Micro Energy Harvester Using Brownian Motion

Interesting!
http://spectrum.ieee.org/semiconductors/nanotechnology/turning-information-into-energy

You're not thinking of Maxwell's Demon are you?

It's not an energy harvester as such, but more a conceptual tool used in the study of thermodynamics/entropy.

Back in the early days of transistors we tried to build highly efficient radios. I built one such circuit and powered it by building a twin and rectified the current from the twin to provide the DC supply.

Really? I've looked carefully and can't find a little smiley face.

Did you really use a radio needing microwatts of power to harvest picowatts of radio energy?

Using a crystal set, when you rectify the RF, and filter at audio rates, you get AF plus DC components. You can use the DC to power a transistor amp. Of course you need one close station to get enough power to provide that DC. It is a stock standard circuit rediscovered from time to time.

Get close to a radio station and bring florescent light bulbs and you will have light, too.

However, I would not want to live or work next to such an antenna.

I worked with an EE years ago when he was developing an energy loss detection system for power transmission lines. It appears that people were laying coils of wire near the transmission lines and receiving free energy ,at a cost to the utility company.

Sounds interesting. Can you point me to a circuit or product using this idea?

You wrote, "I heard of a hypothetical device that can harvest energy from random motion of fluid particles (Brownian motion)"

That would be heat.

In one sense you are correct. The complete hamiltonian for a fluid particle must include the translational motion of the particles, which we all know as thermal energy and is given by 3/2KbT and we can call it heat.

However, what this really is an average of all the random motions of the particles. This device would upon impact with one such particle, take its kinetic energy and do work. The problem is that since these motions are random, i.e, they are likely to be going in one direction as any other.

The device was like a turbine that can only spin in one direction..

"Nano" or "pico" might be better adjectives than "micro."

My stab at it.

The motion, being truly random, would be an analogy to a dis-ordered magnetic structure that provides no useful magnetic flux, i.e a magnet thats been heated or shocked to disorder its magnetic structure. No ordered energy motion, nothing to add up to a useful energy field.

Order doesnt generally come from dis-order. Heated gas molecules in a closed volume, I believe, is the best proof, the net pressure across the container is zero, because an infinite number of particles moving extremely fast are all bouncing at random and generate no pressure in any particular direction, except to fill the whole volume. A pressure transducer across the volume would read zero.

Take a semi trailer load of D cells that are mixed at random- whats the voltage from end to end? Poor analogy?

Another analogy, electrical noise voltage from a heated resistor. random noise.

The random movement of fluid particles in Brownian motion is a small-scale manifestation of the larger-scale physical propery called 'pressure'. Energy is the capacity to do work. Work is obtained from the system when a fluid moves from a region at one pressure to a lower pressure.

Is there anything new in this?

YES. This device is supposed to extract energy from a system at a constant pressure and at constant temperature by tapping into the microscopic fluctuations.

This is impossible macroscopically.

Not without extracting energy out of the mix, therefore lowing the temperature of the liquid or gas.

Yes. Extracting useful work from a system without a temperature difference (or any other potential) to drive the process violates the second law.

Now that I think about it, thermodynamic equilibrium is a macroscopic concept.

Does it apply in the small scales of space in the atomic scale?

Also in the time scale of nanosecond and femtosecond.. Does an electron even obey fermi-dirac distribution at this timescale?

Yes, in this instance it would.

Anonymous Hero has really hit the point (twice now)... Brownian Motion is powered by ambient heat. Sure you could extract energy from Brownian Motion and convert it to work, but fairly inefficiently I'd bet, and only for as long as the system remains heated by an external source. If you don't have a heat source your machine will slowly chug to a halt as you extract work and approach absloute zero temperature.

In any case there are probably more efficient ways to tap the ambient heat directly - a Sterling engine springs to mind if you have a cold sink somewhere.

You might investigate the workings of a self-winding wristwatch.

In theory, that is what John Searl's generator did. Investigate the "Searl Effect". The device would utilize heat from it's surroundings, until it reached 4⁰ degrees Absolute. At which point it became superconductive.

Searl reported that he had built several of these devices, a small version was supposedly powering his home.

Interesting reading and difficult to make.

Dragon

The paper's primary claim is that the research provides the first experimental confirmation of a theorem named for University of Maryland physicist Christopher Jarzynski, which relates how adding information to a thermodynamic system (in this case its knowledge of the particles' direction) increases its free energy (the Brownian motion converted to work).

What to do with the femto watts it produces?

That's just the start!

Collect a thousand and you've got one of those big fat PicoWatts that everyones talking about.

(I'm assuming the losses are zero).

Its all relative, you know. This could provide power for a nanoscale machines that will be built in the near future. It obviously won't provide enough power for you to run your .

Crookes Radiometer?

http://en.wikipedia.org/wiki/Crookes_radiometer

I had one half a century ago!

Slightly off topic?

The vortex tube, although it is not "a mechanical device that spins in only one direction," does produce a hot stream and a cold stream, both at lower pressure than the feed. The hot stream has higher enthalpy than the feed, so it might be said that some energy has been harvested, or at least concentrated so it can be useful.

Self-organized bulk thermal separation occurs in the Ranque-Hilsch vortex tube without the intervention of any demon, simply by the axial counterflow geometry. A static, simple device can make macroscopic flow divisions statistically inevitable, even though the velocity of any particle is rapidly changing in both magnitude and direction. The pressure drop at both ends shows that some work has been done, so this is not a violation of the Second Law, just a mitigation of its rigor by some intelligent flow geometry. A cascade of static vortex tubes would not work because of the pressure drop at each stage.

Better still is a dynamically sustained vortex tube cascade. Mechanical assistance creates shear between counter-rotating coaxial radial turbines, and in the free shear layer between the turbines a persistent fractal vascular flow network can integrate the small vortices at the periphery with larger ones converging to the axis, to collect the thermal separation effect (Ranque effect). The hot stream goes radially out, doing work turning the turbines and getting work out of what would otherwise be discharged to the atmosphere as waste heat, and the cold stream goes radially in to axial extraction and (in the case of steam) condensing. The hot stream rotates the turbines, losing enthalpy and dropping into the cold stream, and the cold stream is axially extracted to sustain continuous mass flow through the radial counterflow geometry. Not just energy harvesting, but power harvesting from waste heat. See http://www.freepatentsonline.com/7987677.pdf

Vortex tubes need the gas to be pumped through at very high speed.

You don't get something for nothing, it uses lots of energy to separate hot from cold, it's a type of low efficiency refrigerator.

Certainly at the scale of this picture, you could make a little turbine that would get bumped by one particle but not simultaneously by another. The turbine would have to turn.
It the turbine was very large, relative to particle spacing, then all the bumps would average out at east instant, and the turbine would not move.
So you just need a very small turbine. Any energy extracted would have to slow the particles supplying the energy, and so the temperature of the fluid would go down.

But if you are in an open system (dia-thermal and permeable walls), like a fluid exposed to the ambient for instance, you could extract energy endlessly.. as any energy you extract would flow into the system from the surrounding...

This is very interesting.. How can I build it?

A type of device similar to what you're describing has been analyzed. In the paper I read, the device was essentially a gear with a ratchet that allowed it to spin in only one direction. After all the analytics, it was shown that the device would not function in the way originally thought. It would either spin both directions or not at all, depending on how "tight" the ratchet was, but in any case the device will never do work.

The paper that I linked to proves otherwise.

The article you cited in post 1 doesn't prove otherwise. Read the whole thing...

"You're using your 110-volt outlet to power a camera and a computer, and you have to apply electrostatic forces to block the particle. That means you're applying more than just information," says Amit Lal, who directs Cornell University's SonicMEMS Laboratory."

I guarantee the device can't power the equipment needed to make it work. It doesn't harvest energy, it consumes it. At best the device is a micro heat pump.

Please provide references for you statements. Thanks

I haven't read the paper yet, but I'll do so when I have a minute.

The one I was referring to is the following:

1 The machine

2 Why it fails