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 …
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.
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"
This post has been deleted by its author
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.
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.
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.
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 ...
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!
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!
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.....
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.
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.
If this material has superior dieletric performance, could this be a possible new source of energy?
Sheets of the material, placed in VERY close proximity used to 'convert' Casimir Effect to electrical energy, stored on supercapacitors made of the same material, maybe?
>> 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.
I'm not sure I understand these units. For example, MJ = ?
Is it short for Mary Jane, perhaps?
Sorry FlyingPhil, I didn't realise there were people here who didn't know SI units, didn't know how to use google, and didn't know that they didn't know.
So here, let me help you out. Since theregister sets "nofollow" you will have to copy & paste this link into your browser: http://en.wikipedia.org/wiki/Joule#Megajoule
I trust you know how to copy & paste. If not report back. I sure there will be sure to many willing helpers if you don't.
Hi Flibbertigibbet - my post was meant as a bit of a joke, following on from the many other hemp/marijuana/pot/high references.
MJ = Mary Jane = where "Mary Jane" is a slang term for marijuana.
It is a phrase most commonly used in the USA, I believe, and is a quite well-known term there. For example, some say that Tom Petty's song "Last Dance with Mary Jane" refers thus. However, I don't think it is a very commonly used term in UK/Australia/NZ/etc.
"power density of up to 49 kWatt-hours per kilo "
I think you mean 49KW/kg,
Because an ENERGY density of 49kWh/kg would be about 1000 times better then the best battery, and would mean that we would have electric cars with a 1kg battery pack...and a range of 200 miles.
That doesn't rate a short sentence in an el Reg article: that's front page news on the financial times.
"power density of up to 49 kWatt-hours per kilo (depending on temperature), capacitance up to 142 Farads per gram, and able to support current density of 100 amps per gram"
That's nice to know (unit-error not withstanding). But it would have been nicer to give us a comparison with something commonly used like, say, a LiON battery?
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2025
