Friday, March 6, 2009

EEStor Posting of Interest

I grabbed this posting from the blog in the link and it is an excellent effort at describing what is going on with the EEstor protocol. It polishes my understanding of the technology and I certainly concur that the claims been made are difficult to achieve benchmarks. And yes, we all want to see this succeed.

Personally, I would like to see a working device make in some way with the specific particle sizes just to see the electro magnetic characteristics test out. How about painting some of it on a conductor? This may be simply naïve, but tricks like that go a long way to making folks comfortable.

I did exactly that once with another product surrounded by even wilder claims that landed on my desk. I designed a simple experiment that showed the claimed behavior and demonstrated it to myself. That simple do it your self experiment eliminated all further objections and the project progressed.

This sucker needs just that.

All very interesting ... non-batteries that achieve energy densities on par with the current chemical practical record holder, Li::MnO (generally known as "Lithium") cells. The common garden variety AA LiMnO cell (rechargable) delivers 3.6 volts, holds about 2 amp-hr of juice (thus stores about 7 watt-hours of energy) ... in an AA package of about 5 milliliters capacity. So ... let's see. 7 Wh x 1000/5 = 1.4 kWh per liter. Hey! Similar to the 1,500 kWh/liter of the "full production" EEStor BariumTitanate cell. Cool.

The only difference is, the BaTiO capacitors - even with 1/100th the size of the patent claims - have yet to be produced. EEStor is to date, a proverbial "announcement engine", sending updates and developments, and endless chitter-chatter to CEO's of every conceivable target market - then disingenuously claiming to be "working closely with (a list of 100) industries". Right.
I think the idea(s) are great (after all BASF, Motorola and a number of others filed for patents for their competing ultra-permitivity dielectrics) , but practically, the issue is that it is virtually impossible to create void (arc-conduit) free ultra permittivity dielectrics ... even filled ones. Layering (say depositing dozens of spin-coated micrometer

scale films) ... could utilize the statistical effect to decouple vertical voids between electrodes (which is why mica has such a spectacular dielectric strength) ... but in the end it may end up in a cat's game.

YET - and let me just say here that I AM a devotee of this technology - yet, there are three striking advantages of the capacitive approach - even it it "only" achieves energy/weight densities similar to the best chemical methods - that are compelling. (a) two orders-of-magnitude faster charge/discharge cycles. (b) near-100% charge/discharge efficiency. (3) practically infinite lifespan. There are also a trio of secondary - but clearly useful - aspects that gather little press... (4) common-ness of materials, (5) low-toxicity materials, (6) no temperature dependencies.

The best batteries (at charging) have endothermic dissolution chemistries that 'suck up thermal energy' as they're being charged. So, while the nature of solute-conductivity (over metal) generates a lot of ohmic heat from high charge rates, the heat is reabsorbed by the endothermic reaction, yielding quite moderate cell heat-up. Of course, it can be pushed (the endothermic reaction only absorbs heat relative to the reaction rate, but the heat goes up as the SQUARE of charging overvoltage) to generate heat ... to maximize charge rate. Typically today's cells are rated between 0.2C to 1.0C charge rate ... e.g. a 2.9 Ah AA cell can be charge maximally in around 2-3 hours (actually somewhat faster, as witnessed in the remote-controlled toy vehicle market).

But lets just say that 3 hours (10,000 sec) is nominal for batteries. They can be put in series-parallel, and still retain the 10,000 sec rating (assuming not too much heat builds up). In order to get 5 minute (300 sec) charging, clearly 1.5 orders of magnitude charge-rate improvement is needed. This ... they're not going to get, under any circumstance. The internal resistance, delta-V squared waste-heat, and so on ... precludes it. further, those losses are non-recoverable in power. All megajoules lost to heat never are recovered as power.

So capacitors have a huge advantage there. This is not to say they're perfect - especially the titanate peroskvites (which are piezoelectric among other things), but the're pretty damned good.

The patent's 30 farad, 3500 volt capacitor would charge at 3.3 volts per second per 100 charging amps. To charge it in the 5 minute (300 second) window, it would need a charge rate of 12 volts/sec ... which would require about 350 amps. Hence the apologetics for "cable heating". Well, thick cables aren't all that expensive, and I could see water-cooled cables in thick black rubber (suitably armored) looking just like the thick hoses on today's filling-station gasoline dispensers. Just about as flexible, tough, and trouble free. A set of interlocks would keep these instantly-lethal voltages from escaping the housings. Yep, 5 minute charge times. Doable.

The second factor (near 100% charge-discharge efficiency) is also critical. Conventional chemical batteries - even the big mature lead-acid ones - tend to lose from 25% to 65% of the energy 'invested' in them. Put in 10 kWh, and you might only get back out 6 kWh. I don't think that is very attractive. By comparison, put 10 kWh into a super-capacitor, and 9.9 kWh comes back out. The 0.1 kWh lost is to resistive and/or dielectric hysterisis losses. That is pretty compelling.

Third (3) practically infinite lifespan. The "other" vexing thing about chemical cells is their almost immediate degradation in capacity, which continues fairly linearly over their useful lives ... then rapidly accellerates at the "end". This is nominally through permanent 'side reactions' that inactivate the electropositive anode materials; modern cell chemistry includes sacrificial compounds to compete for the parasitic oxidation pathways, thus keeping the anode materials from degrading as fast. The 'end point' (rapid decay) though is inevitably realized when the sacrificial compounds run out - as there is only so much 'space' for them in the galvanic cell ... before they start to degrade capacity itself.

Not so theoretically with solid-state dielectrics ... not run completely at their arc-over point. (i.e. when charged conservatively, dielectrics have lifetimes approaching centuries, if not milennia). This is a remarkable boon, as it puts electrical energy storage on the same footing as hydrocarbon based fuel fluids. (A can of gasoline lasts ... the life of the can ... more or less). Yes, dielectrics still leak ... hence the figure-of-merit of 1.2% per year ... but that isn't at all impractical for all vehicular and most other moderate-term energy storage use.

Fourth (4) common-ness of materials ... titanium dioxide is one of the most common minerals (rutile, etc). Barium is a common component of sea water, and is widely deposited in the arid parts of the planet as Baryte... and is produced in the 'millions of tons' per year level presently. These characteristics, along with the other common components (aluminum, alumina, plastics, eutectic tertiary glasses) spell a future that shouldn't be clouded by a 'limited resource' issues. A demand for 300,000,000 300kg batteries a year requires 100 megatons of materials ... or about 10x our present baryte production to achieve. Sounds achievable to me.

Fifth (5) low-toxicity materials. Barium titaniate has a very low dissociation constant, meaning that it is soluble in acidic aqueous fluids in vanishingly small quantities. Barium IS toxic, and the soluble barium compounds are modestly toxic (on the order of lead compounds). But, barium SULFATE is so incredibly insoluble that the admission of even a small amount of sulfate as an antidote serves to entomb in-vivo the barium, rendering it harmless. Titaniates are also non toxic. They are so non-toxic, that the oxides, carbonates and sulfates of titanium are used presently in candy and confection manufacture. Sixth (6) no temperature dependencies. This is particularly important for practical vehicular use. Cars, trucks, earthmoving equipment and industrial equipment is supposed to work realistically from the arctic's temperatures to the Sahara's (-50C to +50C), reasonably reliably. The great majority of electrochemical cell chemistries and configurations suffer from electrolytes that "freeze" (or otherwise deactivate) below -10C. The problem is so severe that modern photographers cannot use their cameras below -10C for extended periods of time without protecting and heating the battery-packs. There is enough civilization living in lower-than-20-below temperatures all winter long that a very low operation point is a requirement. Likewise, many electrochemical batteries suffer from significant recharge-rate limitations at elevated temperatures ... since many of the chemistries utilize gaseous hydrogen in nanocrystalline carbon matrices for the cathodic material. At temperatures above +35C, the gaseous hydrogen rate-of-adherance to the carbon-matrix rapidly diminishes. Again, there are enough people who live in arid, high-heat areas, that this too needs addressing.

The BaTiO (and virtually all titanates) have operating ranges from -75C to +75C. This "solves" the problem of temperature dependency.

In any case, i didn't initially set out to write so much up. I am very much interested in seeing this technology actually produce some REAL WORLD, REAL-SCALE DEMO DEVICES. Not just endless talk about the dielectric strength permittance measurements, and 6 months between trials. This is getting to be TOO OLD of a story. let's just see impractical-but-notable megacapacitors being built. Show the world plenty of these, and in particular (since it is patent protected anyway), making nominal quantities of these available to hands-on-testing ... would be a great way for the researchers to "prove it to the world" and get excitement flowing.

For this is the problem with the technology that causes it to fail the GoatTech tests. No product, lots of talk - especially how it will save the world, solve the problems with every other new-tech/green-tech, endless microscopically 'incremental' developments (which sound like bullshit taken globally), and promises that tomorrow will deliver, but today way more funds are needed.

I just hate to give such a promising technology the title of "SNAKE OIL", but insofar as this old Missourian is concerned ... until they can show the world (and me) ... the oleagenous distillate of common asps ... it is.


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