In my last posting about flywheel energy storage I speculated that since steel flywheels appear to be beating out carbon fiber composite flywheels in UPS (Uninterruptible Power Supply) systems, it might turn out that steel flywheels would be also be a better choice for grid frequency regulation applications. (Frequency regulation, by the way, is actually power regulation. The grid is set up so that mismatches between load and generation manifest themselves as changes in the frequency of the AC current.) A startup company called Amber Kinetics, which originated from a Stanford University Cleantech Entrepreneurship class, is targeting exactly this application with flywheel rims made out of steel wire (See this presentation). more
May 1, 2013
I first read about the possibility of using composites flywheel suspended in a vacuum as high energy storage devices nearly 30 years ago in an article in Physics Today. Since two of the companies (Pentadyne andd Beacon Power) at the forefront of this field have declared bankrupty within the last year and a half, one would have to say the progress in the commercialization of this technology has been glacial. more
Drs Manickam Minakshi and Danielle Meyrick at Murdoch University in Australia have developed a water based sodium ion battery. This is another version of the battery technology being developed by Aquion Energy about which I have previously written. The announcement article reveals only a small amount of information about the battery design: more
A number of industrial processes (e.g. steel production, air separation, oil refining, nitric acid production, ethylene oxide production, etc) which produce high pressure gas at high temperature use expansion turbines to extract energy from the gas either in the form of mechanical work or of electrical current. This fact suggests the idea of using compressed gas as an energy storage medium. Obviously the cost of the expansion turbine itself is not prohibitive or this technology would not be utilized in existing industrial processes. However, other economic consideration enter the equation when one considers the deliberate compression and storage of gas rather than utilizing compressed gas that is the natural product of some other industrial process. Among these considerations are: more (May 13, 2012)
A company called EOS is planning to manufacture zinc-air batteries for utility scale grid storage applications. Metal-air batteries which make use of oxygen in the atmosphere as one of the electrodes have long been known to have high energy density. Non-rechargeable zinc-air button cells are currently being commercially produced by a number of companies primarily for use in hearing aids. However, producing rechargeable zinc-air batteries has proved difficult. Among the problems with such rechargeable batteries are the formation of dendritric zinc structures on the anode during recharging (The dendrites eventually pierce the separator between the anode and cathode and cause the battery to short circuit.) and the clogging of the gas diffusion electrode by potassium carbonate evolved from the electrolyte solution containing KOH. According the this posting both of these problems have been solved in a laboratory setting by the use of non-aqueous electrolytes. more. (Oct 9, 2011)
A company called Aquion Energy has developed a new type of sodium ion battery which it claims has superior performance and economic characteristics compared to NGK Insulator's molten salt sodium sulfur (NaS) batteries. They are targeting large scale grid storage applications with this technology. more. (Sep 02, 2011)
A British company called Highview power is proposing to store electrical energy using liquid air as the storage medium. Electrical energy will be used to run an air liquefaction plant, and at a later time the air will be reheated, expanded, and use to power a turbine/generator. The discharging cycle can use ambient heat, but with higher temperature heat source better round trip efficiency can be obtained. Highview is planning to use waste heat from existing industrial processes in order to obtain better round trip storage efficiency. A prototype of the turbine generator powered by liquid air and waste heat is already in operation delivering power to the grid, but a fully integrated storage system with on site generation of liquid air is not yet operational. more (July 15, 2011)
Ultra capacitors utilize high surface area carbon particles surrounded by an electrolytic medium to store energy in the electric field created by charged particles residing on the carbon surface. Maxwell Ultracapacitors is a a leading manufacturer of such energy storage devices. Below are some characterics of the BCAP3000 capacitor taken from the K2 series datasheet: more (July 3, 2011)
Some time ago GE announced that it was planning manufacture sodium metal halide batteries for utility scale storage applications. They have now revealed that the metal/halide combination in question is nickel/chlorine, the same as that used in ">FZ Sonicks's Zebra batteries. Some information taken from Durathon Utilility Battery Brochure is listed below: more (June 25,2011)
A sister technology to NGK Insulators molten salt sodium sulfur (NaS)batteries is molten salt sodium nickel chloride batteries also called Zebra batteries after the trade name of their sole manufacturer, a Swiss company called MES-DEA. Like NaS batteries zebra batteries have a molten sodium anode separated from the cathode by a tubular solid electrolyte made out of beta-alumina. The cathode is primarily composed of nickel chloride (NiCl2) rather than of sulphur. During the discharge process sodium ions are formed in that anode and migrate through the solid electrolyte into the cathode. The primarily chemical reaction in the cathode is the exchange of Cl between NiCl2 and the sodium ions resulting in the growth of large crystals of NaCl. During discharge this process is reversed and the NaCl crystals decompose and the sodium ions migrate back into the anode. more. (June 16, 2011)
I have written previously about NGK Insulator's large format molten salt Sodium Sulfur Batteries which they are selling in the utility scale storage market. Trans Ionics Corporation is developing a new form of Sodium Sulfur (NaS) battery which they claim will have performance characteristics which will allow it to compete in the EV and PHEV markets. Some details about the design of these battery taken from their web site are given below: more (October 21, 2010)
I have written previously about Mechanical Electric Inc.'s plans of developing an energy storage system which employs elevated weights as the energy storage medium. For reasons which I gave in the previous posting I do not think that this system is likely to be economically competitive (Just as an aside I note that the Mechanical Electric web site has vanished, so possibly their plans are no longer extant). Another possibility for such mechanical energy storage is to dig a deep shaft in the ground in which a large weight can move up and down. Excavating such a shaft is likely to be cheaper than erecting a very tall free standing structure. A company call LaunchPoint Technologies Inc. has recently spun off a subsidiary called Gravity Power LLC which is planning to develop such underground energy storage facilities. Their patent portfolio includes purely mechanical system with weights and cables, but the technology they are pushing is a hybrid system employing a large solid weight and water in a new form of underground pumped hydro storage(I have discussed underground pumped hydro previously here). more (October 14, 2010)
I have written previously about pumped hydro storage which uses the gravitational potential energy difference between two reservoirs at different altitudes to store energy. The same concept of gravitational potential energy as a storage medium could be used with other substances than water. A while back I ran across the web site of a company called Mechanical Electric Inc. which is proposing to build this type of energy storage system. Below are some extracts taken from their web site: more (August 2, 2010)
Pumped hydro energy storage uses reversible hydro electric turbines which employ electricity to run backwards and pump water from a low elevation reservoir to a high elevation reservoir. At some later time the water from the high elevation reservoir can be run back through the turbines to produce electricity. The round trip efficiency (i.e. the percentage of the input electrical energy which is recovered during forward operation of the turbines in the range of 70% to 85%. more (April 28, 2010)
Deeya Energy is a company planning to manufacture flow batteries for electrical energy storage. As I have written before the promise of flow batteries is very long cycle life because the electrodes are inert and are not degraded by the chemical interactions which are taking place in the liquid electrolytes which flow past the electrodes and past the ion exchange membrane which separates the half cells of the battery. more (February 20, 2010)
Vanadium redox flow batteries are a potential low cost (relatively speaking at least) electrical energy storage technology. In flow batteries liquid electrolytes flow past solid electrodes which are separated by an ion exchange membrane which allows one of the charged species to move back and forth between the two electrodes (one direction of movement corresponds to discharge and the other charging). In pure flow batteries it is claimed that the solid electrodes inert and do not directly take part in the chemical reaction taking place in the two half cells, so that they are not consumed or degraded (or at least degraded only very slowly) by the chemical reaction occurring in the liquid electrolytes. For this reason flow batteries can potentially have very long cycle life compared to other kinds of batteries. more (January 24, 2010)
As I have written previously sodium sulfur (NAS) batteries are currently the leading commercial technology for large scale electrochemical storage of electricity. Another battery type which is being explored for large scale energy storage is zinc bromine flow batteries. Here are some details about three manufacturers of these batteries. more (December 27, 2009)
Lithium ion batteries are the dominant energy storage technology for mobile consumer electronics. In addition recent years have seen a tremendous flurry of activity trying to develop large format lithium ion batteres for the EV and PHEV transportation market. Can lithium batteries also compete in the large scale stationary storage market? Here is some information about four manufacturers who seem to think so. more (November 21, 2009)
Sodium sulfur (NAS) batteries are the only commericially mature, large scale energy storage technology which can be sited at arbitrary locations. Pumped hydro storage is also a mature form of energy storage, but such storage facilities can only be sited where there a suitable geographical location with high and low storage reservoirs. more (November 8, 2009)
As I discussed in a previous post, a practical demonstration of molten nitrate salt as a thermal storage medium for concentrated solar power (CSP) has already been achieved. However a variety of different storage media have been proposed. A company called Lloyd Energy Storage has developed a system based on high purity graphite blocks. Some details about this system taken from their web site are given below: more (November 1, 2009)
Concentrating solar power (CSP) systems which use concentrated sunlight to run steam turbines have been receiving a lot of attention in recent years as a potential low cost alternative to photovoltaic cells. Like all solar technologies the power delivery profile of CSP depends on the availability of sunlight. Adding energy storage to such systems increases their power delivery flexibility. Unlike PV cells CSP systems can potentially store thermal energy rather than electrical energy giving them a cost advantage in this area because sensible heat storage has lower cost than electrical storage in batteries. more (October 11, 2009)
The engineeing design group LaunchPoint Technologies has proposed a design for a hubless magnetically levitated composite flywheel which has the potential to be scaled up to very large sizes. Here are some details from the presentaion called Third Generation Flywheels For High Power Electricity Storage by O.J. Fiske and M.R. Ricci: more (September 26, 2009)
Flywheels With Low Loss Superconducting Bearings
I stumble across an article published on line by International Technology Research Institute at Loyola College in Maryland concering reasearch and develoment on low loss superconducting bearing for energy storage flywheels. Some details of this report are presented below the fold. (September 21, 2009)
Flybrid Systems Composite Flywheels for Regenerative Braking Energy Storage
A Britsh company called Flybrid Systems is manufacuring carbon composite flywheel systems for regenerative braking systems. (September 20, 2009)
Beacon Composite Flywheels for Requency Regulation
Beacon Power is manufacturing 25kWh composite flywheels for grid frequency regulation services. Whether or not their product can be economically competitive in this market remains to be seen. (September 14, 2009)
Pentadyne has been manufacturing high RPM flywheels as energy storage devices for UPS system since 2004. Here is some information about their product. (September 13, 2009)
Isentropic Pumped Heat Storage
UK startup Isentropic claims it has developed a new energy storage method that sound too good to be true and therefore probably is. (Sep 13, 2009)
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