Talk:Flow battery

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EROEI for storage[edit]

1. What is the overall efficiency of these batteries, including

  • Amount of energy discharged divided by amount of energy stored?
  • 1 - (Amount of energy required to construct one of these batteries divided by the energy storage lifetime capacity)?

2. What are the natural resources required as raw materials and what is the world supply of these resources? Any of the supplies in volatile regions?

3. What are the costs of these batteries on a kWh of storage basis?

4. What are the non-linear considerations for the answers to the above?


Skyemoor 13:01, 18 January 2007 (UTC)

If anyone can answer any of the above questions, then that would be better than nothing. Skyemoor 18:54, 22 January 2007 (UTC)

The questions are rather general. A zinc bromine system has rather different characteristics to an all-uranium flow battery for example. The furthest developed systems are probably the zinc-bromine, vanadium redox and polysulphide-polyhalide. Other systems have been abandonned because of poor efficiency, high cost or great complexity such as the iron-chromium and zinc-chlorine hydrate. Laboratory round-trip efficiencies for some systems have been quoted at 80 - 90%. However, these figures may well be reduced in practice, depending on duty cycle and operating temperatures. Raw materials are very system specific. The reactors and fluid lines are typically made of inexpensive, readily-available polymers and elastomers. Redox flow batteries generally become more economically viable as the ratio of energy to power increases (more electrloyte to reactors). Ahw001 07:13, 6 March 2007 (UTC)

External Links[edit]

I added a link to a manufacturer of these types of batteries. It was removed as spam. I disagree with that. This is not exactly a well known topic and a link to one of the few big names in the field would help give some context. —The preceding unsigned comment was added by (talk) 23:24, 8 March 2007 (UTC).

Wikipedia is NOT a business directory. The article is not about that company. A link to their website does not add to the enclopedic content and is not appropriate per the external links guidelines. VRB Power Systems Inc. spammed before, and their links were removed, not only by me. Interesting that only 6 days after, a corporate performance training company, also Canadian, inserts the same links again. Femto 13:03, 9 March 2007 (UTC)
Very well I accept your argument, I hadn't read the external link guidelines. But please don't start with the conspiracy theories. I'm not affiliated with them, I read about them in the Clean Break clean tech blog.-- 19:56, 14 March 2007 (UTC)

Distinction from fuel cells[edit]

After reading both this article and the external links, I can't detect any difference between a “flow battery” and a fuel cell. Can somebody either rewrite the article to clarify this point, or merge it into the fuel cell article? (talk) 23:51, 15 December 2009 (UTC)

They are sometimes called "regenerative fuel cells". The ambiguity over what to call them is that, unlike fuel cells and like batteries, they can be (directly) recharged. I tend to avoid modifying WKPD articles so I just leave that as an FYI. MrG (talk) 17:31, 18 May 2010 (UTC)

Somebody please specify the meaning of "WKPD" as used above? Sure isn't the one given in the main namespace, and the WP namespace has no such entry. -- (talk) 19:45, 30 July 2013 (UTC)
There is no chemical, material, or operational difference between a redox flow battery and a fuel cell. A non-rechargeable electrochemical device is termed a primary cell while a rechargeable device is a secondary cell (see Linden & Reddy, Handbook of Batteries). A redox flow battery is better termed a secondary fuel cell or rechargeable fuel cell, just as NiCd and Li-ion are termed rechargeable batteries. Historically, all fuel cells were primary cells, and it was probably not envisioned that energetically practical, rechargeable fuel cells would come into existence. When they did, people probably deemed them more similar to batteries, resulting in the misnomer "flow battery," even though the operational mechanism was more akin to that of a fuel cell. Those who work with flow batteries or wish to understand how they work need to know that the terminology betrays the underlying physical processes. (talk) 22:24, 29 October 2014 (UTC)

Flow batteries are not complicated![edit]

As a retired chemical engineer, I am interested in flow batteries as a excellent means for storing electric current for intermittent renewable power sources, such as wind and photovoltaic. Nearly every article I read about flow batteries states that they are complicated when compared to conventional batteries or fuel cells. I object to this characterization, because a flow battery is really a simple chemical plant, requiring storage tanks, pumps and piping, and internal electrodes. They do not require high temperatures or pressures, if the soluble salts are properly chosen, and they are easily controlled by common process control instrumentation. They also require appropriate internal semi-permeable membranes, but a competent research lab, experienced in the topic, should be able to solve this problem.

Compared to a flow battery system, a conventional storage battery system seems to me to be a nightmare of acres of floor space, filled wall-to-wall with batteries (for example, a lead-acid battery system), connected by a maze of conductors and instrumentation wiring to monitor each individual battery. Such a storage system is not simple, when the ramifications of operational monitoring and maintenance are considered.

Flow batteries probably require rather large storage tanks to provide the KWHrs to cover periods of time when the motive forces for the system are not active, but this is nothing unusual for a chemical plant, nor should they be for a town or city-sized power user. Containment basins would probably be required to protect against leakages from the system, but, again, choice of the proper ions in the electrical cells should minimize the potential for hazardous chemical releases, and could possibly present no problem at all.

Another complaint about flow batteries is that they are ugly. Ugliness is in the eye of the beholder, of course, and to my eyes and mind, even a few million-gallon tanks would not be ugly during a week-long storm blocking the reception of solar radiation, if they kept my home and community fully supplied with power. To give an idea of scale, a 2:1 diameter to height vertical cylindrical storage tank with a working volume of one million gallons would be about 40 feet tall and 70 feet in diameter. This is considerably smaller than a football stadium, even if several tanks were required for storing adequate amounts of electrolytes. And, of course there is plenty of room for aesthetic design to cover up those ugly tanks, including the use of buried tanks or large pipes.

Given these consideration, I believe that an ambitious battery manufacturer should be very interested in developing a multi-megawatt flow battery storage system, and showing the public that yes, wind and water will provide plenty of reliable power for future communities. Why have they not announced one yet?

Stephen M Fass, PhD, chemical engineering Smfass (talk) 23:57, 16 May 2013 (UTC)

Flow batteries are indeed much more complicated than conventional batteries, like Zn/MnO2 or Pb-acid, although I suppose you could argue that Li-ion is no less complicated. A few points worth noting:
  1. Finding a suitable membrane is nontrivial. Crossover events nullify voltage and therefore waste energy. Vanadium systems do not require separating out mixed fuel and oxidant, since all species are interconvertible, but other chemistries are not so lucky. This is why you see many paired with Zn, since the Zn ions can be separated from the oxidant by plating them onto Zn electrodes. Most current vanadium research is focused on designing better membranes.
  2. Flow batteries are also composed of multiple cells and so have similar problems to the Pb-acid stacks you describe. However, they probably need fewer individual cells.
  3. Flow batteries have a number of complexities not seen in traditional batteries. Like fuel cells, flow batteries can suffer from poisoning events and electrode degradation. Aqueous systems using Zn must prevent H2 from forming at the anodes. Fuel/oxidant solubility and transport directly determine current density and always pose challenges for high-power systems. Different catalysts have different rates of electrochemical reactions (different "current-overpotential characteristics"). Precipitation events occur. Zn electrodes form dendrimers. Energy must be spent to move the fuel and oxidant through the reactor. Stored fuel and oxidant degrade over time.
  4. Your systems-level analysis did not include the following key information: "round-trip" energy efficiency (for combined charge/discharge cycle), changes to energy efficiency over time, lifetime cost, or cost vs. alternatives. These are the parameters that have prevented many flow battery start-ups from succeeding in the marketplace. (talk) 22:50, 29 October 2014 (UTC)

Too technical still? (Intro for general audience just added.)[edit]

Some gang of gurus please check whether this box can be removed now ;-))

TIA, HTH, -- (talk) 20:56, 30 July 2013 (UTC)

I agree--I found it informative and well written. — Preceding unsigned comment added by (talk) 15:28, 16 January 2014 (UTC)

pro and con list, where?[edit]

one section is tagged as such. Can't seem to spot any list though. Tag outdated? Remove?

-- (talk) 20:59, 30 July 2013 (UTC)

Subtitle applications misleading[edit]

I understand this is still quite experimental and all applications here mentioned are only potential future applications, but maybe for a few limited applications yet. For example "Storing energy from renewable sources such as wind or solar for discharge during periods of peak demand", with a reference, looks like "wow, that bloody problem of wind is now solved". You have to read the reference to find this a second hand reference, where the journalist establishes a link between experiments at Harvard with the need of storage in California. Looks nearly dishonest now. Would be perfectly honest it was made clear that "one may dream of storing, in some future, energy from renewables…" Dominique Meeùs (talk) 07:19, 1 March 2014 (UTC)

I should add that English is not my language. "Dishonest" is meant objectively, as a more expressive variant of misleading. It is NOT meant subjectively, about the authors. Dominique Meeùs (talk) 07:41, 1 March 2014 (UTC)

EnerVault Unveils First Of Its Kind Iron-Chromium Megawatt-Scale Flow Battery[edit]

This recent news article may provide a useful example and additional reference. See: Thanks! --Lbeaumont (talk) 11:55, 4 June 2014 (UTC)

Energy density of Quant/nanoFLOWCELL[edit]

The added text, and the reference, specify the energy density of the Quant/nanoFLOWCELL flow battery to be a nonsensical 600W per kg and/or liter. It literally does not mean anything in this context. 600W is a measure of power, not energy, a correct specification would be in watt-hours or joules or a similar unit. Rwessel (talk) 21:30, 2 September 2014 (UTC)

Yes, I changed it to Wh per kg, as stated in nanoflowcell press release. Gor (talk) 10:01, 4 September 2014 (UTC)

"with Aqueous Multielectron Oxidants"[edit]

The section "with Aqueous Multielectron Oxidants", was recently added. Other than being horribly formatted and filled with utterly impenetrable jargon, is there any evidence at all that this is real? A couple of patent applications are not sufficient evidence (per WP:PATENT are not generally reliable sources), the purported company doesn't appear to have a web site, and no news seems to be mentioning this. Rwessel (talk) 11:10, 24 December 2014 (UTC)

I have to agree with you. It looks like unsourced advertising material. There's nothing I can find backing it up. I'm going to just remove it before it gets forgotten and left in. Striker121 (talk) 04:53, 27 January 2015 (UTC)

External links modified[edit]

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Mega flow batteries[edit]

The phrase "mega flow battery" has been used in coverage of the "rhubarb battery" but what does it mean? It would be helpful to define in this article. Is it just a flow battery capable of handling megawatts of power? -- Beland (talk) 00:32, 15 September 2017 (UTC)