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back to article Hemp used to make graphene-like supercapacitors

A group of scientists from the University of Alberta have created a process that makes graphene-like nanomaterials out of hemp waste, suitable for use in supercapacitors. While graphene is already known to be a good energy store, it's also expensive, so commercial supercapacitors use activated carbon electrodes. According to a …

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Anonymous Coward

Supercapacitors are bad .. hmm

Now for the War On Supercapacitors <sigh>

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Anonymous Coward

So I can smoke it?

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Anonymous Coward

So I can smoke it?

As long as you don't inhale........

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Re: So I can smoke it?

Sure. But why would you want to? Industrial hemp ain't got any THC.

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Boffin

ENERGY density, not power

"power density of up to 49 kWatt-hours per kilo"

kW*hr is energy, not power. kW is power.

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Re: ENERGY density, not power

Well said. But a more pressing concern than the terminology is how they manage to go from 49 kWh/kg to 12 Wh/kg.

I appreciate the other stuff that goes into the finished product, so a factor of three (or even ten) difference, but to lose three order of magnitude? Looks more like a typo than anything else.

At 49 kWh/kg you'd have thought that they'd have a game changer for transport and the energy sector on their hands. At 12 Wh/kg nobody is going to bother to get out of bed for that.

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Boffin

Re: ENERGY density, not power

Article is confusing Energy and Power the two links say:

" is its maximum power density, a measure of how much power a given mass of the material can produce. At 60 °C, the material puts out 49 kW/kg; "

And:

"At a very high power density of 20 kW kg–1 and 20, 60, and 100 °C, the energy densities are 19, 34, and 40 Wh kg–1, respectively. Moreover the assembled supercapacitor device yields a maximum energy density of 12 Wh kg–1"

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Anonymous Coward

Re: ENERGY density, not power

49kW from 12Wh I make that 0.88 Seconds to flat.

So if 1KG releases 49kW for 0.88s I make that about 43kJ so enough to raise 115 grams of water from 10°C to 100°C (based on 4.186 J/g°C) so about enough energy for an egg-cup of tea...

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Anonymous Coward

Re: Confusing power/energy

The article doesn't confuse the two terms, it downright contradicts itself.

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Anonymous Coward

Re: We've had this discussion before

"Can we try to get it right next time please?

Energy x Time = Power"

Yes, let us do try to get it right:

Power * time = energy

Energy / time = power.

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Anonymous Coward

oops

lettuce

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Go

More good news for the EV industry.

Lots of good laboratory advances are being made, I look forward to it all coming together on a commercial scale.

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Flame

Re: More good news for the EV industry.

That's the crux of the issue. All these reports of some University that has made some breakthrough yet nothing has actually changed. Getting new battery technology to market is the problem that needs solving.

Each time I read about a new wonder battery I now assume it's just some university professor fishing for the next 10 years of research money. Whilst not actually delivering anything of value.

I have a battery, it contains load of energy and is made from Trinitrotoluene. I just need $1million to work out the details for use in every day life.

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Trollface

Re: More good news for the EV industry.

But following an explosive growth in parcel delivery services, if the Post Office won't deliver it - will TNT?

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Boffin

@NextWeek

I have a battery, it contains load of energy and is made from Trinitrotoluene

That's the whole point of supercapacitors - unlike batteries, which store energy via a chemical reaction and therefore ultimately degrade as the electrodes corrode or recrystallise into dentritic structures, which short-circuit the cell, supercapacitors store their energy in a purely physical manner. The energy density is necessarily orders of magnitude less than that acheivable by batteries, but at the same time allows for more and shorter charge/recharge cycles, so is more suited for things like buffering the energy from regenerative breaking on electric vehicles. It's a case of using the right tool for the job.

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Coat

can't resist

If one of these is on a circuit board and it pops, do you get "magic smoke"?

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Re: can't resist

Sure, but you'd be chilled about it. That should make support calls interesting :)

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Re: can't resist

Chilled out - no! You'd be frantically shouting at your PC because you cant order 17 pizzas without it anymore!

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Re: can't resist

Ticket closed because user appears to be tripping balls.

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Anonymous Coward

Re: can't resist

You might get high from inhaling the toxic fumes of a burning battery but the hemp won't have anything to do with it.

Hemp != weed

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Re: can't resist

Weed = hemp!

p.s. it was just a joke, so don't be such a pedantic killjoy, m'kay?

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I used one of those caps in my radio and now all I get is reggae.

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"I used one of those caps in my radio and now all I get is reggae."

All I get is the Doobie Brothers, Little Feat's 'Willin' and heavy Dub.

If they make one from sulph all you'd get is Motorhead.

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I must use the low THC model. Are sure it just hemp in that radio if you are getting heavy dub ?

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If you want to claim a high capacitance, reduce the working voltage

142 Farads per gram excellent - combine that with the 12 Wh per kilo and we get a maximum voltage of ... 0.78V.

The other nasties are life time and working temperature. Working temperature is usually specified for a life time of 1000 hours (42 days). Life time doubles if you half the working voltage (divide energy stored by 4), or over specify the temperature by 10 Centigrade. We need temperature and life time specs to compare these to existing devices.

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Re: If you want to claim a high capacitance, reduce the working voltage

Not forgetting ESR.

If th ESR is high, then the supercpa just loses everything in heat.

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Re: If you want to claim a high capacitance, reduce the working voltage

Would that actually have to apply in this case? If you have graphene sheet plates you could conceivably have insulator-ene crystaline dielectrics and the normal breakdown 'mechanics' could be moot.

And anyway you could always wire them in series.

When someone works out how to make graphene cheaply (and gets carbon credits into the bargain) we are going to see a technological revolution that will be so disruptive the stock market will be fucked to pieces:

Renewables - store the excess in capacitors.

Potholes in the road - a few sheets of graphene.

Camping - a graphene tent with high pressure inflatable poles will weigh less than the pump.

And it may be that nature can make the stuff already ...

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Anonymous Coward

There's no point trying to get anything meaningful from the figures in the article

...because they are complete rubbish.

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Facepalm

Hemp!

One of those things that used to be grown in the US, before DuPont got Marijuana banned because hemp-based paper was a danger to their wood-paper patents.

Now it is not only a good fuel, it's a good supercapacitor material as well. How long will we suffer for this boneheaded lobbyism?

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Windows

Re: Hemp!

Hmmm “higher than commercially available supercapacitors.” much like the folks who will find this story hilarious.....

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Re: Hemp!

It was used in rope too. But the whole industry went to pot.

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Re: Hemp!

Nah, hemp was impractical as a sea rope because it wicks (you have to tar hemp rope before you can use it at sea), so they went with manila rope instead which didn't wick.

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Re: Hemp!

Hemp is like the swiss army knife of plants

clothes, rope, paper, health food, drugs, supercapacitors. It's probably one of the best crops you can get... Yet still illegal due to it being a 'drug'

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Re: Hemp!

If it's such a miracle plant, why isn't it used more often in countries where it isn't restricted by drug regulations? The main reason is that hemp is rather a jack-of-all-trades plant. It's useful, yes, but it's no miracle maker. Furthermore, it's a tough plant to process completely.

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Re: Hemp!

name one such country. the US forcefully exported it's war on sanity throughout the world

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Facepalm

Re: Hemp!

Strange that so many stores openly promote and sell hemp stuff here (in the US) if it's been banned by The Man.

Really, do you even think to do the slightest shred of fact checking, or do you just assume that if it's bad it must be true?

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Pint

We are all saved!!

Well, it's either that or there is a typo. 46 KW*hr per kilo corresponds to specific energy of around 165 MJ / kg, which is extraordinary. Diesel is only manages 46 MJ / kg.

If it is true I predict electric cars and renewables will be running the world by the end of the decade, and global warming is henceforth a non-issue.

That's what the beer is for: Here's hoping!

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Re: We are all saved!!

Except... diesel is actually a power source.

Batteries etc are just a power store. They have to be charged, and all that leccy has to come from generators (already overloaded) through a grid (which is already overloaded) .

I predict that by the end of the decase, we'll still be using oil as our primary fuel... and not in out flying cars either!

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Mushroom

Re: We are all saved!!

Diesel is also just a 'power store'... just storing as hydrocarbons, the fact it was created millions of years ago by death of plant/animal life is not relevant when comparing the two.

What we need is more fission power stations and some way to store that energy for use in portable devices...

Although I have no doubt by the end of the decade oil will still be our primary fuel for vehicles, I really hope we will be shifting to mostly nuclear for electricity generation.....

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Anonymous Coward

Re: We are all saved!!

But a high-density battery would transform the usefulness of wind and solar - you could store all that unwanted off-peak energy and use it when needed

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Re: We are all saved!!

"But a high-density battery would transform the usefulness of wind and solar - you could store all that unwanted off-peak energy and use it when needed"

Only if they can fix the problem of self discharge.

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Anonymous Coward

Re: We are all saved!!

Add hemp to your beer recipe, and work to a target of 4.20% ABV?

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FAIL

Re: We are all saved!!

Off peak energy for solar power definition: When the sun don't shine.

For the wind not blowing, it is in the evening when people get home and turn on the A/C and electric cook stove, usually about the time of the setting sun. Also in the early morning, when people are getting up and getting ready for work. The sun low on the horizon on both occasions. neither are really available, when you need them the most.

Hydro? Global warming is turning the water source for that into mud flats.

How's that nuclear looking now, huh?

The last member of the human race, because of our arrogance, is gonna freeze to death, starving and naked in a cave, shortly after s/he burns the last stick of wood in existence.

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Hemp bast is a waste product?

Then what exactly are they growing this hemp for?

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Re: Hemp bast is a waste product?

Hemp is still used for clothing and baskets and the like.

The material has a lot of real current day uses, particularly for fabric.

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Re: Hemp bast is a waste product?

Not really. Cotton beats hemp for most fabric uses, as it's tougher (lasts longer) and softer (more durable) than hemp. And like hemp, cotton naturally wicks.

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Range anxiety

It might have the potential to fix that, but there's still a lot to be done to sort out the infrastructure required to make EVs viable. We needed to install a lot of charging posts and make sure there's the generating capacity in the grid.

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Bronze badge

So that's what they were smoking.

When they put self-destruct capacitors on motherboards, in monitor, subwoofers, flatscreen tellies.

On the plus side (no pun intended), the pavements round here have been host to decent sized monitors and tellies which I've fixed for the cost of a handful of caps.

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Eh?

>the material created by the University of Alberta group has a power density of up to 49 kWatt-hours per kilo

> (...)

>The group says the 12 Wh per kilo density of the assembled supercapacitor (...)

I know, I'm thick....

Is it 49,000 or 12?

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