Energy density (storage capacity) does seem to be in range of Lithium Ion batteries, better than some, but still around a factor 7 or so worse than the highest density there (but slowest to discharge). Considering the extra effort managing the batteries (Boeing, Tesla,...) you might just come out ahead already.
There also exist hybrid supercapacitors, which use a chemical reaction but act like capacitors. The best use of high-power capacitors is not as a replacement, its as a supplement. Current technology is not quite sufficient, but ideally it would mean that anything under a 20 minute drive could run off just the capacitor, which could(with sufficient infrastructure) charge in under a minute. It's not quite filling up on gas, but its closer.
I would like to see more investigation into turbine powered cars again, it may be more feasible now to build a car like we build trains (A prime mover generates energy for locomotive motors). I think the best way to transition from gasoline to electric would be to take advantage of existing infrastructure and make hot-swappable battery units. For medium drives you use batteries, which can be switched in a garage with a capacitor bank for short drives, or a unit with a small battery, a helicopter turbojet and a gas tank (Which, ideally, would run at a higher efficiency than an ICE).
The reason we haven't used turbines in the past as far as I know is mostly the start-up times and inability to idle. They don't really slow down, so sitting in stop and go traffic you engine is basically still on full blast. Ameliorate that with a battery and you're good to go, hopefully.
Chrysler made a turbine powered car in the Sixties. It would run on nearly anything. Unfortunately, Chrysler never pushed it to mass production, then the oil embargo put paid to that idea. But it was one of those beautiful futures of the Sixties.
Fascinating. At the end there's a link to an earlier Fiat I did not know had existed: http://en.wikipedia.org/wiki/Fiat_Turbina (the photo reminded me of something familiar, took me a bit to figure out it was a guppy fish ;-)
Well, maybe not if you try to directly couple them to the tires. You might have better luck if you try powering a generator to charge batteries. What do you mean by "highly polluting"? Highly polluting compared to what?
"Gas turbines operate best at full-power steady state conditions where they are at their highest fuel and emissions efficiencies. Deviations away from this tuned set point result in significant inefficiencies (particularly with NOx emissions)"
The graph relates to intended use not just physical limitations. Backup generators are generally more concerned with cost and matinace issues than efficecy. So they tend to be simpler and have much lower tolerances. That said, the automotive market is huge so if they ever became popular for say plug in hybrids something in the 30-40% range is vary possible even at 100hp.
>Energy-wise, we’re talking about 1.36 milliwatt-hours per cm3, about twice the density of activated carbon, and comparable to a high-power lithium-ion battery.
That's not really comparable to any "high-power lithium-ion battery" at all - Wikipedia quotes 250–730 Wh per litre for Li-ion (so 250-730 mWh/cm^3), and a quick calculation with a laptop battery I have on hand agrees - 84 Wh stated in 27x4x2cm = 388 mWh/cm^3.
Combine the graphene supercapacitor with
Korea Advanced Institute of Science and Technology
OLEV and we would soon have clean transportation in the cities. Imagine what that would do for air quality!
Say that you build inductive charging points in the lanes before stop lights. The car/bus stops and charges the supercapitor. EV battery problem solved with little extra weight needed by the car.
Sure a range extending hybrid car with a engine would be needed in the start until more charging points would be available on the country side.
How about catapults, like an aircraft carrier, instead of inductive chargers? You get all your kinetic energy to road speed plus you can regeneratively charge to the limits of tire/road traction. You get the energy for at least two stops and all you need is a little someplace on the bottom of the car for the hook to engage. I'll bet intersections are more efficient too when the intersection can fire off the waiting traffic in short order.
You'll need a little faith that the intersection software won't launch you into cross traffic or pedestrians. And I'll bet you don't need red light cameras anymore once there is the threat of having a Prius launched into your driver's side door at 30mph.
With some cheap ramps, you could get rid of the stops altogether. Have the catapult run cross traffic up to the proper speed, and then jump over the other street and land safely(?) on the other side.
I've long thought that the third dimension was woefully underused in smoothing the flow of traffic through intersections.
At some point this will be pretty killer tech. One of my favorite applications is to put large capacitors into the foundation of a house with solar panels. Back when Maxell was showing of 4.2F car battery sized capacitors we did the math and figured that a house with a 1500 sq ft base foot print could support enough charge to carry it overnight, assuming that you were in a moderate climate (California worked, Minnesota didn't). Once you can go 'off grid' without battery maintenance worries it will become a lot more common I suspect.
In the video they show that graphene can be thrown away in compost bin safely, how is it related to all the warnings we have about nanomaterials being dangerous?
The warnings comparing carbon-nanotubes to asbestos are simply because of the shape of the structure - they are both microscopic needles and our white blood cells don't do a good job of breaking them down.
Not all nanomaterials are dangerous (just as varying sizes of dust are not), but many new materials may adopt unnatural properties that our body doesn't know how to deal with. So there is still handwavyness to it all.
The warnings about nanomaterials are about their applications, not their mere existence. (The rational warnings, anyway.) Graphene is just a form of carbon, like graphite or diamond, neither of which is thought to be particularly hazardous.
Yes, but this isn't a property unique to nanomaterials -- it's a generic risk common to all materials that can produce fine, abrasive dust. My point is this doesn't represent a nanomaterial risk, it's an ordinary risk in which the source happens to be a nanomaterial. Otherwise asbestos could be classed as a nanomaterial risk after the fact.
Is lunar surface material a nanomaterial? It's certainly nasty stuff and it gets everywhere. It's regarded as one of the primary risks in lunar colonization. Does that make it a nanomaterial?
True, it isn't unique to nanomaterials. However nanomaterials and nanomanufacturing have the prospect of creating a lot of long lasting dust on this scale.
Also it has been the case with every round of technology that there are unexpected risks that turn out to be important. It would be a surprise if nanomaterials failed to bear as yet unknown risks. Particularly once you start doping them with a variety of trace elements to get the properties that you want.
True, but for example carbon nanotubes are also just "form of carbon" and they are great for lot of uses, but have about the same effect on human bodies as Asbestos, [1] so asking about this is legimitate.
Having a better conducting, higher surface area electrode is a huge step. BUT it doesn't really change the fact that a carbon based supercapacitor requires an electrolyte to form the double layer, and all existing electrolytes have a breakdown voltage below 5V. What we need is a better electrolyte. In calculating energy storage in a capacitor, the energy increases exponentially with voltage, while linearly with capacitance.
Very cool and batteries 2.0 would definitely change the world. But this vid is a bit one sided. To charge something in an instance means a lot of electricity has to run through the wire in a very short time.
Also, being able to quickly discharge might just be as much of a problem as it is a blessing. Imagine all stored power inside a electric cars capacitor system to discharge all at once..
They won't know until they process this first step into a working device with conductors and all the essential elements of a real storage device. But in principle, a capacitor is a much better storage device than a battery -- no chemical conversions, no limit to charge-discharge cycles, many similar advantages.
They aren't magic. They have a relatively high self-discharge (or leakage depending on how you measure it) compared to say Li-ion/NiMh cells which means basically they piss capacity away slowly.
Don't expect your wonderful supercap car to actually be charged if you leave it sitting there for a few hours.
> They have a relatively high self-discharge (or leakage depending on how you measure it) compared to say Li-ion/NiMh cells which means basically they piss capacity away slowly.
Your claim is premature -- they haven't chosen an insulator yet. The graphene sheets are the conducting surfaces, not the insulating layer. Your claims are about the properties of the insulating layer between graphene sheets, which hasn't been selected yet. It looks like this:
Nanoscale is fun. A measly voltage of 1 Volt across a gap of 100 nm means there's an electric field of 10 MV/m. It's kind of hard to keep electrically charged particles, such as electrons, from moving under that kind of stimulus.
If memory serves, in air the disruptive voltage is 30kV/cm (or 3 MV/m) - above that one gets those sparkly electric arcs that melt metal, intentionally or not. (Other than that, air is an insulator.)
>> Your remark applies to any storage device, including batteries. So it's not an issue that sets supercapacitors apart.
> That is correct and is my point.
No, your point was that supercapacitors discharge faster than batteries because of leakage. But that's not true -- it depends on which insulating material is selected, and that hasn't been decided yet.
Here is what you said: "They aren't magic. They have a relatively high self-discharge (or leakage depending on how you measure it) compared to say Li-ion/NiMh cells which means basically they piss capacity away slowly."
hmm, I was going to jump in with "Capacitors are never more than 50% efficient, because physics" but it seems only if you charge from nothing at a constant current:
You didn't know you could connect a capacitor to an inductor and let it bounce away until resistance slowly drained the power?
And it's not constant current that would hurt you, it's constant voltage. Because the extra voltage bleeds away into the resistance of your components. If you had ideal components without resistance or inductance it would be impossible to actually apply a pure voltage source to a capacitor.
From what I understand, it's fairly expensive. It's tough to make a profit on a phone when the battery costs $500. Costs are surely coming down but I think we'll have to wait before it hits the mass markets. From the wikipedia page on graphene [1]: "On the other hand, the price of epitaxial graphene on SiC is dominated by the substrate price, which is approximately $100/cm2 as of 2009."
I was a bit disappointed that there weren't any numbers in the film, so I looked them up: http://www.extremetech.com/extreme/122763-graphene-supercapa...
Energy density (storage capacity) does seem to be in range of Lithium Ion batteries, better than some, but still around a factor 7 or so worse than the highest density there (but slowest to discharge). Considering the extra effort managing the batteries (Boeing, Tesla,...) you might just come out ahead already.
On the other hand, Graphene apparently also makes Lithium-Ion batteries significantly better: http://www.extremetech.com/computing/105343-graphene-improve...