[EDIT: EEStor have been unable to produce the hoped-for results as of 2018. This article is still correct, but I wouldn't get your hopes up about EEStor at this point. To be fair, they're still around, and apparently still trying... but after all these years it seems very unlikely they will actually succeed.]

EEstor, of Cedar Park, Texas, is either headed for an ignominious (though well intentioned, I think) fall, or they’re in on the ground floor of the Next Big Thing. You see, EEstor is trying to produce a material that will in turn make relatively high voltage ultracapacitors practical.

That’s a mouthful, but it isn’t really that hard to understand; and when you understand it, the potential for change is mind-blowing.

An ultracapacitor is just a capacitor with a lot of capacitance. And a capacitor itself is just a device that stores electric charge. But it doesn’t do it like a battery does. Batteries store charge in chemical form, and there are several unfortunate consequences of that. They discharge slowly; they charge slowly; and if you get too near the limits at which they can accept or deliver charge, energy is wasted as heat. Batteries don’t like extreme cold or extreme heat. On top of this, even a well-treated battery has a limited number of charge / discharge cycles. That’s why you have to replace the battery in your car every few years. They just… wear out.

Ultracapacitors, on the other hand, store energy as a surplus of electrons in one conductive region, and a deficit of electrons in another, separated by a very thin insulating barrier. They can accept charging current at amazing rates, without any waste heat; rates that make batteries look positively stone-age. More than that, they can discharge just as fast, and again, without any waste heat. It doesn’t wear them out, either; fast, moderate, slow, it’s all the same to them. Nor do they care how many times this goes on — they have usable lifespans that could be hundreds or even thousands of times the life of a battery, even under the very worst circumstances. They even work to specification over considerably wider temperature ranges. The higher the voltage the ultracap can handle, and the more capacity (measured in “farads”) it is rated for, the greater the total energy it can provide on discharge.

Another benefit is that with a properly designed home charging station, which would also use ultracaps, you’d be able to “fill up” your vehicle at home — in just a few seconds. Now, your home’s electrical service actually doesn’t have the capacity to pull that off, so the way it works is the charging station charges all the time at a moderate rate, all the time storing energy to be used when you want to “fill up.” Once you fill up, the charging station begins to refill again, and within a day or so, it’s ready to refill you again. The economics of having a fast charge station like that at home have yet to be determined, but technically speaking, it is perfectly practical to do.

What a vehicle! Charge it up in seconds, let it “trickle” charge itself while sitting out in the sun… if you didn’t drive but a short distance to the grocery store now and then, an exceptionally efficient vehicle would never need to be plugged in at all. With nothing but a small solar panel, vehicles parked for the winter would be fully charged and ready to go come spring. No more dead batteries, no more jump starts, no more weak batteries in the cold, no more buying a battery every few years, no more gas stations… Wow. Just wow.

So why are we still using batteries? Simple: Ultracaps can’t store as much energy as a battery can in the same amount of space or weight. The key issue is that — thus far — they aren’t very high voltage when they offer high capacity in farads. And it’s the voltage that really helps them store energy: For you math heads, the voltage term is squared; the capacity isn’t. The bottom line is that you can’t just replace your battery in the same space or at the same weight.


That’s where EEstor comes in. They’re working on a material that they have said will allow ultracaps to store energy at much higher voltages, while retaining the ability to provide a very high capacity rating in farads. The science is good; they’ve got two patents, both patents have been examined, and the technical people you’d want to hear from have all chimed in and said, yes, this material, in the specified configuration (which is essentially defined by the phrase “ultra-pure”), can be used in this application.

Looking at EEstor’s patents (#7033406 in particular – the other is #7466536)) and taking them at their word, two numbers jump out: 3500 volts, and 31 farads. Doing the math, the maximum energy in joules that can be stored in a device with those specifications is calculated using the formula at the right this way: 3500v squared (which is 12,250,000) times 31f, which is 379,750,000, divided by two, which is 189,875,000 joules. Now, a gallon of gasoline can provide about 130,000,000 joules of energy; so, presuming 100% efficiency for both energy sources, the claimed device provides the equivalent energy of about 1.46 gallons of gas.

In fact, typical electric motors reach about 90% conversion efficiency, and gasoline conversion efficiencies in a modern car run about 25%. This imbalance changes the numbers quite a bit; that provides a multiplier of about 3.6 for the electric system, bringing the power delivered to the car by the EEstor unit up to the energy equivalent of about 5.2 gallons of gasoline.

A reasonably well designed modern car can achieve 35 miles per gallon in range, and as we’ve already compensated for conversion efficiencies to compare the EEstor unit to gasoline, we can use the 5.2 gallon figure to estimate a range, based on the presumption of a similar chassis; that range would be 35 times 5.2, for a range of about 182 miles. Not great, but not too bad, either. Two of EEstor’s units would give you about a 360 mile range, which is right on par with a vehicle that carries a ten gallon tank of gas at 35 MPG.

Looking further in the patent, the claim is also made that the device weighs 336 pounds. A gallon of gas weighs about six pounds, so the energy equivalent of the EEstor device in gasoline weighs about 31.2 pounds. So gasoline provides about 10.7 times more energy per pound than the EEstor device, based on the published claims and on realistic energy utilization from both sources, and presuming no energy recovery from things like deceleration. Two units would be 672 pounds.

Another interesting way to look at the device is to consider that a small car generally has about a ten gallon gas tank, so when full, it is carrying about 60 pounds of gasoline. The EEstor unit weighs about 270 pounds more than that, so you can think of it as a large passenger — like carrying a football linebacker around in addition to a full tank of gas. Nothing a modern car couldn’t do without any particular stress. But there’s another factor here, and that is the weight of the gasoline engine and transmission; electric motors are far lighter than gasoline engines, and they don’t require transmissions, either. I really can’t give you hard numbers here, because engines and transmissions really do have widely varying weights, but rest assured that it makes the idea of carrying 672 pounds of capacitors not that big a deal after all.

Such a device, even in the first generation, would provide those fast charge and discharge capabilities, temperature range, minimal energy loss due to use, and long, long life. The obvious technology to benefit as I have just discussed is electric vehicles; they’ve been limited by batteries since they were first conceived, and EEstor’s invention would enable the relatively easy creation of electric vehicles with decent range, higher power, zero pollution, ultrafast “fill” times, the ability to recapture energy when decelerating and/or going downhill, and even when parked (via solar panels.) And… we need electric vehicles.

But that’s not all. Un-interruptible power supplies (UPS’s) use batteries to supply power when the power from the wall socket goes away, or drops too low for safe operation of the devices connected to the UPS. You may be familiar with these; many computers are attached to one. But there are many other uses for them. For instance, I have one on my home theater projector because if the power fails to it while it is running, the fan stops immediately — and if the fan stops before the bulb is cooled off, the bulb life is substantially reduced. And bulbs for these projectors are more expensive than the UPS is!

Some UPS’s even make power from the batteries 100% of the time, and all the connection to the wall socket does is run a charger that makes sure the batteries are charged and the UPS is always making AC for the connected devices. These are good UPS systems because there is no “switching” time; they don’t have to switch from “wall ac” to “backup ac” because they are always supplying “backup ac.”

So UPS systems are extremely useful. The problem with UPS systems is, in a word, batteries. They have to be replaced at regular intervals, because they simply don’t have an operating lifespan that is very long. Now imagine UPS systems that use ultracaps instead; no maintainance. None. No, they’d just work. For decades. Perhaps centuries. And they could be made quite large. Also, a UPS system that uses batteries can’t be used again for a long time after it has run because the batteries are discharged. It will take many hours to re-charge them. Compare that to an ultracap based UPS, which can recharge in just seconds and be fully ready to go.

Wouldn’t it be nice to run your entire home off a UPS? Then, when the power company has a hiccup, or lightning damages power lines, you wouldn’t even notice. Your fully-charged UPS system, which might have been sitting quietly in your basement, unused, for five years, without a single thought from you… instantly takes over and you don’t even know there is a power outage, except if you see your neighbor waving a flashlight around in their window…

Sound crazy? Not at all. Here’s an interesting factoid for you: Vehicles take far more energy to run than your home does. The average home here in the US has a maximum 12,000 watt electrical supply (100 amperes at 120 volts is 12 kw) of which you probably rarely use more than three or four thousand watts. A vehicle can require far more than that during hard acceleration or when working against wind resistance at high speeds. The Tesla Roadster, by Tesla Motors, can draw 185,000 watts (not a typo!) from its on-board electrical power system. So as it turns out, any power plant that could run a sporty or heavy duty electric vehicle could run your home very easily, with the right conversion electronics attached (which, to be fair, would be different from those needed for the vehicle.) Where do I sign up?

The same thing applies for small scale power systems that get energy from solar, wind, water and so forth. Today, they pretty much have to use batteries for interim storage, and that means regular replacement of an item that is physically heavy, expensive — and toxic. Not only that, but when it isn’t quite ready to be replaced, it doesn’t work quite as well as it used to, either.

Enter the ultracap: Now these power systems become maintainance free as far as the power storage goes; wind generators need attention, and even solar panels get twitchy after three decades or so, but that’s still quite a bit better than having to replace your batteries every few years, and dealing with reduced storage capacity in the last year or so.

Something else that should interest you is that even if the power generation that makes the electricity for these vehicles and other systems is based on petroleum, the power company’s generators are more than twice as efficient at creating power from petroleum products as compared to your gas or diesel vehicle is (your car might reach 25%; a gas/steam turbine power station can hit 58%), so although in the immediate sense, it is true that we’re moving the consumption of said products to the power companies, in the process we’ll consume a lot less of them. This also sets up the infrastructure properly so that non-polluting plants like nuclear, solar, hydro, wind, tidal and geothermal can smoothly replace the petroleum burning plants. Since you’re already running on electricity, you won’t even notice. But the environment will.

Sounds great, doesn’t it? So what’s the catch? There has to be a catch, right?

Here it is: No one in the ultracapacitor business — except EEstor themselves — thinks they can make the pure material in question at the permittivity (this is the key value that will allow high capacitance in a thin film) they claim to have achieved in their patent. And if it doesn’t reach that value, the ultracapacitors they plan to make will underperform the company’s predictions. At about 50% of the predicted permittivity value, they’ll begin to underperform batteries, too.

On the brighter side, no one thought they could make their material at the purity they needed to either, but probably much to the annoyance of others in the ultracapacitor industry, they have announced that goal has already been met. EEstor is still working on the material, and as industrial processes go, they’re not too far behind the original schedule. They’re claiming they’ll be ready to deliver this year, in 2008. (Note… it’s now 2009, and still no results. Now they say late 2009.)

Update, April 22nd, 2009: EEStor claims they have had certified a permittivity of 22,500 by Dr. Edward G. Golla, PhD., of Texas Research International. This is more good news, and as far as I know, leaves only mechanical and assembly issues remaining to be resolved.

Update, May 21st, 2009: Zenn confirms EEstor’s certified permittivity of 22,500. This opens the door for more investment by Zenn and should both silence the nay-sayers and leave a clear road to the final product.

Zenn, a Canadian company that makes electric cars, has invested in EEStor, as have Lockheed-Martin and a few other organizations here in the US. Zenn has obtained the right to make the first electric cars using the new ultracapacitor units. But EEstor is a private company, and they’re making the most of that by not letting anyone outside their private investors know what progress, if any, is being made towards actual industrial production — the most anyone gets out of them is a terse “in 2008.” (Now, again, 2009.)

Which makes watching them, in my estimation, very entertaining. They could just “never get there”, because what they’re trying to do is very, very difficult, or they could literally be the pivot about which the entire transport industry and many energy storage related technologies turns. Should they come through, I can’t imagine how any medium to large capacity battery company could survive. Small batteries, probably yes.

The reason small batteries will still be needed, at least for a while, is that the trick to storing large amounts of energy in a capacitor is high voltage; that is far more important than having a high rating in farads. But small devices tend to run on low voltages, which means an ultracap needs voltage conversion electronics that are, at least for cheap portables, not really cost effective. At least at the moment. Vehicles need voltage conversion as well, but there’s an economy of scale there in that a vehicle design would carry a lot of ultracapacitors, and so the conversion electronics wouldn’t represent a prohibitive portion of the entire cost. So I think we’ll see small scale lithium batteries having a market even if EEstor hits the target squarely. No ultracaps for your iPod. Yet.

The reasons that ultracaps need additional electronics are twofold. First of all, in high-power applications (like a vehicle), the voltage being maintained will be quite high, hundreds or perhaps even thousands of volts. But your average motor runs on under 100 volts, so conversion electronics are required to bring the ultracap supply down into the range where it is compatible with the motor. Secondly, batteries tend to stay near their “normal” voltage until they’re quite weak; ultracaps (and capacitors in general) don’t do this. They smoothly drop in voltage as you withdraw energy from them. So electronics are needed to convert that changing voltage into a steady one that is convenient and appropriate for the system they’re supplying power to.

This characteristic might appear to be a disadvantage, but there are advantages to be had as well; because the ultracap’s output voltage at any one time is directly related to the amount of charge remaining in it, you can actually determine, reliably, how much energy (which translates into range and speed for a vehicle) remains. Batteries don’t work like that. Even an almost dead battery will show the normal voltage… until you try to actually use the thing.

Another benefit is that this means that the electronics in your vehicle — GPS, CD/MP3/DVD player, the car’s trip computer, etc. — will all have access to a very stable, dependable power supply. Again, batteries don’t work like that. When a modern car is charging its batteries, you might have 14 or 15 volts applied to your electroncs; when the car is starting, they might see only eight or so. Within an electronically regulated ultracap system, they’d see 12.6 volts all the time, which is the voltage they’re designed for. This will not only make them more reliable, it’ll make them last longer and behave more consistently.

What I suggest is as you travel about the net, consider keeping your eyes open for what EEstor is up to for the next couple of years. I’ve set myself up a “Google Alert”, which emails me every time Google finds some tidbit on the net that mentions EEstor. In fact, they’ll probably mail me my own blog entry tomorrow, which will be amusing, I suppose.

If EEstor were a public company, I’d invest in them. Not because I’m certain they’re going to succeed, but because as long shots go, success means the game will change all around us, and in amazingly good ways that we actually need. In the meantime, the day they show working units that meet specifications, I plan to short some battery stocks. No pun intended.

Good luck, EEstor; I’m rooting for you!