions of multi-mega watt huge windmills ‘stealing’ the power of the wind?

30. PF
February 18, 2020 at 11:34 am

Robbo

10KW? Either thatâ€™s a massive house, or itâ€™s peak? If peak, isnâ€™t that a whole lot (90%+?) wasted?

Only if you don’t really need that power peak.

31. It’s not even for a massive house. 40amps. Normal for a 2 bed flat.; A massive house would have 3 phase & 120A +

32. The apartment I rented in Italy had a power supply limited to something less than 10A. There is a special low tariff for such. For years I never noticed, but, if you happen run the dishwasher and washing machine at the same time, and then the hot water cylinder comes onâ€¦. well, it all goes off.

33. Ag

OK, so it’s peak. But then that is 90%+ “wasted”. Because that’s 10x the amount of land / kit needed (which is the limiting resource in this instance)? Cheaper to put it through a battery to take care of the peak?

34. It seems to work on the Makwell’s demon principle. Which would be nice.

djc, we were initially limited to 3 kW in Italy, had to pay some huge sum to be allowed to use 6 kW. We still blew the circuit breaker regularly.

35. Andrew M

Sure, solarâ€™s good. Sure, harvesting sound waves is good. Sure, harvesting mechanical vibrations is good. Theyâ€™re all good. Soâ€™s this, possibly.

Itâ€™s very early days. I think itâ€™s neat that it was discovered. Like harvesting micro vibrational energy, itâ€™s unlikely to have application in â€śbig energyâ€ť situations.

Science is neat; discoveries are neat. Even if they donâ€™t immediately lead to new product categories on Amazon đź™‚