A scientific accident that could change the world | Hacker News Reader

A scientific accident that could change the world

io9.com

464 pointsroachsocal104 comments

Conspicuously missing is any mention of energy density. Who cares about power density. That's juste how fast it can discharge. We don't need capacitors that can discharge faster. All capacitors are already much better than batteries with respect to power. We need capacitors that can store more energy. Capacitors typically suck at that and this article doesn't give any indication that these new ones are better.

Here's a page which provides a bit more information than the OP: http://www.engineer.ucla.edu/newsroom/more-news/archive/2012...

And here's a paper on the subject: http://evmc2.files.wordpress.com/2013/02/laser-scribing-of-h...

ok so here is the only real data I could find. At the end of the paper:

"The LSG-EC can exhibit energy densities of up to 1.36 mWh/cm3 , a value that is approximately two times higher than that of the AC-EC"

1.36 mWh/cm3 = 1.36 Wh/L

If we assume that 1 L of it weights very roughly 1kg. We get 1.36 Wh/kg.

From wikipedia:

"The amount of energy stored per unit weight [in ultracapacitors] is generally lower than that of electrochemical batteries (3 to 5 W·h/kg, although 85 W·h/kg has been achieved in the lab[12] as of 2010 compared to 30 to 40 W·h/kg for a lead acid battery, 100 to 250 W·h/kg for a lithium-ion battery and about 0.1% of the volumetric energy density of gasoline."

This is still less than 1% of the energy density of lithium ion batteries.

There is a big miscalculation: Graphene seems to be extremely light weight. 1 liter of graphene will definitely not weight 1kg. Wikipedia [1] only gives measures for m²: Graphene is very light, weighing only about 0.77 milligrams per square meter.

[1] https://en.wikipedia.org/wiki/Graphene

Graphene is also very thin. If you created a box of graphene, it would naturally have about the same weight as diamond or coal (plus or minus 100%, maybe, but certainly not orders of magnitude less).

Probably not minus 100% :-)

Here[1], the density is said to be as low as 0.03 gm/cc which is the same as kg/liter. That gives a multiplicative factor of 33 over the above calculations, i.e. this could be 33% of the energy density of lithium ion batteries. Not bad.

[1]: http://www.strem.com/uploads/resources/documents/graphene_na...

Energy per liter also is an important factor. Your mobile would float, but it also would be the size of your lower arm. Maybe, you should wear your battery as a jacket or a pair of trousers?

A square meter of a single-atom-thick layer of graphene isn't very relevant. Expect the final product to have a volumetric density in the neighborhood of graphite or diamond.

Probably closer to graphite, as to my knowledge graphite is literally just layers of graphene.

You need to separate each layer with an insulator to be effective, otherwise you could just use graphite.

In the comments they mention about 1/4 the energy density of a lithium ion battery, so yes they don't compete on that measure. But full charging can happen in a minute or two, and you could top up a charge in seconds. Perhaps public areas would have inductive chargers on the wall; you'd just walk over and hold your phone or tablet up to it for a few seconds. Airline tray tables could have an inductive charger built in.

Higher energy densities aren't without issues, as Boeing found out with their 787. A battery like that is basically an explosive and it can be tricky to manage.

Your inductive charging tray tables are terrible for my magnetic tapes and floppy disks. Also, where does it get its energy from? It's much more efficient to walk around with wearable solar panels or to embed them directly into the devices. It may not work well on the north pole half the time but batteries aren't very conductive in those environments, anyway.

When was the last time you walked around with a magnetic tape or floppy disc?

Now - what happens if you put your wallet full of credit cards on it?

To be honest, magnetic strips on credit cards are redundant in a fair proportion of the world as well, especially Europe, although with a notable exception of the US which seems to be seriously lagging behind in this area. I live in the UK and it has easily been over 6 years since I have been anywhere where the magnetic strip has been read rather than using chip & pin (EMV).

I visited the UK late last year and can confirm that your card readers can still read the magnetic stripes on our outdated American credit cards if they absolutely have to.

Unfortunately both types die with exposure to magnetic fields - I accidentally too mine into an MRI scanner. This may not Oruro at a lower field strength with the chip type however.

SYNTAX ERROR UNEXPECTED TO... Oh, :s/Oruro/occur/

Wow. That was a bad one, sorry, and I can't edit it. It was supposed to say: Unfortunately both types die with exposure to magnetic fields - I accidentally took mine into an MRI scanner. This may not occur at a lower field strength with the chip-type card however.

I'm pretty sure he was being sarcastic.

There isn't enough upward facing surface area on your body for solar cells to power anything non-trivial. Also floppy disks?!?

Power usage is going down with every generation. A few watts is quite a bit for a machine with an e-ink display.

For others, maybe nothing but charge sustaining purposes at first.

Guess we're not going to be able to work with our SX-64 portables on planes anymore.

I've heard this argument a few times: "It charges so fast that the density doesn't matter".

What often gets missed is that for it to charge fast, you need to provide a lot of power, a lot more than any current changer and laughably more than any inductive system can provide. Lithium Ion batteries can already max out the power offered by the 10W charger that comes with the iPad and charging off computer USB is often slow (USB is current limit). See Telsa's car charge times on normal wall outlets vs superchargers for another example.

To really reap the benefits of this quick charge technology you either need an infrastructure of ~1000W DC chargers throughout the world or carry something about the size of a desktop computer power supply with you at all times.

Also, you would need customers brave enough to charge that tiny device they are holding in their hands at 1000W. A mobile has about the surface area of a 100W incandescent, so if charging is 90% efficient, your mobile would have to radiate about as much heat as such an incandescent would do in about 3 seconds. It won't get as hot as that lamp, because your phone has a larger heat capacity, but I doubt it would stay cool, either. Given the effect of heat on current batteries, I guess designers would want that phone to irradiate waste heat rapidly.

And that's when everything goes well. You would also need companies brave enough to risk the potential lawsuits if something goes wrong (user wears a pacemaker? Has some metal in his hand, e.g. in a tattoo? Charging accident releases heat that lights clothing?)

Charging capacitors is normally much more than 90% efficient. They're not like batteries, where a chemical reaction occurs during charging. Resistive losses in capacitors are normally negligible. In this case they will probably still be negligible, I'd guess, because of the high conductivity of graphene.

True but you've got to consider the numbers we're looking at here.

As an example an iPhone 5 has a 5.45Wh battery, if you wanted to replace that with a super-cap and charge it to 5V in 20 seconds you'd need to provide ~1000W of power or 200A @ 5V. Even if the super cap had very low ESR, call it 1mOhm, which is extremely low compared to current super-caps, you'd still end up dissipating 40W as heat with ~96% efficiency.

Perhaps phone makers can start making their cases out of aluminum, with enough mass to take the heat. 40W over 20 seconds doesn't sound too daunting.

If you split such an aluminum backplate into two parts you could use them as the power contacts. Then you could have a "coffin" type charger where you put in the phone, then closed a cover to run the charge cycle. Kind of like the cover of a washing machine, to reduce the danger level.

> 40W over 20 seconds doesn't sound too daunting.

It would be 40W _for_ 20 seconds, or 800 Joules, which is a lot of heat, enough to boil 3 grams of water that started at 20C or increase the temperature of 30g of aluminum by ~30C over ambient.

>200A @ 5V

I don't think so. Have a look at the comparison image around 3/4ths of the way down the page here:

http://www.interfacebus.com/Copper_Wire_AWG_SIze.html

14AWG (the small one) is the one rated for 20A which you might find in the power cord for a desktop PC, and is significantly bigger than the wire on your current phone charger. The big one (1/0) is rated for 125 amps. You have to go to 3/0, two sizes higher than that, for 200 amps. 3/0 gauge wire is what they commonly use for the main electrical service for a commercial building.

There is no way they would use a 5V charger if it had to draw that much current. But then you have a different problem: High voltage DC is extremely dangerous because it causes your muscles to contract if you come into contact with it, so your heart stops and you can't move to separate yourself from the electrical source.

20 seconds for a full charge is just unrealistic. Make it 60 seconds, and use a 24V charger, and now you're well within reason.

Your right that the way to solve the current issue is to increase voltage, but that creates a list of other problems, the most notable of which, death, you've already touched on, but here some others:

1) You likely still want USB charging support, so now you need a boost converter in the phone or cable.

2) Your PMIC needs to accept the higher input voltage, and you have to be willing to accept the reduced regulator efficiency from the increase in Vin - Vout.

3) 24V running around in a phone creates a lot of possible problems that you don't have with 3.7V cells. Increased moisture sensitivity, gradient induced oxidation, etc.

4) You still need a ton of power. If you jump to 24V then you still need ~42A to hit a 20 second charge, go to 60 seconds and you need ~327W or 13A @ 24V. That is still a massive charger with 10 gauge wiring (1 conductor is 2x + the diameter of the entire lightning cable).

Keep in mind these are lower bound numbers all around. Reality could be 50-100% higher for power needs. The ESR value I threw out above is also a very optimistic minimum hoping that this new tech has much better ESR characteristics than current super-caps which for large capacity models can be up in the hundreds of mOhms which causes a huge thermal issue.

Its still a long ways from being even remotely reasonable for super caps to replace batteries in high power devices like phones and tablets.

Maybe the charger could also have a super capacitor in it, and would charge it up over time. Then when you hook up your device, you would be getting capacitor to capacitor charging. After all, if these things can charge up fast, then they can also discharge fast.

That would work, but you'd need to use about 0 gauge wire between the devices. If you tried that with something the size of a lightning cable you'd have a decent chance of vaporizing the wire/connectors.

So now all we need is this: http://en.wikipedia.org/wiki/File:CERN-cables-p1030764.jpg

Who cares about power density.

Well, cars do. As evidenced by the use of lead-acid batteries, power density > energy density for automobiles.

Of course, better power density is probably not the main obstacle to using capacitors in a car to replace the battery.

I have the article printed out somewhere, the energy density is in there, about 10 times that of conventional activated carbon supercapacitors and 3 times that of a comparable thin film lithium polymer battery off the top of my head, but I could be wrong. You can find the original paper at the AAAS (American Association for Advancement of Science) website, but its behind a registration wall, and they do mad data mining, so registering might take a while. Also, I have to remind you that this is an article on io9, not in the Scientific American. There are several other articles about this which likely came prior to io9 picking up on the story, and im pretty sure they provide some additional numbers which you so or so will find in the original paper on the subject. Here's the Kady paper that is referred to by the way. http://www.sciencemag.org/content/335/6074/1326.abstract

Excuse me? This from the linked article (and in the paper abstract):

"These micro-supercapacitors demonstrate a power density of ~200 W cm−3, which is among the highest values achieved for any supercapacitor."

Granted its not a legitimate energy density (wrong units) but lets guess it is 200 Ws per cubic centimeter. I make that guess based on the comment in the video that they ran an LED for 5 minutes. So an LED is like 15mA and with a forward drop of a couple of volts so 30 mW. For 5 minutes your looking at 9000 mW-seconds, or 9 Ws for the small capacitor they showed in their video which could have been about a cm ^ 2. So if the cell they had made was 1/2 mm thick then a stack of 20 of them would be 1 cm^3 and 180 W-seconds (in the ball park of the abstract). There is a fun presentation on Supercaps [1] that was given to DoE in 2011. This computation does suggest that 200 Ws for this material would be a decent jump in capacity.

That said, I immediately dug an old LightScribe CD recorder out of my junk bin to start playing around with making graphene sheets :-)

[1] http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_revi...

>That said, I immediately dug an old LightScribe CD recorder out of my junk bin to start playing around with making graphene sheets :-)

You serious? Sounds interesting, do tell us more.

Of course I am serious! Still trying to figure out what they used as a 'base' graphite oxide slurry (pencil lead in solution it isn't)

That's still power density. Power is Watts. Total energy is joules. You haven't addressed the parent's concern. We are interested in how long it can keep up that wattage, ie. joules/sec.

I really don't want to come across as nit picky but is this one time when changing a linkbait headline to something more descriptive would help - on the iPhone this page did not render thE actual text for a full half hour (subjective) and I spent all that time with my brain whirring but not in gear - it was a little frustrating

A headline like "DVD Graphene sheets store charge super fast in lab" would have helped me shift the various articles into my own working memory whilst the page loaded.

Downvote with comments please

(And I seem to get the general idea that Graphene will be big, but this is unlikely to be the killer app)

This is the first time I've seen this argument against linkbait headlines, and I happen to like it a lot. I've never actually considered headlines from a psychological perspective.

I agree with you, the title could have been a little more descriptive. I have seen the same video posted here and on Reddit multiple times in the past few months. Although I don't mind it being posted again, since there is always a group of people who haven't seen it, a descriptive title could have prevented me from getting overly interested about this.

Am I the only one to think "hey, I could try this at home?" 1) prepare carbon slurry 2) pour on dvd 3) etch with LightScribe DVD drive... 4) Peel of graphene layer ...?

I wonder what, exactly, goes into the carbon slurry and if it's necessary to etch a particular pattern with the LightScribe.

I'm right there with you. I've been looking around to see more details on the process. Besides getting ahold of the materials, i think the most difficult part would be taking a graphene sheet and actually making it a supercapacitor. I think it requires layering it between some sort of electrolyte sheets right?

Yes, sounds right. Quoting from the paper cited above "Thus, a device can be readily made by sandwiching an ion porous separator [Celgard 3501 (Celgard, Charlotte, NC)] between two identical LSG electrodes."

But the gel seperator they used was the standard industrial seperator gel for sCaps...there was a video on this, but it's too late tonight, i'll look for it tomorrow.

The supercapacitor they created is planar, you don't need to layer multiple sheets, you just need to print it then deposit the gel-like electrolyte and put it together with some copper tape and klapton tape. It's written/explained in their paper: http://www.sciencemag.org/content/335/6074/1326.abstract

I thought so too but the result would be a CD with grey stuff on it.

My plan is to sell Lightscribe DVD drives and graphite oxide, like the store that sold shovels to gold miners.

I wondered about the etching process too. It might not be at all like a normal R/W pattern for a DVD. They could conceivably be scanning radially, or using a very slow revolution, or (is this possible?) re-tuning the beam's frequency. Not insurmountable, but might require low-level re-writing of the driver, depending.

or just rig your own device and grab the high powered laser off of a blue ray player and slowly pull it to the outer edge. Seems a whole lot easier than having to deal with it messing up a drive within a computer.

>(is this possible?) re-tuning the beam's frequency.

No. DVD burners simply use a 630nm or 650nm red laser diode. It can not be re-tuned more than a few nm, by regulating the temperature of the diode.

You could replace the diode, but that is more effort than it's worth, and there's not much else to replace it with. If you wanted more power you might use a different diode, but the diodes are almost always buried really far in there and you would have to replace the electronics as well.

After reading several papers on this I think that the hardest issue would depositing the GO and electrolytic layers on a CD substrate. Although there are some fairly reliable and not terribly difficult methods I doubt many would have the materials at home. I would love to try this but I'm a poor student. I may see if I can locate some GO onthe chem labs this summer when no ones around.

It's graphene, especially tiny bits of it, a bit of a biohazard also? (Think asbestos)

I've never heard of any health risks. People seem to handle graphite pencils ok (OTOH, coal dust isn't exactly the best thing in the world for you, but it is hardly asbestos)

Their paper [1] show that it is actually quite simple, glue a PET layer to the CD, then deposit graphite oxide solution and let it dry overnight, to then put it in the lightscribe drive. They also explain how the supercapacitor is built with the electrolyte and how to make the electrolyte yourself, the hardest part from what I've read is actually getting graphite oxide.

[1] http://www.sciencemag.org/content/335/6074/1326.abstract

The professors who found this actually wrote a paper [1] explaining every step that they did to create their supercapacitor, including the formula for the gel-like electrolyte they used. The biggest problem I've found to making this at home is getting graphite oxide. They are expensive on the net (google it, not linking any store because I don't know any trustworthy), or hard to make (the usual method requires strong oxiders like sulfuric acid) [2]. There is a bottom-up approach to making them, that uses glucose [3], but I have no idea how hard it is, I need help from someone more knowledgeable in Chemistry before I try it. So if you want to really try this out, read those papers.

[1] http://www.sciencemag.org/content/335/6074/1326.abstract [2] https://en.wikipedia.org/wiki/Graphene_oxide [3] http://pubs.rsc.org/en/Content/ArticleLanding/2012/JM/c2jm15...

You don't even need the DVD burner - you can use sticky tape[1] (to make graphene anyway). That is actually how it was discovered[2], and that was worth a Nobel prize.

[1] http://www.scientificamerican.com/slideshow.cfm?id=diy-graph...

[2] http://www.independent.co.uk/news/science/the-graphene-story...

You have no control of the layer thickness through this process, and their supercapacitor design actually uses the graphite oxide that isn't turned into graphite as an insulator between the graphene sheets (their supercapacitor is planar, it does not use multiple layers). So no, while you can get graphene from a pencil and sticky tape, that's useless for this application.

I don't know much about the technology of this, but I used to play with capacitors during my teenage years and if this works even half as advertised it would be truly life altering. We could have "hybrid" solutions of a capacitor combined with a battery with the capacitor acting as a buffer to improve battery life.

Agreed, I was thinking that hybrid solutions do seem likely.

Hybrid solutions are hypothetically very nice, but as I understand it in reality the large battery banks associated with a gas-tank-like range, and the relatively minor amount of power the motors can actually put out, means that short-term power density isn't actually much of a problem.

Using Graphene to build supercapacitors is not a new idea as this video suggests. Here is an article from 2.5 years ago in PhysicsWorld describing another team doing almost the same thing:

http://physicsworld.com/cws/article/news/2010/nov/26/graphen...

I'm not a scientist. I can't not say anything how this could be a revolution but if you want learn the basics about Graphene. Start with this video on youtube: http://www.youtube.com/watch?v=EX8ClPVkD1g and then to this http://www.youtube.com/watch?v=SXmVnHgwOZs or just search it on youtube. This helps me a lot to understand. Have fun.

Nice videos. Thank you sir.

Well, the graphene seems easy enough to manufacture. What are the obstacles to start using this technology right now? What is still missing?

Experience. At least let people experiment a little bit more before building huge fabs using technique A only to realise that technique B works at half the cost and twice the time-efficiency.

But isn't there are huge market advantage to using the technology now, before your competitors do. If you wait until technique B, then you loose out on the first (or early) adopter benefits, and probably lost customers to your competitors that implemented the technology before you.

I suspect that the reason we are not seeing this technology in practice yet, is because of how long the design cycles take. I am not familar at all with small device manufacturing, but it seems like it would take a lot of iterations to make everything fit together so tightly, and a year may not be enough time to introduce a different battery system. Especially a battery system that your engineers have no experience with.

Having said that, batteries do seem like a pretty stand-alone component of phones, so it may be possible to design a graphine based battery that replace an existing phone battery without modification to the phone. It might involve doing more work in the battery to emulate properties of the traditional battery that the phones were designed to compensate for, but it seems like there is enough room in a battery to do that.

The other problem I can see is that standard phones would likely be incapable of charging these batteries at full speed, which would only mean the batteries need a charger external to the phone.

Again, not as good compared to designing the phones with these batteries in mind, but still useful.

The main problem I can see with pursuing these batteries is that by the time you are ready to sell them, there may not be a long enough window before they become standard for it to be worth your while.

Makers of portable phone rechargers may be the compromise to those issues.

Regardless, excluding unforeseen drawbacks to this technology, I suspect we will be seeing it within 1 or 2 generations of phone.

> But isn't there are huge market advantage to using the technology now, before your competitors do. If you wait until technique B, then you loose out on the first (or early) adopter benefits, and probably lost customers to your competitors that implemented the technology before you.

I am pretty sure every half-decent company has a research team on graphene right now, it is just that they don’t have results yet because results take time and making sure that these results are correct takes even more time.

Furthermore, as you said – even if we now managed to build a battery that charges in half a minute, the surrounding infrastructure is not yet there, and especially with components as critical as batteries, you don’t want them to break/blow up at your customer’s place.

In my inexpert knowledge I can see a few problems, while they have probably seen potential, they have yet to prove it can scale. Then there is getting manufacturers of devices to buy in to super capacitors and even worse getting battery life obsessed consumers to accept 1/4 the life as current Li Ion batteries is better because it has nearly instantaneous recharge times.

Maybe you can have both a Li Ion and one of these, and you only sue the LiIon after the graphene one is depleted. That way, you can recharge quickly to a fraction of total power, and optionally wait longer for a full charge.

Maybe but both are going to take up space and the video isn't really clear on how much space the super-capacitor is going to need so you'll probably end up with the same problem of not having the same long life as just having the single slower charging Li Ion battery.

In my experience, the reason people are obssessed with battery life is that when it runs out (which it does), then you are pretty much screwed until you can plug it in for the night.

I think that vendors could easily sell devices with a smaller capacity if they can charge in seconds. This seems like a benefit that is very clear, easy to explain, and understandable to a typical consumer, and it provides a near perfect solution to one of the major inconveniences of current phones. And, that inconvenience happens to be what people currently look to long battery life to mitigate.

Perhaps, I know I'd rather have a super fast charging phone that lasted a day than one that lasted 3 days and takes a long time to charge, but there are still people out there that seem to think the megapixels are the only thing that's important in a camera.

I think the vendors could already charge the batteries faster. A Tesla supercharger charges 40/85kWh in LiIon battery capacity in 30 minutes (from empty, it gets harder to push charge in as they get full). They use off the shelf batteries.

But the dirty little secret is of course that it's not necessary. You need one day of battery life, then people get home and charge it by their nightstand. Similar with the Tesla, it has enough range to get through five times the average American commute, and the majority of people just charge at home when they sleep.

Bandaging peoples irrational fears might simply not be a very viable business model.

The high current needed for fast charging requires thick connector wires and produces a lot of heat in the battery, and also in other components of the power circuitry. The heat is the limiting factor in the charging speed for phones.

> Bandaging peoples irrational fears might simply not be a very viable business model.

Are you kidding? It's one of the best business models ever.

In this case I think you have it backwards. Instant charging isn't bandaging a fear, because you rightly make the point that the fear of running out of power is already covered by ensuring the device has sufficient capacity for the worst case. Indeed it will create a new fear: forgetting or not being in a position to top off the charge when necessary.

I don't believe there is anything "missing" to prevent it from starting up. It simply takes work, time, and money to get it off the ground.

I can see this tech being widely used in place of current capacitor technology in a shortish timeframe- maybe 2 to 4 years. It'll also be used in novel technologies as battery replacements, especially for high discharge rate applications, within a similar time scale.

There's a lot of work to make sure this is actually a safe thing to use. I know lithium ion batteries are pretty dangerous, but you need to be damn sure this is as safe or safer. How does it hold up to heat, cold, punctures, short circuits, etc? What about degradation over time?

Also, there's a lot engineering that needs to happen about how to integrate the proper charging circuits. Plus all the work that needs to go into actual mass manufacturing.

In all there's a shit ton of work for any product to actually make it to a mass market.

Electrons don't like graphene, its like trying to stick electrons onto a hunk of wood - which also has a large capacitance. The real story isn't that graphene has magical properties, its that graphene can be tuned and engineered.

I'd love to see this technology being incorporated into Tesla's batteries. With super-fast and long lasting charges their cars might become viable in countries where charging stations are either incredibly rare or nonexistent.

Countries with poor infrastructure and handy sources of insanely high wattage power who can afford $50,000 sedans? Which countries would those be?

I'd hardly equate lack of abundant electric car chargers with poor infrastructure. The example I was thinking of is the UK where I live, where electric cars aren't as common as in SF or the east coast.

note, I didn't downvote your comment.

Fair enough but the basic point stands - a fast charging facility would be harder to set up than a Tesla "supercharger" (it would, in essence, need to use capacitors to provide the necessary power and would be limited by its available power.

Why specifically tesla and not just electric cars in general?

I searched a little, but the information is confusing. The superchargers (apparently) use 90kW/480V=~190A. I want to highlight this: 190A!!!

A usual home connection can handle only up to ~10A, so 190A is a lot of current. To handle this you must use very thick wires. To charge faster you need move voltage or handle more current, probably you will need even thicker wires and to be careful with the safety measures.

Additionally, this experiment use only in a tiny lab sample. To increase the size and make a big model for a car, a lot of technical details will appear, for example how to handle all the heat that the battery produces during the charge / discharge cycles.

A typical new house in the US is wired for a 200A 240V circuit, or about 48kW.

By contrast the energy flux of a garden-variety gas pump is in the tens of megawatts.

Is that at the fuse box or the power point on the wall? Sorry if this is a silly question, it's just that here in NZ it's nowhere near that at the wall as the fuses are 10 amp ish.

The 200A are at the fuse box (in new houses, old houses may have less).

The wall sockets usually have 110V-15/20A connections. But there are some especial sockets with 240V-30/50A for special applications, like clothes dryers and electric ovens.

In our old house some genius used paper clips instead of fused wire in the (very old) fuse box. Not sure how I didn't die when I draped and extension lead in a puddle and got a shock. After I recovered I looked in the fuse box to see why the fuse didn't blow and found one fat paper clip over the gap. I'm not sure what current the box took, but I'm sure glad it wasn't 200Amps.

Seems pretty simple to me: You create a grid for your house, so it will always have electricity. You trickle charge a rack of graphine Supercaps for your house using mains. You dont need to send that power all at once.

The standard devices to handle passing from mains to battery should be able to be used.

I think there's little issue with heat, as a major advantage of capacitors is efficiency in charging and discharging.

I wrote this last time too: 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.

Hi - 1st post on Haker news. Please be nice :)

Aren't debates over energy density of super conductors v. Li-Ion batteries missing the important point, relative cost?

E.g. If the energy density is 1/4 lower but the cost is 1/40th as much then electric cars get ALOT more viable. Can anyone guess at the relative cost?

How important that point is depends on how much range affects viability as opposed to the cost of the vehicle itself. Electric cars are rather expensive I guess, but few people are going to make the switch to cheaper cars if they only have a range of 20km.

(semi-serious) Title should be “Meet another scientific accident that could change the world”

I don't quite understand the maths behind all this but it certainly sound positive overall. It normally takes a while for things to get to the consumer but how long do we think it'll take to get to us or cars? Will it even get to consumers?

Diamonds are carbon based but you can't use them to grow vegetables.

Not with that attitude, just put them in a 100% oxygen environment and heat with an arc furnace and Bob's your uncle you got CO2.

Anyone else remember when this was posted a few months ago? (I wish my account was named pepperidge farm, just for occasions like this.)

This comment feels like its one step away from just being the word "repost". I really like browsing reddit but please leave these types of comments there. Hacker News is not reddit.

Yeah, I don't understand the down votes honestly. We've seen this - not just a few months ago.

Why is it ok to post again? Should I have provided the HN link?

It's more that your comment didn't add anything to the conversation.

If you'd said "You can find the previous conversation at XXX" then you'd be contributing. As it is you just added noise.

Thanks for elaborating for me. The key point is adding to the conversation. Novelty accounts tend to be the realm of Reddit but one of my favorites is the one that says "Anyone looking for more information..." and goes on to list past posts of a link. That's infinitely better than simply "Repost"

Reply on news.ycombinator.com