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EEStor Issued a Patent For Its Supercapacitor
An anonymous reader sends us to GM-volt.com, an electric vehicle enthusiast blog, for the news that last week EEStor was granted a US patent for their electric-energy storage unit, of which no one outside the company (no one who is talking, anyway) has seen so much as a working prototype. We've discussed the company on a number of occasions. The patent (PDF) is a highly information-rich document that offers remarkable insight into the device. EEStor notes "the present invention provides a unique lightweight electric-energy storage unit that has the capability to store ultrahigh amounts of energy." "The core ingredient is an aluminum coated barium titanate powder immersed in a polyethylene terephthalate plastic matrix. The EESU is composed of 31,353 of these components arranged in parallel. It is said to have a total capacitance of 30.693 F and can hold 52.220 kWh of energy. The device is said to have a weight of 281.56 pound including the box and all hardware. Unlike lithium-ion cells, the technology is said not to degrade with cycling and thus has a functionally unlimited lifetime. It is mentioned the device cannot explode when being charge or impacted and is thus safe for vehicles."
How do you figure?
The patent specifically mentions kW*H in reference to the 52.220 number.
I assume you were just trying to be smart and correct the summary thinking it was a typo. However, a kW*H is a valid unit of measurement.
In fact you could use them interchangably but it would give the very wrong idea as they measure different things.
A watt is one joule of energy flow over a second. so a KW would be 1000 joules of energy flow over 1 second.
A KW*H is a flow of a kilowatt continuously over an hour, therefore it would be a flow of 1000 joules over 3600 seconds.
So to recap:
1 kw = 1000 joules/sec
1 kw*h = 1000 joules/sec * 3600 seconds
If you were just going to measure the total energy usage, you'd have to keep it just in joules, in which case 52.220 KWH would be 187,992,000.
So yeah, big difference caused by little changes in notation. Of course i haven't done electricity in ages so i probably oversimplified somewhere and fubar'd up.
You never realize how much manually made unmanaged "linked" lists suck, till you have src.link.link.link.link...
A lot of cool data in the patent filing.
3-6 minutes charge time for 52 kWh. 286 lbs for that compared to 752 for a Li-Ion battery. And the Li-Ion takes 6h to charge.
No one has noted yet that these caps also have insane *individual* unit specs! They're rated for 3500 V, have about 1 milli Farad and weight about *5 grams* each. This is absolutely unheard of. Normally you have to choose two from: small size, high voltage and high capacitance.
The energy that a cap contains is written as E = U^2*C, so it's obvious that scaling up the voltage gives you high rewards very rapidly. The problem has been that the insulating layers inside caps cannot handle high voltages without being made very thick. This means less capacitance since ideally the plates should be as large as possible and as close as possible.
The bill of materials looks nice too: Aluminum, Barium, Titanium, simple plastic. If they can actually produce the goods, this could be very cheap to mass produce.
If they can commercialise this, it *will* revolutionarise portable power (3500 V inside your iPod?;). But until they show a working prototype I'd hold my horses and not bet on this to solve our energy storage problems.
It's NOT KW*H! It isn't kw either, nor is it kw*h.
It is however kWh, meaning kilowatt hour, and it is a unit of energy.
Start getting you units right, and capitalization DOES matter. M = mega, m = milli.
Um, not really.
A combustion event, aka 'explosion' occurs at the beginning of every power stroke in a reciprocating internal combustion engine. When an engine 'knocks' there is a combustion event as well. What makes it a 'knock' instead of a normal part of the power cycle is that it occurs at the wrong time. Knocking indicates perhaps a spark timing issue or the use of a fuel with an improper octane rating (which indicates resistance to knock). Octane ratings describe the resistance of the fuel to spontaneous ignition relative to a mixture of iso-octane (by definition Octane rating of 100) and n-heptane (by definition an octane rating of 0). Extrapolation is what allows for an octane rating of greater than 100. Diesel fuel has a similar concept, a Cetane number which indicates susceptibility to "spontaneous" combustion, since diesels use compression to ignite combustion events rather than an electrical spark.
Modern cars do depend on a much higher octane rating than historical vehicles. This allows for running on a much higher compression ratio and/or the use of turbo-chargers which allow for an engine that is thermodynamically more efficient (as compression ratio approaches infinity, thermodynamic efficiency approaches unity). This is one reason why diesels (compression ratios in the 20's rather than 5-10 for gasoline vehicles) get better mileage for a comparable vehicle/power output.
You are, however, entirely correct about the relative difficulty of causing a gasoline burn or explode. Only the vapor state is flammable and only at a narrow range of particle size.
According to the great wiki god, ic engines average 18-20% efficiency, and peak at 37%; so a tank is between 100..210 kWh usable. Presuming the 18% is around city, and the more direct applicability of regenerative braking, the difference shrinks considerably.
If we really want to split hairs, we should note that "explode" and "detonate" are two different concepts. Some explosions are detonations, and others are simple deflagration where the fuel burns rapidly but evenly over some period of time.
The physics of the two is vastly different. A detonation denotes an event where the material burns at a rate that is supersonic, and a deflagration is subsonic.
In a detonation, an instantaneous pressure jump moves through the material faster than the material's normal speed of sound. This produces instantaneous pressures that can go into the millions of PSI. A strong enough shock will shatter any material.
Occasionally, the fuel/air mixture in an automobile cylinder will partially detonate. These cause weak shocks that we notice as "knocks" and "pings" - and which over time will destroy the pistons in the engine. High compression, low octane fuel, and local hotspots in the cylinders are the usual reason for this.
As a side note, even smokeless gunpowder doesn't detonate, it just deflagrates on a time scale of 0.5 - 3 milliseconds. If it did detonate, the gun would quite spectacularly imitate a fragmentation grenade.
From the perspective of an observer outside the combustion both can produce similar effects, though detonations are much more spectacular.