Years ago, I remember reading about supercapacitor electrodes made from what would be waste hemp bast fiber. They used graphene as a control. And IIRC, the natural branching structure in hemp (the strongest natural fiber) was considered ideal for an electrode.
How do the costs and performance compare? Graphene, hemp, durian, jackfruit
While graphene production costs have fallen due to lots of recent research, IIUC all graphene production is hazardous due to graphene's ability to cross the lungs and the blood-brain barrier?
Re:Aerogel from fruit biowaste produces ultracapacitors
by m463 on Wednesday March 04, 2020 @04:25PM
(#22488309)
All my life, I've heard people go on and on about the magical properties of hemp.
It's hilarious.
They have these material science level arguments about hemp, yet the same people would be hard pressed to find an alternative use for cotton aside from clothes, or wood pulp aside from ikea furniture.
It's a desert topping, it's a driveway sealant. And the government won't let us have it!
Re:Aerogel from fruit biowaste produces ultracapacitors
by ksdale on Wednesday March 04, 2020 @12:58PM
(#22486013)
I was recently reading a book about Thomas Edison and it mentioned how he sent people all around the world searching for plant fibers that they could use as the filament in light bulbs. IIRC, they settled on a type of bamboo because the structure of the fibers were particularly conducive to their purposes.
Turns out UC Berkeley's got an approach for brewing cannabinoids (and I think terpenes) from yeast, and a company in Germany has a provisional patent application to brew cannabinoids from bacteria. We could be absorbing carbon ("sequestering" carbon) and coal ash acid rain with mostly fields of industrial hemp for which there are indeed thousands of uses.
Re:Aerogel from fruit biowaste produces ultracapacitors
by BubRoss on Wednesday March 04, 2020 @02:10PM
(#22486844)
The article seems like it was written for a high school news paper. It's a shame because it seems like there is real research going on that doesn't depend on the smell of durian or what Anthony Bourdain thought of it.
Re:Aerogel from fruit biowaste produces ultracapacitors
by mrfusion on Wednesday March 04, 2020 @09:19AM
(#22483933)
General capacitor question
If you take a charged parallel plate capacitor and pull the plates farther apart does the energy in the system go up or down?
The equations seem to be geared to how distance affects how much you can charge a capacitor. But if it’s already holding a given charge, I don’t think the basic equation applies.
Re:Aerogel from fruit biowaste produces ultracapacitors
by bananabiscuit on Wednesday March 04, 2020 @09:36AM
(#22484061)
Stored energy goes up. That energy comes from the work done to pull the plates apart (since there is a static electric force attracting them to each other)
Re:Aerogel from fruit biowaste produces ultracapacitors
by hwc on Wednesday March 04, 2020 @10:27AM
(#22484513)
As long the capacitors have a width much larger than the distance between them, the energy stored is (if I recall correctly) linear. this is because the electric field is a constant vector field between the plates.
Once that is not true, you will transition to just separating two charged objects. Use Coulombs law to figure out the force. (Work energy is integral of force over distance).
Years ago, I remember reading about supercapacitor electrodes made from what would be waste hemp bast fiber. They used graphene as a control. And IIRC, the natural branching structure in hemp (the strongest natural fiber) was considered ideal for an electrode.
"Hemp Carbon Makes Supercapacitors Superfast" https://www.asme.org/topics-resources/content/hemp-carbon-ma...
How do the costs and performance compare? Graphene, hemp, durian, jackfruit
While graphene production costs have fallen due to lots of recent research, IIUC all graphene production is hazardous due to graphene's ability to cross the lungs and the blood-brain barrier?
It's hilarious.
They have these material science level arguments about hemp, yet the same people would be hard pressed to find an alternative use for cotton aside from clothes, or wood pulp aside from ikea furniture.
It's a desert topping, it's a driveway sealant. And the government won't let us have it!
AFAIU, when they blend hemp with e.g. rayon it's good enough for underwear, sheets, scrubs.
The government is getting the heck out of the way of hemp, a great rotation crop that can be used for soul remediation.
That's the best pun - or typo - that I've seen in a while.
(Freudian psychoanalytic projections are not supported by neuroimaging)
Turns out UC Berkeley's got an approach for brewing cannabinoids (and I think terpenes) from yeast, and a company in Germany has a provisional patent application to brew cannabinoids from bacteria. We could be absorbing carbon ("sequestering" carbon) and coal ash acid rain with mostly fields of industrial hemp for which there are indeed thousands of uses.
Is the Jackfruit and Durian selected because its spongy properties after being autoclaved?
___tech_thing___ FROM ___mundane_trash___ PRODUCES ___space_magic_thing___!
If you take a charged parallel plate capacitor and pull the plates farther apart does the energy in the system go up or down?
The equations seem to be geared to how distance affects how much you can charge a capacitor. But if it’s already holding a given charge, I don’t think the basic equation applies.
That extra energy is coming from your mechanic effort of separating two plates that attract each other.
What’s the limit? What happens 1 meter apart? 20 meters?
Once that is not true, you will transition to just separating two charged objects. Use Coulombs law to figure out the force. (Work energy is integral of force over distance).
So do it in a vacuum, in complete darkness.