It's a battery. Fuel cells consume the fuel and expel an exhaust. They are one time pass through systems. Batteries can be recharged. Although there are similarities between flow batteries and fuel cells. It also depends in this case whether the hydrogen is cast off after regeneration or stored for reuse.

I have an issue with the statement that this is a higher power battery, especially when they report power on the electrode area basis only. This technology is not a higher power density based on system volume than lithium ion.

Don't get me wrong, for a stationary system their power definition might be all that is pertinent but to make a comparison between Lithium ion for mobile applications and a flow battery is misleading. The flow batteries have reservoirs of charged or discharged liquid electron carrier material and multicell systems have the same stack/flow/plenums as would be typical of fuel cells, and so why they are even making comparison to lithium ion is beyond me.

A couple of better questions would be how much does it cost and how long will it last. The point is, how much does it cost to store an electron. For the stationary applications, that your only metric. You don't need energy density and you don't need power density except as those would minimize cost. Yes, I do see they quote the $100/kwh, which is very good, but they also say that is speculation. Quote "membrane-less flow battery may be able to cost as little as $100/kWh", translation when something "may" be able to acheive a specific cost target, it means they are not sure.

That all said, $100/kwh is about where utilities need the energy storage costs to be for broad economical implementation of storage for solar, wind , and peak shaving etc.

"MIT researchers have engineered a new rechargeable, membrane-less hydrogen bromine laminar flow battery with high power density."

The researchers REPEATEDLY called this a battery and never is the term 'fuel cell' mentioned - but what do they know..

@kelly:
They could call it either and be accurate.

They said:
'In addition to bromine’s low cost and abundance, the chemical reaction between hydrogen and bromine holds great potential for energy storage. But fuel-cell designs based on hydrogen and bromine have largely had mixed results: Hydrobromic acid tends to eat away at a battery’s membrane, effectively slowing the energy-storing reaction and reducing the battery’s lifetime.

To circumvent these issues, the team landed on a simple solution: Take out the membrane.'

http://web.mit.edu/newsoffice/2013/rechargeable-flow-battery-enables-cheaper-large-scale-energy-storage-0816.html

In practical terms where you are thinking of using this for grid storage, and recycling the hydrogen, then you are likely to call it a battery.
Where you are thinking of mainly supplying hydrogen, say in a vehicle, then you will probably call it a fuel cell.

The chemistry does not change although some of the engineering does.

HBr and Br2 are quite toxic or dangerous (acid), and you still need H2 and need a return to regenerate the HBr & Br2. For a (stationary) battery it may work, but for a fuel cell I'd simply use only use H2 and dump my waste on the street.

Of course the power industry regulates frequency.
Increasing use of renewables makes that ever tougher to do as they swing about a lot.
One tool which they have not had are cheap and durable batteries.
Lead acid are cheap but not durable, other chemistries are durable but not tough.
This is clearly the unmet need they are referring to, as anyone of normal intelligence should easily see.

Theoretically, if batteries were cheap enough they would allow power plants to run at optimum efficiency at a high enough output to meet average demand. I'd imagine that this would save some fuel...

Then again, the batteries would have to be pretty damn cheap AND efficient. That's a tall order.

Re: Germany swearing off nuclear--what a self-destructive policy! Turn off safe, low-carbon, reliable, cheap, base load generators in favor of expensive, unreliable, intermittent renewables. Build new coal plants to make it all work. What a great idea.

I suspect that a cheap Br/HBr flow battery would favor nuclear power more than unreliables.  Suppose that your flow battery costs $150/kWh and is discharged 50% each weekday and recharged 40% each weeknight, coming up to full charge on the weekend with 30% discharges Sat/Sun.  Each kWh of capacity takes 3.1 kWh of charge per week, returning it at 90% efficiency.  At 5% interest and 20 year amortization, you pay 8.2¢/kWh output for amortization.

If O&M doesn't cost much, this appears to be quite competitive.  Overnight nuclear power generated at 3¢/kWh could be stored and sold at upwards of 20¢/kWh peak rates, also avoiding any costs related to emissions and eliminating cost uncertainty due to fuel prices.

kelly, if you are trying to compete with the pro troll for off-topic comments and non-sequiturs, please don't.

“Cleanup Attempt At Japan's Fukushima Plant Could Release 14,000 Times As Much Radiation As Atomic Bomb ”

Classic fear mongering. Bombs, chemical or nuclear, hurt people by the sudden release of near people.

“The operator of Japan's crippled Fukushima nuclear plant is preparing to remove 400 tons of highly irradiated spent fuel from a damaged reactor building, a dangerous operation that has never been attempted before on this scale.”

Spent fuel and spent fuel pools were not damaged at Fukushima. The blow out panels above the spent fuel pools were blown out by the hydrogen explosion. Moving fuel assemblies to dry cask storage is routine. A small crane is used to move fuel assemblies on at a time. This is done underwater and requires about 7 feet of water to protect the operator.

“INADVERTENT CRITICALITY
"There is a risk of an inadvertent criticality if the bundles are distorted and get too close to each other," Gundersen said.”

Storage racks are designed to preclude that. Of course Gundersen knows that. Fear mongers always fail to explain how they would cause the dangerous thing to occur. Having done integrated safety analysis and initial fuel load at a nuke plant, I am an expert on this subject. If you picked up a fuel assembly and dropped in at one end of the fuel where there is not a storage rack to maintain. Here are mechanical and electrical interlocks to prevent that. Then you would have to do it over and over hoping no one would notice.

This is somewhat akin to committing suicide by jumping off a building with a parachute and drifting over the ocean to be eaten by a shark. If could happen right.

FOR YEARS, the Japanese and many of the world's experts have now tried to keep Tokyo and the Pacific from becoming a Chernobyl and still appear to be failing.

Appear to be failing?  The only problem they haven't handled neatly is tritium, which cannot be chemically filtered from the water pumped out of the plant basements.  This tritium could be trivially discharged into the Pacific ocean without materially increasing radioactivity (tritium does not bio-accumulate).  If they wanted to be ultra-careful they could put this water in tankers, mix it with salt to make dense brine, package it in plastic bags and sink it in some deep ocean trench.  Tritium has a 12.3 year half-life, so isolating this water for a couple hundred years is sufficient to get rid of it almost completely.

even "Rechargeable membrane-less hydrogen bromine flow batteries" are charged by the power grid and every time there seems to be energy progress KP carps a unsettling energy ad.

Forget the troll, deal with the facts.

Chernobyl went sour next door to Germany.

radiation from Chernobyl is a continuing problem for Germany.

No, the FEAR of radiation is a continuing problem for Germany.  There is no proof that the Chernobyl fallout itself has caused any actual problem.

Then the Japanese melted a few. Japanese reactors built with US designs.

Again, with zero radiation fatalities and no injuries outside the plant.  3 workers with beta burns (because they were sent into the plants with neither rad monitors nor proper protective gear!) fully recovered.  The phenomenon which knocked out the plants' cooling systems (tsunami flooding) is impossible anywhere in Germany, and the plants themselves are of the earliest commercial design.  It's as if the word "nuclear" induces panic.

Renewables are neither expensive nor unreliable.

Tell that to the German people who cannot afford electricity any more, and the neighboring nations installing switches to keep Germany from dumping its surges of surplus on their national grids.

Working with those limitations is simply an engineering exercise.

The engineering "solution" the Germans have hit on involves burning more coal.  Really "green".

hose plants will be more efficient, releasing less CO2 per unit electricity produced than are the ones they are replacing.

Instead of the nuclear plants, which emit ZERO CO2 in their operation.  This is a giant step backwards, and everyone except the ideological anti-nuclear "greens" admits it.