Flow Batteries: The future of high-capacity energy storage?

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Flow Batteries: The future of high-capacity energy storage?

Postby tigerbay » Fri Jan 10, 2014 3:41 am

Found this today about a new type of chemical battery being developed called a Flow Battery that has mainly been used in large-scale renewable grid energy storage. It mentions that until recently these were only available as more expensive models due to the cost of vanadium. However they are starting to perfect a simplified technique to use Quinone and other organic compounds in a chemical "broth" that can do the same more efficiently for a fraction of the cost.
What are people's thoughts on this development in regards to future electric vehicles?


" Cheap Battery Can Store Energy for a Rainy Day: Quinone could make flow-battery technology competitive with current storage methods
By Mark Peplow and Nature magazine

Power harvested from the Sun and wind is pouring into electricity grids by the gigawatt. That makes it ever more important to find an efficient and convenient way to store renewable energy for those times when the breeze dies or the skies cloud over.

“Now we have a good chance of solving that problem,” says Michael Aziz, a materials scientist at Harvard University in Cambridge, Massachusetts. His solution is a flow battery that packs a high energy density with no need for the expensive metals found in other models.

Flow batteries work by pumping different chemical broths over two electrodes separated by a membrane. The chemicals exchange protons across the membrane and shuttle electrons around the circuit that connects the electrodes, which discharges the battery. Reversing the reaction recharges the cell (see diagram at the bottom).

The big advantage of flow batteries is that the chemicals can be stored in tanks outside the battery assembly. Increasing capacity is simply a matter of building larger tanks, making flow batteries particularly suitable for large-scale energy storage.

The most advanced commercial flow batteries rely on vanadium ions. A handful of vanadium flow batteries are in operation around the world, and last year in Japan, where solar power is surging, the Hokkaido Electric Power Company ordered the world's largest vanadium flow battery. The battery should be ready in 2015.

“The problem is, vanadium is really expensive,” says Aziz.

Power pack
Over the past few decades, researchers have investigated many other chemical systems, and ruled all but a handful out. “The periodic table has been pretty well picked over,” says Aziz. “So we’ve introduced the world of organic chemistry to this problem.”

His battery’s anode uses a solution of sulphuric acid containing a type of organic compound known as a quinone. The quinone is cheap and needs no catalytic urging to react with protons to form a higher-energy hydroquinone, thereby charging the battery. Aziz teamed this half of the flow battery with a well-known partner: a cathode that alternates between bromine and hydrobromic acid.

The quinone–hydroquinone reaction is about 1,000 times faster than the rival vanadium reaction, allowing the battery to charge and discharge rapidly. And by changing some of the quinone’s chemical groups, Aziz can alter their solubility and even the voltage of the flow battery, fine-tuning the system. The battery, unveiled today in Nature, has completed 100 charge–discharge cycles with no sign of degradation (although a commercial system would probably need to top 10,000 cycles).

Aziz reckons that his flow battery could store one kilowatt hour of energy in chemicals costing $27 — one-third the price of the rival vanadium system. Further improvements could make it competitive with other technologies for storing vast amounts of energy, such as compressed air.

“I just wish I’d thought of it, because it’s such a simple system,” says Robert Savinell, an electrochemical engineer at Case Western Reserve University in Cleveland, Ohio. “And the simplest ideas are often the most effective.”

Organic solution
The system is far from perfect, however: bromine and hydrobromic acid are corrosive, and could cause serious pollution if they leaked. “The bromine is, right now, the Achilles heel of this particular battery,” Aziz says. The answer could be to go completely organic, he adds: “We are working on replacing the bromine with a different quinone.”

He has funding from the US Advanced Research Projects Agency—Energy (ARPA—E) to develop the concept into a large prototype “about the size of a horse trailer” within three years. His team is also working with clean-technology company Sustainable Innovations of Glastonbury, Connecticut, to commercialize the flow battery.

It is not just energy companies that are interested in flow batteries. “The biggest market at entry level is for industries that want to lower their electricity bills by buying cheaper power at night, and using it for manufacturing during the day,” says Savinell.

Cheaper flow batteries could even be teamed with household solar arrays, adds Aziz. Using a system no bigger than the 2,000-liter heating-oil tanks that are already installed in many homes, he reckons, “it's plausible to store a day of solar energy, and power your home in the evening”.

(Picture Adapted from Wang, W. et al. Adv. Funct. Mater. 23, 970–986 (2013).)

In a flow battery, two liquids are pumped from separate reservoirs to undergo reactions and exchange positive ions across a membrane, generating electricity. In charging mode, the reaction is reversed.

This article is reproduced with permission from the magazine Nature. The article was first published on January 8, 2014.

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Re: Flow Batteries: The future of high-capacity energy stora

Postby GregsGarage » Fri Jan 10, 2014 3:15 pm

tigerbay wrote:What are people's thoughts on this development in regards to future electric vehicles?

Hugely important as long as you don't waste time trying to fit the technology in a EV. Grid storage systems will allow widespread adoption of renewables, being able to store the energy when it is generated and using it when needed eliminates the main downside to renewables. For electric cars having a grid store battery near say a motorway services should allow rapid charging of many EVs at a time (10s, 100s, maybe more?) without stressing the electricity grid. And finally they could help keep the lights on with the existing grid. Lots of reports in the news about the possibilty of the U.K's power grid being near to max capacity with very little excess capacity to meet sudden unexpected peak demads. Grid storage batteries could help meet sudden peak demands.

So, yes it is important for EVs, renewables and even the existing fossil fuel powered grid. Have a look at the Ted Talk by Donald Sadoway who has been working on a liquid metal battery, another contender in grid storage batteries.

Greg Fordyce

Daewoo Matiz

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Re: Flow Batteries: The future of high-capacity energy stora

Postby Beemer » Thu Jan 30, 2014 8:41 am

I had a sigh over it when it was announced ages ago. The king has no clothes.

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Re: Flow Batteries: The future of high-capacity energy stora

Postby eco-wheels » Mon Jan 26, 2015 4:02 pm

Use to work on these in mid 90's at National Power for load levelling so this is hardly a breakthrough and quinone/hydroquinone couple is as old as the hills.

I'm sure things will have changed over the years but I would just like to qualify some of the statements.
1. Yes the bromine/bromide redox couple is corrosive and toxic but National Power have the patent on this when used in redox flow cells anyway so bod could only use this tech under licence.
2. If they haven't found a replacement for the Nafion membrane at what use to be $1000/sq metre the cost of Vanadium is peanuts in comparison. Even with cheap redox couples the biggest outlay probably still is the cost of the membrane - ie this bod will still have the same issues in relation to cost
3. The article reads as though a few people have tried the odd research project on this tech. In reality we had a fully operational pilot plant in South Wales which was then scaled up to a full working facility at Didcot. I left before this became operational (and before "the accident").
4. Put Nafion membrane into a lit search and it will probably return over 20,000 references - most are fuel cell related but an appreciable number refer to novel REDOX couples in flow cells - None of which have been cited

My humble opinion - This article should have been printed in a 3rd rate history journal rather than Scientific America/Nature. What ever happened to peer review?

I was always hopeful of using this tech in EV's. Go to fuel station & exchange your spent reactants with fresh or even regenerate them in situ at home. As bod says you would need less toxic REDOX couples. We used Brumine/Bromide with Sulphur/Sulphide - Not exactly the safest chemicals to let loose on Joe public :D

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Re: Flow Batteries: The future of high-capacity energy stora

Postby Beemer » Mon Jan 26, 2015 4:10 pm

Ummm, feeling there`s a disjoint here. Wasn`t these proposed batteries supposedly lithium and not a chemical cell?

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Re: Flow Batteries: The future of high-capacity energy stora

Postby eco-wheels » Mon Jan 26, 2015 5:36 pm

Hi Beemer

Most membranes in redox flow cells consist of a polymer matrix with channels lined with sulphonic acid groups. These will facilitate the migration of most cations across the cell - in our case we used sodium but the cell could work with Lithium or Potassium. After I finished at National Power I did a bit of independent research in an attempt to create a crown ether based membrane that could have been used exclusively for Lithium ions due to size exclusion. Unfortunately, I only worked on this project for 6 months before taking paid research into organic/polymer LED's.

The beauty of these cells is they will continually provide power as long as you keep supplying them with appropriate electrolytes

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