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USC team develops novel organic redox flow battery for large-scale energy storage

Schematic of ORBAT. Click to enlarge.

Scientists at USC have developed a novel water-based Organic Redox Flow Battery (ORBAT) for lower cost, long lasting large-scale energy storage. An open access paper on their work is published in the Journal of the Electrochemical Society.

ORBAT employs two different water-soluble organic redox couples on the positive and negative side of a flow battery. Redox couples such as quinones are particularly attractive for this application, the researchers said. (Quinones are oxidized derivatives of aromatic compounds.) No precious metal catalyst is needed because of the fast proton-coupled electron transfer processes. Furthermore, in acid media, the quinones exhibit good chemical stability. These properties render quinone-based redox couples very attractive for high-efficiency metal-free rechargeable batteries, they found.

Since grid-scale electrical energy storage requires hundreds of gigawatt-hours to be stored, the batteries for this application must be inexpensive, robust, safe and sustainable. None of today’s mature battery technologies meet all of these requirements. The vanadium redox flow battery is one such battery technology that has reached an advanced level of development for grid-scale applications. However, the limited resources of vanadium, the high expense associated with the cell materials, and the toxicity hazard of using large quantities of soluble vanadium, have been the major challenges to the widespread adoption of the vanadium redox flow battery.

Aiming to overcome these disadvantages, we have demonstrated for the first time an aqueous redox flow battery that uses water-soluble organic redox couples at both electrodes that are metal-free. Such a battery has the potential to meet the demanding cost, durability, eco-friendliness, and sustainability requirements for grid-scale electrical energy storage. We have termed this battery an Organic Redox Flow Battery (ORBAT).

—Yang et al.

In ORBAT, two different aqueous solutions of water-soluble organic redox substances such as quinones are circulated past electrodes. The positive and negative electrodes are separated by a proton-conducting polymer electrolyte membrane. In the paper, the researchers a solution of 1,2-benzoquinone-3,5-disulfonic acid (BQDS) for the positive electrode; the negative electrode uses a solution of anthraquinone-2-sulfonic acid (AQS). By choosing the appropriate organic redox couples for the positive and negative electrodes, they projected that a cell voltage as high as 1.0 V is possible. The quinones have a charge capacity in the range of 200–490 Ah/kg, and cost about $5–10/kg or $10–20/kWh, leaving ample scope for achieving the US Department of Energy’s target of $100/kWh for the entire battery system.

The batteries last for about 5,000 recharge cycles, giving them an estimated 15-year lifespan. Lithium-ion batteries degrade after around 1,000 cycles, and cost 10 times more to manufacture.

—Professor Sri Narayan, corresponding author

Narayan collaborated with Surya Prakash, Prakash, professor of chemistry and director of the USC Loker Hydrocarbon Research Institute, as well as USC’s Bo Yang, Lena Hoober-Burkhardt, and Fang Wang.

The tanks of electroactive materials can be made as large as needed—increasing total amount of energy the system can store—or the central cell can be tweaked to release that energy faster or slower, altering the amount of power (energy released over time) that the system can generate.

While previous battery designs have used metals or toxic chemicals, Narayan and Prakash wanted to find an organic compound that could be dissolved in water. Such a system would create a minimal impact on the environment, and would likely be cheap, they figured. Currently, the quinones needed for the batteries are manufactured from naturally occurring hydrocarbons. In the future, the potential exists to derive them from carbon dioxide, Narayan said.

The team is currently testing testing and analyzing the behavior of other redox couples in the quinone family, assess the impact of solubility on full cell performance, and optimize the structure of the membrane-electrode assemblies. Solubility is still a challenge for this type of redox flow battery, they noted.

Choosing a substituent such as sulfonic acid to modify both positive and negative electrode materials appears to be the most promising approach at this time to meet the challenge of solubility in water. However, understanding the effect of substituent group type and placement on the standard reduction potential and kinetic reversibility are also important areas for further study.

—Yang et al.

The team has filed several patents in regards to design of the battery, and next plans to build a larger scale version.

This research was funded by the ARPA-E Open-FOA program (DE-AR0000337), the University of Southern California, and the Loker Hydrocarbon Research Institute.


  • Bo Yang, Lena Hoober-Burkhardt, Fang Wanga, G. K. Surya Prakash and S. R. Narayanan (2014) “An Inexpensive Aqueous Flow Battery for Large-Scale Electrical Energy Storage Based on Water-Soluble Organic Redox Couples” J. Electrochem. Soc. volume 161, issue 9, A1371-A1380 doi: 10.1149/2.1001409jes



Thank you for walking straight into my trap.  Your reference states this in section 4.0:

Capacitor does reduce energy consumption. In both cases, the reduction in system kWh loss is around 1.6%, as shown in Table 1.

This is not remotely close to the 25% you claimed.  It was not possible for capacitors to cut consumption by 25%, because total grid losses in the USA are only about 7% (see the column "T&D Losses and Unaccounted for".

Next time, read your reference material more closely.


Total grid losses are only 7%? Again you are not making sense because you insist on starting fights to show your imagined prowess. How do you count a "loss?" You give me a stale EIA chart, and this House Salad counts as an objective technological opinion?

Consider that reactive power accounts for 30% of gross grid energy. This scale of energy is made in excess of any anticipated demand, so as to prevent the grid from shorting out. That losses on current AC networks are 9% over an equivalent DC network. Outmoded and unreplaced transformers fail to live up to their potential of wasting only 1% of electrical energy. Given the fact that most households are inadequately electrified for modern electricity demand, Amory Lovins has estimated that proper diameter of copper wiring alone will reduce electricity demand by 6%.

The paper I have brought up mentions PF, or Power Factor, a well known price incentive to cut electricity use. A similar concept, which we would call the Operational Capacity Factor, pays consumers not to use electricity at all. The kinetic losses of starting and stopping a generator are astounding: As much as 40% (courtesy a rather old reference, David Pimentel's energy anthology from the 70's). Competing demand of intermittently operated HVAC causes power fluctuations that BLC's are best geared to deal with. Ever see a brownout?

Note that "Case 2" saves more than 10 times the actual NPV Loss of Case 1. This reflects fuel savings. The degree of fuel v. capital savings should be ascertainable on your utility's prospectus.

Anything that reduces all of these losses in a concerted way, saves fuel, allows higher voltages (and lower resistance losses, although I once calculated that doubling grid voltage will save only 1.4%) and minimizes blackout risk is welcome. The math suggests that "loss" defined by EIA is way understated.

A merchant rep I spoke to claimed that your personal computer will actually run cooler on BLC's. That is a tad exuberant. But PC's and many other devices cannot operate without capacitors, inverters, and transformers. That suggests a degree of redundancy between the grid and appliances, to allow for extensive additional power management.

That is reason for you and me to continue plumbing the research in this area.

Look forward to talking to you again, chum.

Just don't tell me how much you saved on your electric bill with all those incandescent bulbs you hoarded.



PF of electric motors ranges from .95 down to .60

That suggest that a nice round figure of .76 may be characteristic of many industrial concerns -- or of restaurants and other institutions with multiple refrigeration units, fans, rheostatic devices, and (defective) stepdown transformers. A .95 figure would be noble to acheive, particularly if you haven't got the time or the money to replace or upgrade a three-phase electrical system.


Just don't tell me how much you saved on your electric bill with all those incandescent bulbs you hoarded.

Funny you should mention that.  I've "hoarded" some Lights of America circlite ballasts which failed catastrophically, with an eye toward replacing the blown parts and finding a way to modify them to shut down gracefully as the bulb died.  For years I was stymied by the odd, hard-to-find component values and un-labelled devices.  Now it looks like I'm just going to toss everything as it dies and replace with LED, except in those few applications which are too sensitive to RF interference.

Total grid losses are only 7%? Again you are not making sense

Since you are too obtuse, I direct you back to the reference for these figures for 2013:
T&D Losses and Unaccounted for: 279 TWh
Net generation total: 4058 TWh

279 / 4058 = 0.0687, just under 7%.

Consider that reactive power accounts for 30% of gross grid energy.

Reactive power is imaginary power.  It is voltage and current in quadrature.  Over one cycle, it integrates to ZERO.  You can generate reactive power with a capacitor (utilities do that a lot).  Capacitors generate no real power; they actually consume small amounts of it.  The thing called a "synchronous condenser" is just an over-excited synchronous motor.  If it runs without a load it will still consume real power for windage, resistive and eddy-current losses, but generate reactive power.

There's a reason why transformers are not rated in watts, they are rated in volt-amperes (VA).  The point at which a transformer overheats or saturates its core is not set by the real power it's transmitting, but the total volt-amperes (square root of real power squared plus imaginary power squared).  A wire heats up proportional to the square of the RMS current, whether it is in phase or in quadrature phase (or from harmonics).

The reactive power consumed by motors and other inductive loads doesn't do anything except increase the losses in wires and transformers and reduce the real power they can move.  This still costs money, which is why utilities bill big consumers for it.  Utilities try to generate reactive power relatively close to the load, which reduces the reactive component of the current and the associated losses and limitations at points upstream.  If the consumer takes care of it on their side of the meter, the utility doesn't have to.

Note that "Case 2" saves more than 10 times the actual NPV Loss of Case 1.

If you bothered to read that closely you'd realize that it's all about utility billing rates, not losses in the system.

Now, stop trying to dabble in electrical power engineering until you've actually learned something about it.



You may have danced around the point, but you haven't actually made it. You have thrown EIA's figures about 'waste' in electric power at me, without considering what waste is -- energy expended in unuseful work. Utilities that do not generate power with modern integrated steam turbines are not expected to account for "waste" when they recommission old coal boilers. That is a political decision. Dispense with old generating capacity to do the same amount of useful work and that cuts waste.

The more you toss facts around the more we scratch our heads. "Reactive power is imaginary power"? I was not aware that perpetual motion was achieved on the grid. Reactive power is budgeted so that you do not turn a generator on because a toaster is on. And we are canny enough to realize that any current generates its own resistance, which is why the quadrupole concept has been adapted to grid wiring. But theory hits reality in the face when you realize that perfect waveforms do not exist by the time you reach the consumer level. If they did, we would not be having this discussion.

"Capacitors generate no real power,they actually consume small amounts of it/but generate[s] reactive power." We agree, so what are you gnashing your teeth about? Well, a capacitor does not generate power at all, but holds it long enough to generate necessary and sufficient power for the next step (possibly a transistor) and smooth the power supply.

I'm glad you admit that "a wire heats up" at all. viz those copper windings in 200 odd national grid transformers which no one has taken charge to replace or modernize on a timely basis. You can rate them as neatly as you want in volt-amperes with a nice hysteresis diagram thrown in (or with this blog, is it just hysterical?), but when you get enough waste heat to make a cup of coffee or fry your arm off, your science teacher will measure the watts.

Now you flip around and tell me that reactive power doesn't do anything except "reduce the real power they [wires and transformers] can move". If you took the other side and said there is no alternative to reactive power to avoid catastrophic failure, you'd have one over me. You might say that capacitors and power storage devices are in insignificant substitute for standby capacity or for secular fluctuations in power (my reading of one diagram is that this fluctuation occurs every four minutes, like movements in the stock market). But you don't, so I won't.

You might also say that BLC's are a fraud on the consumer, and there is some doubt about the current generation of APS's (advanced power strips). But you don't, and I won't.

I won't bother you with the Schneider Electric study, which is really a thought experiment, which I threw at you for your lazy blogging. You might however read the report in Science Daily, among others, that suggests The Grid has exceeded Haldane's Law on optimum size. If it did not, and there were not so many other neglectful features to it, there might be alternatives to BLC's

By the way, are you really an engineer? Or a poet?

I don't know what W.B. Yeats thought about engineers, but he did say: 'Philosophy is the argument one has with the world. Poetry is the argument one has with oneself"

You seem to be most intent on arguing with yourself. In any case, I'm done arguing this thread, as I am on holiday.

You might also say that BLC's are a fraud on the consumer
Never said that.  I just said you had no idea what it all meant.

As for the rest:

Now it's time for kiddies like you to stop running around the adult table.  Go play outside.


Reducing current extremely high energy waste in USA may be one of the best economic way to meet future energy demands at lower cost.

End-to-end system efficiency from coal fired power plants to domestic incandescent bulbs is a mere 1.6%.

Average end-to end efficiency of current fossil fuel based electric power generation in USA is a mere 22%.

Average well to wheel ICEVs efficiency is between 14% and 18%.

Using HVDC smart grid and distributed DC could increase reliability and increase system efficiency from 22% to well over 44%, specially for increasing DC demands for LED lighting, TV, Phones, PC, Cells, Tablets, Cloud centres, Data Centres etc.

Using BEVs and local high efficiency solar energy systems with DC storage could increase e-energy efficiency from 22% to well over 50%

Could it be that Tesla was wrong with HVAC grids some 120 years ago and that the time has come to switch to DC networks-grids (EU and Asia is doing it) and DC home-office-building distribution for our future DC machines and DC storage facilities?

Why convert future clean renewable power generating facilities from DC to AC and back to DC again, unless you want to spend $$$$BB in converters and more $$$$BB in wasted energy?

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