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Breakthrough In Use of Graphene For Ultracapacitors
Hugh Pickens writes "Researchers at the University of Texas at Austin have achieved a breakthrough in the use of a one-atom thick graphene for storing electrical charge in ultracapacitors. They believe their development shows promise that graphene could eventually double the capacity of existing ultracapacitors. 'Through such a device, electrical charge can be rapidly stored on the graphene sheets, and released from them as well for the delivery of electrical current and, thus, electrical power,' says one of the researchers. Two main methods exist to store electrical energy: in rechargeable batteries and in ultracapacitors, which are becoming increasingly commercialized but are not yet well known to the public. Some advantages of ultracapacitors over traditional energy storage devices such as batteries include: higher power capability, longer life, a wider thermal operating range, lighter, more flexible packaging and lower maintenance. Graphene has a surface area of 2,630 square meters, almost the area of a football field, per gram of material."
Is this another factor of 2 on top of EEStor's still-unproven claims? How many more breakthroughs is it gonna take before something actually happens?
What is likely (already) happening is that supercap properties are being combined with conventional batteries. Creating supercap-battery hybrids.
A project doing this showed promising results in tests until the partner handling the patent found out they weren't allowed to collaberate with other battery companies after all. Fools...
In my day we had to calculate everything as VWs in the Library of Congress.
That's one of the serious problems with any exceptionally high density energy storage technology. How do you keep the genie in the bottle, and protect the public from the critically stupid in our society.
There was a very cool design for a car whose power source was a high mass flywheel in a magnetic housing. You go to a power station, and the station would spin your flywheel up to some insane RPM rate. The possibility of using this in a hybrid vehicle meant you could get really excellent energy storage and return, it was very efficient.
The only drawback, was that if the bloody thing ever got out of containment, you had a death dealing juggernaut that would buzz-saw a swatch of destruction through the middle of wherever the now flying flywheel was pointed. Then some bright child imagined such a flywheel driven vehicle on a crowded freeway causing a chain reaction of thousands of other similar vehicle, and suddenly you pretty much have a scenario for mass destruction that looks like front row seats to Armageddon.
Whatever technology you finally pick, you'll need to make it very safe, or decide it's a Darwinian herd thinning tool.
Hate to break it to you, but if you replace the ultracapacitor with a battery of the same volume, or, heaven forbid, the same volume of gasoline, you're looking at even _more_ stored energy, and no one's too worried about that.
Because it doesn't have to layers that are insulated against each other?
However, if you're talking about two toiled rolls, soaked in electrolyte, with an insulator between them, rolled up and packaged nicely, then yes, you can use that as a capacitor (we'd all be thrilled about a capacity measurement and some pictures when you try it out, please?).
I doubt those numbers. Capacitors in valve radios were more like 32uF, and typically work at hundreds of volts. Values like 3200uF are used in low-voltage power supplies, not in valve equipment, unless it's some very specialized equipment from the 1950s with hundreds of valves, perhaps.
But you are right that charged capacitors can be dangerous. I myself once got a strong shock from a capacitor that had been disconnected from a circuit for about ten minutes, after that I learned to discharge any capacitor in a high voltage power supply. An innocent looking yet dangerous equipment is the normal photographic flash. There you can find, typically, a 200uF capacitor charged to 200 volts.
http://www.quantumg.net/eeepc.txt
How we know is more important than what we know.
Genda may not of quite nailed it on the head in writing but does have a point: capacitors have the ability to discharge a huge amount of their stored energy at once. All the people I know that used to fix TVs have stories of being thrown across their rooms by forgetting to bleed the charges on (non-super-cap) capacitors and letting something short. In comparison, batteries and gasoline even seem have a limit on the amount of discharge they provide in any period... though a comparable example for gasoline might be to finely mist the all the gas into a well oxygenated room and throw in a match. Wheee! ;)
That said, as it's so fast to charge, hopefully it'll become a practical tech at some point. It'd be great to just be able to plop my laptop/phone/whatever on the tray for a few seconds then walk away with a fully charged battery.
How did they plan to fight the angular momentum?
I wonder how practical is graphene capacitor used as a memory storage cell compare to SRAM or DRAM we have today.
Err ... you do know that one of the main differences between SRAM and DRAM is that the latter uses a capacitor (and fewer transistors) than the former per memory cell, and therefore requires to be refreshed occasionally (hence "dynamic", as opposed to "static" memory which will keep its contents as long as it is supplied with power)?
I'd say that graphene capacitors are as uninteresting as it gets as far as memory technology goes, sorry.
Simple - mount it in a gimbal
The way I'd do it is by having two contra-rotating flywheels, one on top of the other. It doesn't solve all the problems, but it gets rid of the most obvious one.
Reality is the ultimate Rorschach.
Unfortunately, since capacitors are more prone than dry cells to losing energy over time due to internal resistance, this won't eliminate the need for dry cells entirely.
I don't see them replacing batteries at all, but augmenting them instead. Batteries are limited in the power they can absorb. They are much more efficient with storing energy if you spread the charge out over a longer period.
The efficiency of regenerative braking in cars is limited by the ability to pump the energy recovered by the brakes back into the batteries. Lots of energy is generated in a few seconds, but there isn't enough time to force that energy into the batteries.
The big benefit from ultracapacitors will be as a front end to the batteries. They can absorb nearly all the braking energy as fast as the pumps can generate it, and then pump it into the batteries at a rate the batteries like. If the driver accelerates before the energy is pushed back into the batteries, the drive motor would pull energy from the lower resistance ultracapacitor, making life even easier for the batteries.
Aah, change is good. -- Rafiki
Yeah, but it ain't easy. -- Simba
Remove the bottleneck for growth, and the expansion will continue till the next bottleneck stops growth.
In our case, with our 'intelligence' we appear to be stretching all our resources to the extreme... till our growth is limited by food, water, land, and perhaps other resources like oil. Then we either have starvation (of food, or of oil or of whatever) or wars (that knock off population).
Probably my memory playing up. On learning that I was developing an interest in electricity and computers, a local elderly gentleman (in the real, British, sense) gifted to me a large amount of old electrical equipment to play with and learn from
Most of it dated from the mid 40s to early 50s and was 40-50 years old at the time, I learned a lot from it but my memories may be confused as to what came from where. I remember a love of the design of the large tube capacitors with their crenellated electric-blue cases and stamped capacity figures, which was only slightly attenuated when one of them nearly blew my head off...
I have been a user for about 10 years. This ends Feb 2014. The site's been ruined. I'm off. Dice, FU
Actually not.
The RPM rate is so high that flywheels get insanely hot as soon as the vacuum is broken, and it has to deal with friction from the air.
With metallic flywheels, this means it breaks apart, and you've got thousands of bits of white-hot magma flying through the air, in a straight line from the direction the flywheel was spinning. Of course your car is going to turned into swiss cheese, and the two cars directly in front/back of you are likely to get damaged as well, but it's not Armageddon.
With carbon-fiber flywheels, the flywheel material is completely incinerated instantly, and DOESN'T risk turning into such deadly projectiles. HOWEVER, you have to have a very good design to deal with the HUGE amount of unimaginably hot air now erupting out the top of the flywheel housing. Mount it properly, eg. externally, on the roof of your car, with a nice thick base-plate, and your vehicle quite quite likely wouldn't face any structural damage. Though, you can definitely expect to need a new coat of paint.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
Or until we invent fertilizer (18th century)...for food
Or until we invent pesticieds/herbicides...for food
Or until we invent underground farming...for food
Or until we invent land reclimation...for land
Or until we invent skyscrappers...for land
Or until we invent seasteading...for land
Or until we invent lunar colonies...for land
Or until we invent large dams...water, food and power (oil)
Or until we invent water treatment...water
Or until we invent reverse osmosis distillation...water
Or until we invent atmospheric condensers...for water
Or until we invent nuclear fission...for power (oil)
Or until we invent fusion...for power (oil)
Or until we invent photovoltaics...for power (oil)
Or until we invent bio fuels...for power (oil)
Or until we invent direct CO2 conversion to hydrocarbons...for oil (from power)
and a big one is:
Or until we invent a trully good electrical battery, one that stores a lot of energy, has high power density, does not wear out, does not use environmentally harmfull components and is cheap (something like these graphene supercapacitors will be under mass production)...for oil
My point is simple. Humanity ran out of resources about 20,000 years ago. We are designed to be hunter/gatherers. The earth can only support a few million hunter/gatherer human beings. It was only through the invention of agriculture and other technologies that we are able to continue. While we will probably ALWAYS have some resource limitation (probably power) there are technologies that exist now that if used can prevent any Malthusian collapse for the indefinet future.
I don't see them replacing batteries at all, but augmenting them instead. Batteries are limited in the power they can absorb.
Yes, but the limit isn't especially limiting in practice. Power density is important, but any modern battery with sufficient energy density to be useful in the EV industry has plenty of power density. Some types of lithium cells (let's pick A123 since they're well known) have outrageous power densities (hence their use in power tools where you want high torque) but rather poor energy density, yet their energy density is an order of magnitude better than the best ultracaps.
Round trip energy efficiency for lithium type batteries is already on the order of 90%. Even if your hypothetical ultracap system were 100% efficient, you're only looking at an ~11% improvement. But of course your hypothetical system won't be anywhere near 100% efficient, and the cap voltage is dramatically higher and the discharge curve is different, so you have to account for additional power electronics losses involved in moving the charge back and forth between the battery system. And if you just doubled the complexity of your power electronics, you've added significant cost and weight.
In short, I'm an electric vehicle engineer, and I have yet to see a situation where adding caps makes more sense than adding more cells to the battery.
Look up introductory electrical engineering stuff, searching for RC time constant and RC curves. This appears to be a good page.
The overall idea is that charge cannot move instantly through a resistance. Think of a capacitor like a bucket of water, and the resistor a hose hooked to the bottom of the bucket. The bucket can drain only as fast as the hose is wide. And the less water there is in the bucket, the slower it will drain (since there is less weight/pressure pushing on the water at the bottom of the bucket where the hose is.)
Weaselmancer
rediculous.