Super Capacitors

Super Capacitors

Within about the last decade there has been a rather interesting development that seems to be largely unknown in the everyday world, but that could have profound effects upon energy production and use in general, and electric cars in particular. This is devices refered to as super capacitors.
A battery stores chemical energy. A current passes through it and the energy drives chemical reactions. These can then be reversed to produce a current in the opposite direction. Batteries have been and remain quite useful, but they are limited. These chemical reactions take time, limiting the power that can be drawn and the charging rate, and generally, after maybe 1000 charge-discharge cycles, the battery is pretty well shot and has to be replaced. The electrolytes and other materials, such as lead and nickel, present real problems for disposal.
A capacitor stores electric charge. Charges (electrons) come in one side, others go out the other, and a potential (voltage) developes. The energy stored depends upon the voltage and the total charge. For conventional capactitors, the amount is piddling: most capacitors are rated in micro farads. The super capacitors can store orders of magnitude more, clear up to hundreds or even a thousand farads. A capacitor can be charged with no delay and most are limited only by heating of the leads if the power gets too high. They last practically forever, forget about charge-discharge cycles, and usually contain nothing of much problem for disposal.
It might be useful to look at some values using more familar units. Most electrictiy is bought by the kilowatt hour. That is 1000 watt hours. A kilogram is about 2.2 pounds. Forget capacitors. The typical super capacitor will store about .5 to 10 watt hours/kg. An outfit in Cedar Park Texas (EEStor) is claiming 200 - 300. A lead acid battery may store about 30, a Li ion battery about 120 - 150. Gasoline is about 12,000, which should give you some idea why it is such an excellent fuel. However, the thing to note is the EEStor super capacitors are claimed to have about twice the capacity of Li ion batteries. The price is already less and dropping, and they never wear out. An outfit in Canada, ZENNergy, is developing a car supposed to be on the market next year, with about 250 - 300 mile range and the ability to charge in 5 minutes. That would be with substation power, but the 250 mile charge could be had at home in about 10 hours.
Now that is a very, very interesting development if they can pull it off. With 250 miles you can cross Missouri, Kansas City to St Louis. A 5 minute charge on the road at 200 mile intervals, would be quite practical. Remember, this would be at about 1/5 the cost for gasoline, and the vehicle should be very simple and reliable, and cheap also.
Speaking of pulling it off, Lockheed - Martin has recently agreed to partner with EEStor, and considering what Lockheed has acomplished over the years, that makes me rather confident they have something. It also helped ZENNergy as their stock jumped about a third. On the other hand, the Chevrolet Volt is slipping and is now rather disappointing. Estimated price up from $20 - $30,000 to $40,000, which is too much, the 3 cyclinder 1 liter engine getting 50 mpg, now up to a a 1.5 liter 4 that will probably get only 40, which is not impressive, and the latest ad I saw said 2010, up from Nov 2009. The ZENN will also beat the 100 mile range Nissan.
The capacitor is mainly used for voltage smoothing and is important for ocillators. The super capacitors (SC) can be used for power smoothing, and that could be important.Of all the forms of "alternative energy" generaly mentioned by activists, only wind has any potential, and that is only if the very real problem of sporatic availability can be solved. For a given wind generator, the power output goes up and down, and if you have a lot of them it could drive you crazy trying to match the generated power to the load. If a bank of SC is provided at each generator, or a bigger bank for each farm, then while the wind is blowing, part of the power could be put on the line, the rest going to charge the SC. Then when the wind dies, draw from the SC bank. This could make wind power practical, provided you could afford enough SC. Remember, there are likely to be still days, and you have to have the needed capacity on line, even if the wind hasn't blown for awhile, so SCs are not the compleate answer.
Whereas there is easily enough wind for all our needs, provided it can be harvested and smoothed out to match the demand, solar is needed for food. However, that in deserts could be used, and that which strikes buildings is wasted anyway. Solar panels taking the place of roofing could provide a lot of power where it is needed, particularly for home air conditioning, provided you could smooth it. Put panels on the roof and a SC bank in the basement, and you might get by most of the time. Charge up the SC bank when the sun is shining, use from it when it is not. I like the idea of using the sunlight falling on a house to run the air conditioning for that house, but this would also require the SC bank to be affordable. You also would probably have to have electric power from outside anyway, and that spoils much of the reason for going to the trouble. Nevertheless, it could reduce the generating capacity needed for the country.
Another way to smooth wind power would be to use hydrogen. Now I cannot see hydrogen as a practical fuel for cars because of all the problems distributing it and carrying enough of it around. However, if your wind farm was right next to a hydrogen plant, excess power while the wind is blowing could be used to electrolyse water. The hydrogen could be stored in large tanks, then fed to big fuel cells to generate electricty as needed. With a stationary plant, storage is much less of a problem as the weight and size of the storage tanks would be of little concern, and much higher pressures could be safely used that could be for a car. If days worth of hydrogen could be stored, then the changing of the wind would be no problem, just set things up for the average.
Something that would be better would be to convert the electricty from wind farms to liquid fuel. Sort of like photosynthesis, but using electricty rather than sunlight for energy, and converting carbon dioxide and water to alcohol or hydrocarbon instead of to carbohydrates and proteins. Methanol would be about the simplest and would have the bonus of being able to be used in a direct fuel cell. This fuel could be collected and transported to be used for transportation fuel, or it could be used to generate electricty as needed. It being then replaced according to how the wind blows. Liquid is easier to handle and store than gas, and this could provide several days worth, giving much better power smoothing.
I am no organic chemist, but I have noticed a lot of the simpler reactions seem reversable just using different temperature, pressure, and catalyst. The overall reaction would be: 2CO2 + 4H2O -> 2CH3OH +3O2. If the fuel cell reaction can be easily reversed, that might be the way to go: CO2 + 3H2 -> CH3OH + H2O. The hydrogen could easily be obtained by electrolysis of water. That I know needs no special conditions, just an electrode, such as platinum, that can stand up to pure oxygen. Of course you would have the problem of separating the water from the methanol. That can be done, and the water could be sent back for electrolysis again. The oxygen is useful, but might be produced in such large quantity as to lower its price such that it would simply be dumped into the atmosphere. No one should complain about the oxygen, and the CO2 alarmists should appreciate the use of CO2. Ideally, that would be from the atmosphere, but at 350 ppm, that is awfully scarce, so it would probably be better to locate next to a coal fired plant and use the CO2 from its stacks. Excess could be strored in tanks when the wind doesn't blow.
The only way to make wind power practical for large scale usage is some form of power smoothing, and this seems best.