Vanadium Redox Batteries

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Scupperer
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Vanadium Redox Batteries

Post by Scupperer »

The latest issue of Discover Magazine had an interesting article on recent developments of Vanadium Redox Batteries, so I looked a bit more into it.

Here's a link to their web page:
http://www.vrb.unsw.edu.au/
Or Wiki:
http://en.wikipedia.org/wiki/Vanadium_redox_battery

It's a pretty neat solution to energy storage and divergent from most current battery research, and it looks like they've solved some pretty big battery problems:

1. No cross contamination through ion-diffusion. It uses Vanadium electrolytes on either side of the element, so the element never corrodes.
2. It can be recharged an order of magnitude more times than conventional batteries. (1000's vs. 100's)
3. Since it's a flow battery, it can be recharged either by replacing the electrolytes, or electrically. Imagine an "Electrolyte Station", where the pump first empties your tank of spent fluid, then refills it with charged electrolytes. Or, you could just plug your car in at home and avoid the stop. I can't help but think of a future where "gas" stations have a BFR devoted to recharging spent electrolytes for Vanadomobile fleets.
4. They've managed to get the energy density to about 25 Wh/g, and think they can get it up to 35 Wh/g, which will put it on par with lead/acid batteries. Still nowhere near other battery capacities, but the other advantages might outweigh this.
5. Ability for high initial discharge rates (up to 400% of battery capacity), and full discharge capacity without damaging the battery.

Drawback: cost. Currently, the batteries costs about $500/kwh capacity.
This is solvable if they can garner enough interest to scale up production, which current investment in solar farms and wind farms should do. These alternative technologies will need storage for down times; storage that can kick in immediately and at high demands.

I'd love a house-sized one; one that could hold about 3 days worth of power after a hurricane blows through. Then I'd also invest in solar and just go gridless, right in the middle of the city.
Perrin Ehlinger

MSimon
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Post by MSimon »

I think the future of local off grid storage is flywheels. Unlimited charge/discharge cycles.

I can't figure out why this isn't being pushed harder.
Engineering is the art of making what you want from what you can get at a profit.

scareduck
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Post by scareduck »

MSimon wrote:I think the future of local off grid storage is flywheels. Unlimited charge/discharge cycles.

I can't figure out why this isn't being pushed harder.
Whose job, exactly, is it to "push" this? The government's? Maybe there's a technical/safety/economic/etc. reason these haven't been adopted.

djolds1
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Post by djolds1 »

MSimon wrote:I think the future of local off grid storage is flywheels. Unlimited charge/discharge cycles.

I can't figure out why this isn't being pushed harder.
Bada-BANG.

Flywheels have a tendency to delaminate and then disintegrate with explosive goodness.

Yes, gasoline ignites and burns us alive, but we're used to that one. Introducing a new "spectacular danger" is SCARY.

Duane
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MSimon
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Post by MSimon »

djolds1 wrote:
MSimon wrote:I think the future of local off grid storage is flywheels. Unlimited charge/discharge cycles.

I can't figure out why this isn't being pushed harder.
Bada-BANG.

Flywheels have a tendency to delaminate and then disintegrate with explosive goodness.

Yes, gasoline ignites and burns us alive, but we're used to that one. Introducing a new "spectacular danger" is SCARY.

Duane
Duane,

However for local storage you bury them in the ground. Which is why I made that specific suggestion.
Engineering is the art of making what you want from what you can get at a profit.

djolds1
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Post by djolds1 »

MSimon wrote:Duane,

However for local storage you bury them in the ground. Which is why I made that specific suggestion.
Ah.

I thought you meant off-grid vehicles.

Duane
Vae Victis

hanelyp
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Post by hanelyp »

For mobile use watt-hours/kilogram is important. For fixed point storage watt-hours/$ becomes a far more important metric. If the storage is twice as large and heavy it doesn't so much matter if it isn't being moved around.

If you can get a flywheel with good watt-hours/$ out of low tech steel, that's fine for fixed point storage, such as an off grid house.

MSimon
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Post by MSimon »

hanelyp wrote:For mobile use watt-hours/kilogram is important. For fixed point storage watt-hours/$ becomes a far more important metric. If the storage is twice as large and heavy it doesn't so much matter if it isn't being moved around.

If you can get a flywheel with good watt-hours/$ out of low tech steel, that's fine for fixed point storage, such as an off grid house.
I did an interesting spread sheet on this and the numbers look pretty good with 300,000 psi steels.

The mfg is pretty low tech (vacuum chamber similar to refrigerator design) size runs about 1 m high 1 m dia. And about 25 wh/lb.

I tried to get some money up to look into it but zero interest.
Engineering is the art of making what you want from what you can get at a profit.

jmc
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Post by jmc »

It seems others may have been more successful:

http://en.wikipedia.org/wiki/Flywheel_energy_storage

From what it says here, friction prevents the low cost/$ flywheels from storing energy for long enough to deal with intermittency in renewables. It also says here that if you evacuate the vessel they are in and use high temperature superconductors the period over which energy can be stored over increases. I imagine so does the cost/$....

I thought flywheels were already used for grid regulation.

Regard flow batteries, is there enough vanadium in the world to chemically store, TWh's of energy?

Scupperer
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Post by Scupperer »

jmc wrote:Regard flow batteries, is there enough vanadium in the world to chemically store, TWh's of energy?
Vanadium is a pretty common element (22nd most abundant on Earth); and its recovery is mostly a bi-product of mining iron. It runs $2 to $4/lb in the form of Vanadium Pentoxide, the most common naturally occuring form.

I don't know how refined, or what state it needs to be in for use as electrolytes in the flow batteries, but the element would probably be pure vanadium, which runs on the order of $10/lb, raw. I assume the current high costs are in the other components of the element, and in the solution for the electrolytes. It sounds like it could be brought down considerably in price if it finds a market to expand to.

Anyway, I think the answer to the question is "yes", if you have tanks large enough.
Perrin Ehlinger

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Post by MSimon »

Argonne did some interesting work with Halbach arrays. They thought they could get energy losses down to lead acid batter levels.
Engineering is the art of making what you want from what you can get at a profit.

Nanos
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Post by Nanos »


Scupperer
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Post by Scupperer »

A guy from VRB Power Systems called me the other day, after I left a request on their web page for more information.

Apparently, these people have licensed the technology from the Australian University that developed it, and they hold the license for most of the developed world.

After talking with him a bit, he said right now the company's focus is on large-scale uses for power plant load-leveling, and for remote uses (mostly telecom towers) which are currently powered primarily by diesel generators.

The remote units that they currently build are in the 5 to 20KW size range, and run about $50k, they recommend maintenance once per year, but replacement of battery components are expected in the range of 15 years. Pumps and tubes for the electrolytes may require more frequent replacement. How much time power is needed is adjustable just by changing the size of the storage tanks for the electrolytes. I neglected to get a price range from him on what the electrolytes themselves currently cost, either on a kwh basis, or a volume basis.

Primary use of the remote units, currently, is for telecom sites that run on diesel generators. Usually such sites have 2 generators, which are cycled for maintenance, and there's a big fuel storage tank. Maintenance is expensive, and fuel is expensive. Installing a VRB system apparently cuts fuel use, and generator use, by approximately 1/2; the VRB stores excess power during generator run times, and once fully charged, allows the generators to cycle off (or idle - not sure) while the telecom draws power off the VRB.

I asked him about whether they expected to hit a cost curve and see prices come down; he refused to commit to a time frame guess, but was naturally enthusiastic that they would.

So, I'll just keep watching these guys, and see what happens. A current whole-house back-up generator runs about $10-$15k (turn-key), so it's definitely not an economical consideration for personal use... yet. If they beat the $20k mark, then it might be worth consideration for coupling it up with some thin-film solar for residential/small commercial uses.
Perrin Ehlinger

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