Scientists build circuit to generate limitless low-voltage power from graphene | Hacker News Reader

Scientists build circuit to generate limitless low-voltage power from graphene

thebrighterside.news

22 pointsdanboarder12 comments

>Knowing this, Thibado’s group built their circuit with two diodes for converting AC into a direct current (DC). With the diodes in opposition allowing the current to flow both ways, they provide separate paths through the circuit, producing a pulsing DC current that performs work on a load resistor.

Always a bit hmmm when I see something simple like a rectifier spun out in a way that eludes that they invented some revolutionary new circuit.

Yeah this is hella sketchy.

>We also found that the on-off, switch-like behavior of the diodes actually amplifies the power delivered, rather than reducing it, as previously thought

Wat. Why is this crap on the front page?

The journal paper is linked in the article if you want to read it. For low-voltage devices it seems reasonable to me.

Fluctuation-induced current from freestanding graphene https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.0...

Unfortunately I don't have an institutional login, or else I would be able to comment better. :(

But it sounds to me from the abstract like the result is not significantly different from the thermal noise voltage on a resistor? I don't expect that they would be able to extract any work from the system, unless there is a temperature difference somewhere.

There is a version on the arXiv: https://arxiv.org/abs/2002.09947

"harvesting energy from graphene is controversial because it refutes physicist Richard Feynman’s well-known assertion that the thermal motion of atoms, known as Brownian motion, cannot do work. Thibado’s team found that at room temperature the thermal motion of graphene does in fact induce an alternating current (AC) in a circuit, an achievement thought to be impossible."

So is this effectively a micro cooler? (Extracting thermal energy?) I experimented with TEC Peltier modules/cells for converting solar concentrator heat to electricity, it's not particularly efficient but it works when there is a sufficient temperature differential.

https://en.m.wikipedia.org/?title=Peltier_device&redirect=no

Do you mind expanding on your experimentation?

For an off-grid cabin in the Yukon I've always though about having a ton of TECs sitting on or very near the wood stove (which burns for 8+ months a year), with some piping and coolant running outside to a radiator (where it's -20C to -45C for 5+ months).

I expect a least a few hundred degrees C of temperature difference, and I wonder about charging the batteries to augment the solar.

As I recall the voltage was similar to a AA battery (per module) with a 30+ degree difference on each side of the cell, so a lot of modules could be assembled in an array to generate useful power. A lot of small boat/RV refrigerators use these for their direct thermal effect (one side will get ice cold when powered). My experiment was a smaller scale parabolic solar trough design with a line of modules along the focus point since I needed to heat water anyway to regulate temperatures in an aquaponics system (fish farm). Side note, I've seen successful systems out there that use Stirling engines to power a generator from the concentrated solar heat.

With such a high differential you might reach better efficiencies using a Stirling motor.

"clean, limitless, low-voltage power" the title omitted a pretty important word there.

Thanks - I added 'low-voltage' to the HN title even though it's not in the linked article because I agree with you, it's helpful.

https://news.ycombinator.com/item?id=30494938

Reply on news.ycombinator.com