1.3 - Ultracapacitors
1.3.1 - The Technology
Ultracapacitors (or ultra-capacitors, ultracaps) are extremely high energy density capacitors. Capacitors store electrical energy by physically separating positive and negative charges, in contrast to the chemical means a battery uses. Until 2007, the best capacitors could not store energy in amounts even close to comparable to a battery. This is changing fast, and now we are beginning to see ultracapacitors nearing battery capacities. A company called EEStor has announced that they are on track to exceed battery capacities by a factor of more than two during 2007. This milestone is very important, because the only way that batteries have been better than capacitors is in their ability to store more energy.
Capacitors (and ultracapacitors) can charge much faster than a battery, discharge much faster (meaning, they can give more energy on demand), and in normal use, they do not wear out at anywhere near the rate that batteries do. They are less dangerous to handle in terms of acids and explosive gasses. They are considerably more environmentally friendly to dispose of and to manufacture, and it is worth noting that ultracapacitors are 100% re-usable. When a device fails, you can pull the ultracapacitors out and put them in something else until (or if) they actually fail. I mean this in the sense that a 7-year old ultracapacitor will work just as well as a brand new one of the same specifications, where a 7-year old battery most certainly will not.
Ultracapacitors can perform as the exact functional equivalent of a battery in a circuit — that is, as a primary source of current and voltage — with the exceptions that they have much longer life expectancies, better performance over time, and a different, but not problematic, output voltage to remaining power relationship. Batteries such as a lead-acid car battery will maintain an output voltage reasonably near 12.6 volts for most of the time the battery is discharging under load. This characteristic is a consequence of the chemical process that actually produces the output, so it is an inherent characteristic of these batteries.
Ultracapacitors steadily drop in output voltage as they discharge, so a very lightweight device called a switching power converter may be placed between the ultracapacitor and the devices it is providing power to. This provides a precise (more so than a battery) output voltage right up until the ultracapacitor is fully discharged. In this way, the one electrical difference between batteries and ultracapacitors is easily, reliably, and inexpensively overcome.
Power Converter Use
There is another benefit to this arrangement. Because the output voltage of an ultracapacitor is directly related to the amount of charge remaining, measuring the output voltage of an ultracapacitor or ultracapacitor bank directly indicates the amount of charge left, unlike the estimates that must be made for a battery, which continuously become more inaccurate as batteries age. Batteries can "lie" to us, showing full output voltage when they have very little power left to supply. Ultracaps can't do that.
1.3.2 - Electric Cars
The only thing keeping electric cars from being completely practical now is conventional battery life, and ultracapacitors should resolve that within the next few years. Ultracaps are already nearing standard battery capacities (they were at about 10% as of 2006, which was very close considering they have been increasing in capacity exponentially), but large battery equivalent ultracaps have not been commercialized as yet. The primary hurdle that needs to be overcome is single unit ultracaps that can function in the 100% or higher power equivalent range while taking up the same volume and unit weight as the equivalent amount of batteries.
Once you can fully charge an electric car in the same time you can fill it with a liquid fuel, pull virtually any amount of current you need for accelleration, exceed a 300-mile range for a one-charge excursion, and never have to replace the ultracaps (a huge cost advantage over batteries)... that'll be the death knell for liquid fuels.
You performance freaks will like this. With an electric vehicle, you can build in virtually any amount of horsepower and torque. In fact, some of the most powerful vehicles made today use electric motors for power. You probably think of them as "diesel" locomotives, but if you look a little closer, you'll find that what they actually are is a huge diesel powered electric generator set that drives a 100% electric motor system at the engine's wheels. Doubt me? Look it up!
Ultracapacitors have another advantage over batteries in a vehicle; because of the high rate at which they can accept charge, they do a much better job at capturing energy from regenerative braking systems. This is a technology that turns a vehicle's forward motion back into electricity when you use the brakes. Because batteries can only accept charge at a comparatively slow rate, regenerative braking cannot work as well with them. Ultracapacitors make regenerative braking more practical.
Think about it: The distribution network is already in place (electicity) and once in use, not only does it obsolete all the fuel tankers running around, it allows us to migrate at any rate we see fit to 100% air-pollution free energy sources from nuclear (major) to tidal, solar, wind, and other minor, but still useful, sources. You'd never come up to a service station again and find they are "out of fuel" and for what amounts to a pittance to purchase the charging equipment, you can charge your car at home once a day in probably a few minutes. More often if you're willing to go for a high-capacity electrical service... charging an ultracap could pull amazing amounts of energy, quickly, if you require a quick charge.
Considering that charging an ultracap based vehicle would pull far more energy than the typical 10 KW electrical service a home has, the way a practical home charging station would have to work is by constantly pulling current from the home service in a co-operative manner (pulling current when other devices aren't, particularly at night) until it contains a full charge; then when you plug the car in, the charging system would "dump" that charge to the car quickly, and begin recharging itself again, to be ready to re-charge the vehicle again in 24 hours. Most times, the vehicle won't need a full charge, as typically it will not have traveled 300 miles. So most charging stations will just pull a fraction of the current possible, the majority of the time. That, combined with charging at night when the overall demand for electricity is much lower and available generating capacity is high, will allow the existing electrical distribution network to service a very large number of electric vehicles before additional capacity is required, either in terms of transmission lines or power plants. Public charging stations are another matter and will have to be located near substations in order to deal with the demands they will make.
The issues associated with the high demands of recharging is one of the reasons why there will still be service stations. Service stations can invest in higher powered electrical services, while also storing energy locally in their own ultracapacitor banks like a larger version of the home setup just described for those times when demand exceeds supply. The other key reasons are that many vehicles will be away from home and will require charges at odd hours and locations, or close intervals if running long distances, and that vehicles will still require lubricants, window washing fluid, and high-powered systems will still require coolants and so forth. And you'll want snacks!
As an investor, my money is in ultracap firms. Not ethanol or hydrogen. IMHO, both of these technologies are going to be a technological blip on the radar. Just barely.
20 years from now, if you see a fuel-powered vehicle on the road once a day, I'd be quite surprised. Why? Because once those fueling stations are no longer profitable to operate, fuel-dependent vehicles will go from scarce to gone overnight. How will you get enthanol, or gasoline for that matter, when there are no fueling stations and no tankers carrying fuel? And if you can't get fuel easily, why would there be any cars that used fuel, other than antiques?
1.3.3 - Why hydrogen can't compete
Hydrogen has a number of problems. First of all, the molecule is so small that it is very hard to store and transport, and is almost impossible to put into a pipeline. It can literally leak through metal. Secondly, creating hydrogen is a process that costs more energy than we can get back, and I'm not talking about just a few percent — it is very inefficient. Third, the energy density in hydrogen that we can recover chemically (meaning, in a non-nuclear manner) is very low compared to power we can create for ultracaps via, for instance, a nuclear power station. Fourth, to get energy densities that are high enough to get your car to go the usual cruise distance (about 300 miles), the hydrogen has to be compressed so hard that only very specialized equipment can compress, store and otherwise handle it. We're not talking about a light gas anymore, we're talking about a liquid compressed to a degree that is difficult to imagine. Lastly, there is no transport infrastructure and no fueling infrastructure.
Since all of these problems are inherent, and can only be solved by the application of large numbers of expensive technologies, it appears to me that hydrogen as a fuel is "right out."
Since everything — and I mean everything — is already in place that is required to support a nation of electric cars, barring the cars themselves, clearly the path of least resistance (hah!) is to go pure electric using ultracaps.
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