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Direct Energy Storage (Capacitor) Capacitive deionization need not transfer electrons to or from the ions clustered against the surface of the electrodes in a CDI cell. CDI will not induce oxidation or reduction reactions at either anode or cathode as long as the voltage differential across two electrodes is kept lower than the oxidation or reduction potential of the dissolved ions. This is a major insight and a profound benefit of Reticle Carbon—CDI merely arrests the flow of ions electrostatically and coaxes them out of the bulk solution to "stand gently against" the electrodes at the sides of the cell. Interestingly, the system comprised of the charged electrodes, the layers of charged ions, and the layer of uncharged fluid comprises a classic capacitor in the traditional sense. (In the parlance of electrical engineers these are known as "electrolytic capacitors".) Much or all of the energy stored in the two oppositely charged ion layers is recoverable. A Reticle Carbon CDI cell is nothing more than a mega-capacitor as long as there is no oxidation or reduction reaction or any other reaction in the cell that is parasitic to the stored energy. The potential size of the capacitor represented by even a modest sized Reticle Carbon CDI cell is colossal, absolutely enormous. All the capacitance resident in that cell is immediately available for charging and discharging. Capacitors are direct power storage devices. At present, metal-carbon composites are being manufactured in the automotive industry as a means of leveling the power draw in future electric cars. Such materials combine aluminum sheets and activated carbon in various configurations. The best in class capacity demonstrated to date is rather inefficient, storing a mere 7-10 kilowatt hours per kilogram of material. Given the cost of such materials, supercapacitors based on those materials are simply out of the question from an economic perspective, and the internal combustion engine continues to reign until the supercapacitor problem is solved. Reticle Carbon has in laboratory studies produced 7.5 kilowatt hours per kilogram of material in a 2 cubic inch capacitor (rather minuscule in size by Reticle’s standards). This was accomplished with a modest surface area grade of Reticle Carbon by Reticle standards (1200 square meters per gram). Reticle has manufactured much higher surface area carbon monoliths, and that higher surface area carbon has a higher power storage capacity. Because of the lightness in weight of Reticle Carbon, supercapacitors built from Reticle Carbon are considerably lighter than metal-carbon capacitors and therefore are ideally suited for mobile and transportation applications in which onboard weight is a prime consideration. This is not to be discounted. One of the primary markets for supercapacitors is the automotive market, a market that absolutely craves lightness in weight. Another is the airframe market, which craves lightness in weight even more. Reticle carbon offers lower capital cost, better operation, and lower weight added than present best in class. Small Reticle Carbon supercapacitors could provide enough energy to operate a computer, cell phone, etc. in consumer product markets. Several companies (Asahi Glass, Chrysler-Daimler, etc.) are actively engaged in ultracapacitor technology for supplying power for acceleration in new-age electrical automobiles. Future markets are estimated to be several hundred thousand automobiles per year. In addition, several companies are examining supercapacitors for powering cell phones, electric appliances, cordless power tools, etc. The market for supercapacitors is colossal. Furthermore, if a supercapacitor can actually be produced and demonstrated, it will be a primary catalyst for growing its own market. It is instructive to summarize Reticle’s findings regarding the capacitance of a standard Reticle Carbon CDI cell. It is estimated that a Reticle Carbon Cell comprised of an eleven electrode configuration that Reticle has installed in a test application has an estimated 435,000 Farads of capacitance! (This cell has a 2 foot by 2 foot cross section and is just under 4 feet long.) This magnitude of capacitance is almost inconceivable. That Reticle can pack this much capacitance into such a small volume is extremely significant if we can take full advantage of it. (If that test turns out to be valid, Reticle may have solved the problem of the ages, the problem that plagued Michael Faraday himself—how to store electrical energy.) If the capacitance of such a cell is as high as we have calculated it to be, when fully charged that cell is in effect a colossal "supercapacitor," and a supercapacitor of this magnitude has very high economic value. It directly stores a substantial quantity of electrical energy during normal deionization operation. From whence does this very high value derive? The most obvious value is as a load leveler on the electric power grid or a source of energy for another uncharged Reticle Carbon cell. Consider the problem facing the electric power grid. Consider that a fully or partially charged Reticle Carbon CDI can sell stored electrical energy whenever it wants, and it can accumulate additional charge whenever it wants. The Reticle Carbon CDI cell operating as a capacitor can if it wishes choose to sell power at precisely the time of electrical system peak, i.e., the time it can obtain the highest possible price for that power. Conversely, the cell operating as a capacitor can choose to buy power at times other than the time of electric system peak. This would result in Reticle acquiring power at the lowest possible price during time of off peak. To wit, suppose we were to charge the cell from 6:00 P.M. in the evening until noon the next day and discharge it into the daily noon-to-6:00 P.M. peak electricity market, thereby capturing for ourselves the differential between the off peak electricity price and the on peak electricity price (which can be very, very large at certain times of year). By so doing, we would be synchronizing the charge-discharge cycle of the Reticle Carbon CDI cell to the daily electrical on-peak-off peak cycle, and we would be purifying the water on a schedule consistent with that cycle. To do so is very appealing, for it has the potential to reduce the operating cost of our cell by a tremendous amount, maybe even all the way to or below zero. (Keep in mind, peak power prices can be $115/MWh or much higher while off peak power prices are $18.00/MWh and perhaps lower. This magnitude of daily price differential happens in North American power markets frequently.) Reticle Carbon CDI cells would, when running in a daily discharge on peak/charge off peak cycle, be akin to "pumped storage," which pumps water backwards and up over the dam at night and generates using the dam in the normal fashion during the day. Day-night electrical energy cycling makes a lot of money for the owners of pumped storage, even at the 70 percent efficiencies that characterize pumped storage. (Reticle Carbon supercapacitors promise to be much more efficient than that. There is no reason Reticle Carbon cells will lose energy other than parasitic or resistivity losses.) Keep in mind; peak power sells for 3-10 times what off peak power sells for. On a more immediate scale, the energy contained in Reticle Carbon CDI cells that are deionizing water can be recovered by transferring from cell to cell among a multiple installation of cells. For instance, two cells running in parallel can be operated in such a manner that the energy stored on one unit could be recovered during the charging of the second unit and vice versa. The regeneration of the first unit can be coordinated with the startup of the second. This, too, is a very appealing means of recovering a large percentage of the energy needed to remove ions. To wit, if each cell is a capacitor, you use the stored energy in one cell to charge a second cell. With regard to sustainability, supercapacitors open a whole new realm of sustainability. They can use solar, wind, or other renewable energy sources to charge and store themselves, just as they can use coal, nuclear, or hydrocarbon energy. With a pure supercapacitor, the Reticle Carbon CDI cell can be fully closed with no inlet or outlet, meaning there is no prospect of any release or any pollution. |
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