

Iron-Chromium Flow Battery Aims to Replace Gas Plants - pwg
http://spectrum.ieee.org/energywise/energy/the-smarter-grid/new-flow-battery-aims-to-replace-gas-plants

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XorNot
Be interesting to see how they're solving the cross-contamination problem.
Iron-Chromium batteries fell out of favor because once the electrolytes mix
(and they always do) the cell is done.

The vanadium-redox battery was an advance because with the same electrolyte on
both sides you don't have that problem (but vanadium is expensive in this
application).

Last I heard there'd been some significant progress on house-scale iron-air
flow cell type systems, which is the one I'm really excited about - no cross-
contamination to worry about their either.

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reitanqild
Interesting, especially for its benefits for solar power.

(One sentence sticks out though: ". The company projects it can deliver energy
for utilities and other users at a cost of less than $250 per kilowatt hour."
This must be a mistake?)

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ndonnellan
Storage energy, not cost per unit of production. For example, to store 1 MWh,
it would cost $250,000 to build the storage. That cost would be amortized as
suggested below.

Since solar and wind are still very small parts of the energy production
industry, it's not clear what utilities will pay for pure storage (at least,
not the last time I checked). Places like Hawaii, where the PV concentration
is very high, might be interested.

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mikeash
Even absent solar and wind, aren't there some fairly substantial costs
associated with fluctuating demand? I'm not particularly knowledgeable about
this stuff, but I seem to recall that even among traditional methods of
generating power, the cheaper forms tend to be less able to respond to quick
changes in demand. Beyond that, there's also the fundamental conflict between
average and peak demand, meaning that a lot of generating capacity (and thus
capital expenditures) sits idle a lot of the time, and just exists to be able
to handle those few days when the temperature hits 105F and everyone runs
their air conditioners at full power all day long.

I have no idea how those costs stack up against $250/kWh for storage systems,
but it's at least conceivable that this stuff could be worthwhile even absent
any significant solar/wind deployment.

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ginko
How does this compare to pumped-storage hydroelectric plants? Those usually
have a conversion efficiency of 70-85% and can deliver serious capacity/power.

I guess good places for solar and mountains aren't always close together.

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twic
Presumably you can also implement a pumped storage system with a massive hole
in the ground, using that and the surface as the two levels. A use for old
mines, maybe?

Or maybe even for those persistent mine fires that were posted today. Two
birds with one stone. Prior art, of a sort:

[http://en.wikipedia.org/wiki/Lake_Peigneur](http://en.wikipedia.org/wiki/Lake_Peigneur)

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maxerickson
The pumped storage plant in Ludington, Michigan doesn't have a whole lot of
head, 363 feet. It's basically just an artificial reservoir at the top of a
hill by Lake Michigan.

[http://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power_...](http://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power_Plant)

