TRL Energy Storage System Features

                                             TRL CIR Battery Characteristics

                                           Salient performance features

 

Additional Advantages

     Completely reversible operation

     No memory or fatigue problems

     Can be left unattended indefinitely

     Virtually no operational failure modes

Among the many application possibilities for the ESD system, the following are listed.

For Full Flow Configuration

Wind energy storage

 Solar photo-voltaic

 Emergency standby power source

 UPS systems

 Load leveling

For Static Electrolyte, Sealed

 Small portable appliances & communication systems

 On-line for computers and controls

 User end storage for power peaking on demand

 Hybrid vehicle peak electric power and propulsion

 

 

Full Flow and Static Electrolyte System Comparisons

Redox cells with two electrolytes and all liquid reagents can be designed and operated as either static electrolyte systems or full flow electrolytes. In the first case the electrolytes remain in their respective compartments (negative and positive sides of a cell with a barrier or membrane separating the two compartments) as in conventional batteries.

The static electrolyte version of the redox cell offers the advantages of simplicity in design, no mechanically moving parts, and easily sealed. However, the energy and power densities of any particular cell design is a compromise because inter electrode cell spacing will affect both coulombic capacity as well as internal cell resistance and reagent availability for discharge. Also, charge retention time is significantly smaller because of ionic and molecular diffusion across the membrane separator.

In the full flow configuration the two electrolytes are circulated from reservoirs into and out of their respective cell compartments through appropriate manifolds and pumps as shown in the figure below.

The advantages of the flowing electrolyte design approach include;

• Indefinitely long charge retention times
• No cell imbalance problems with large cell arrays
• System can be electrically shut off by electrolyte draining
• Separation of energy capacity from power delivery parameters in system designs
• Ability to be recharged chemically by replacing electrolytes
• Electrolytes may be electrically recharged in an external device

In some applications the advantages of full flow redox may justify the necessary additional complexity and mechanisms.

In striving for the realization of a very long life secondary battery one of the developmental paths that has been followed is the use of reagents that remain in solution at all times. In other words, no deposition or removal or change of composition or structure of solid reagents at electrode surfaces in the energy storing process. There are very few choices of chemical components that have all the properties necessary to make it a practical electrochemical process.  Virtually all workable materials combinations have the singular drawback of having dissimilar materials on opposite electrolytes. And, since these reagents are in solution there is the inexorable transport of catholyte materials into the anolyte region and vice versa. In most cases there is no direct method of returning these unwanted components from one electrolyte to their origin.

 

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