This is in response to questions about the viability of wind and solar
generating systems without affordable bulk energy storage systems.  However
it should be noted, windpower is already viable. It is limited however, to
10 to 20% of total electrical demand due to it's intermittant nature.  As
electric power transmission and distribution systems continue to grow and
interconnect that figure may improve.

There are a number of energy storage systems currently available or on the
horizon.
Pumped hydro is one. The economic cost* is $500 to $1600/KW .  The DOE
notes that 22GW are installed at 150 facilities in 19 states.  The figures
given do not indicate cost/kwH so the price for a unit of actual storage
capacity is not clear.
In spite of it's expense, pumped hydo is seen as viable in some locations.
Another possibility is compressed air in existing geologic formations. The
cost* estimates are $350 to $500/kw.

*(all costs excluding VRB from DOE page below)

The DOE at,
http://www.eren.doe.gov/power/pdfs/append_overview.pdf

notes that:  "The most appropriate storage systems for such applications.."
(solar and wind)   " appear to be batteries."

The DOE lists two batteries as being commercially available, flooded lead
acid and valve regulated lead acid.  at 750 to 1000 $/kw and 500 to 600 $/kw
respectively.  Two other options listed as not commercially available yet
are zinc/bromine and lithium (utility scale). One remaining cost estimate,
400 to 600 $/kw presumably  refers to one or both of these.

Another battery option is the redox flow cell.  This page,

http://www.ceic.unsw.edu.au/centers/vrb/webframe/vanart2a.htm

By the inventor of the vanadium redox battery (VRB),  Dr. Maria
Skyllas-Kazacos , University of New South Wales, Sydney AU, gives a good
introduction to this system.

A shorter look can be had at:
http://www.sei.co.jp/sn/97_07.html

The redox system is a unique electrochemical storage system.
one of it's advantages is cost. From the first site:

"Cost estimates by the UNSW group and independent consulting groups (10,
11), place mass production costs at between $100 and $300 per kW for the
stack and $30 to $50 per kWh for the electrolyte."

For a large system,

" typical projected battery costs for 8 or more hours of storage being as
low as US$150 per kWh. "

Of all the options it appears that Redox is the cheapest.  This becomes even
more apparent when it is considered that the redox battery has a virtually
unlimited lifespan.
 Since all reactions take place in the liquid phase, there are no
irreversable chemical changes.  The only part of the system that needs
regular replacing will be the membrane, perhaps every five years. The
battery is not damaged by deep discharge or by rapid charge rates and can be
configured such that off-gassing of H2 does not occur as is the case with
lead acid batteries.  The efficiency is remakable, approaching 90%.  Total
storage capacity can be sized independent of power by simply increasing or
decreasing the electrolyte volume or by increasing or decreasing the number
of flow cells.  Charge and discharge can take place simultaneously and at
different voltages. This in effect makes the system a DC transformer.  By
electronically monitoring system voltage and switching cells on and off as
needed, it is possible to track an optimum voltage for PV  and wind
generating systems.
There is no energy lost with long term storage since the electrolytes are
stored separately.  A feature that holds great promise for electric
transport is the ability to recharge a redox battery by replacing discharged
electrolyte with charged thus recharging an electric vehicle in the same
time it takes to fill a fuel tank on a conventional vehicle.  The discharged
electrolyte can be recharged at off peak times from the grid.  Instead of
gasoline tankers delivering energy to filling stations we can use the
electric grid.

Even without wind and solar redox makes sense for load leveling, for large
scale consumers of electric power such as heavy manufacturing who can
purchase power at times of low demand.  Bulk energy storage will reduce or
end the need for expensive peaking generators by storing excess baseload
capacity in times of low demand. This will also allow more efficient
operation of baseload generators.

For windpower there is another benefit that may not be immediately apparent.
Having a means of storing energy will make it worthwhile to design machines
that can harvest power from higher but less frequent windspeeds.  Presently
this would result in short term spikes of power.
The energy of wind increases with the cube of the velocity.  There is a lot
of power out there that is presently too erratic to be useful. Having
storage allows this power to be salted away.  Also, as wind turbines grow in
size and height they will be capturing energy in larger chunks so to speak,
storage will only increase the efficiency and utility of these machines.
It would appear that the vanadium redox battery is the best choice as a bulk
energy storage option.  This combined with wind and solar may be our energy
future.

--
Windpower, over 13500 mw sold.

Assuming a 20% Capacity factor,
that's over 28,955 1980 F-100 equivalents !!

Regards , Tim O'Flaherty

 

Missing something.  The storage system is used more often
than it is paid for.

Comparisons of depleted vanadium electrolyte to boron oxide
are not favorable, however.  Boron oxide is a hundred times
lighter per uptakable kW-hr, costs less than a dollar, and
the boron that comes back is 300 times lighter.  So it makes
sense to consider shipping these substances to and from a
faraway wind turbine, while the vanadium solutions are thought
of only as sitting next to it, and regurgitating the electricity
in the same place they were charged.

 
---------------------------------------------------------------
$1 uranium = ca. $100 petroleum = ca. $68 natural gas. 
Electricity? Hydrogen?  No, the indirect nukemobile runs
on the fifth element, ~boron~.  More at
http://members.xoom.com/I2M/boron_blast.html.
---------------------------------------------------------------

Tim, thanks for an informative post.  I have to wonder, though, how
these cost estimates of $30-$50 per kWh and $150 per kWh will be
received in a world that is accustomed to paying $0.05 per kWh for
electricity?  Am I missing something in the translation, or will redox
storage really make electricity one thousand times more expensive than
it is today?

-dl

<snip links and summary>

thanks for the links on the redox storage, this will be fun to see the
replys from the pro-nuclear ones. i really cant see why so many people seem
to have such a problem with the true renewable energy sources, electric
cars are more reliable and simpler to service, with vanadium electolyte
cells recharging is fast and neat. all that is required is sufficent
capital to start the transition, it would be no more complex then the
changge to unleaded or the installation of LPG filling facilitys, probably
wold not cost as much as there is no risk of fire with electrolyte spills.
wonder what its toxicity is like as some escape into the environment is
unavoidable, electric car crashes rupturing fuel tanks and so on.

ant

We're not talking about electric generation here Don, we're talking about
storage capacity that is used over and over. In the case of redox it "keeps
on going and going and going"  You know, the redox rabbit. :^)

Yes, KWH generated is a measure of actual power, KWH storage capacity is
just the size of the "container" .  You can use the container thousands of
times.

--
Windpower, over 13500 mw sold.

Assuming a 20% Capacity factor,
that's over 28,955 1980 F-100 equivalents !!

Regards , Tim O'Flaherty

We don't need to ship them to faraway turbines.  We power the filling
station with the grid and recharge the electrolytes there.  It's obviously
cheaper to move power through wires than to truck discharged electrolyte
around the countryside.

No I don't think so, the redox storage could be sited anywhere it is useful,
at steel mills, car factories, windfarms, filling stations, remote  weather
data recorders, maritime beacons. The system is extremely versatile and can
be sized to suit any purpose.

--
Windpower, over 13500 mw sold.

Assuming a 20% Capacity factor,
that's over 28,955 1980 F-100 equivalents !!

Regards , Tim O'Flaherty

There is good info on Vanadium here:

http://www.vanadium.com.au/

It is toxic in high concentrations but is not considered a carcinogen and is
not easily absorbed through the skin. Vanadium poisoning can result from
inhaling soot.  The greatest source of vanadium pollution is oddly enough
soot from fossil fuels.  Through the lungs is the path, not likely with
solutions.

--
Windpower, over 13500 mw sold.

Assuming a 20% Capacity factor,
that's over 28,955 1980 F-100 equivalents !!

Regards , Tim O'Flaherty

Tsk, scorecard.org ranks Vanadium as one
of the most hazardous to human health (worst 10%)
and claims it is an immunotoxin.
It is a respiratory toxin and its release
is regulated in California, I believe.
Vanadium oxide is also considered a neurotoxin
and a skin toxin.

Where is the precautionary principle when needed... 1/2 ;-)

no.s...@tds.net ruminated:

Agreed, I was impressed. I didn't realize that battery technology was
so close to being viable for large scale powerplant storage. I still
have my doubts, but it's definitely worthy of much more
research. Stanford recently built on campus, next to the cogen
powerplant, a huge (I think they said it was the largest west of the
Mississippi) ice/chilled water storage facility which uses off-peak
power to produce ice/chilled water at night, which is used to provide
cooling for buildings in the day. Inexpensive storage is extremely
valuable.

What you missed was already explained in other replies. Anyway, I'd be
interested in seeing how such a system would add (or in some cases,
subtract, in the long term) to costs. Also note that the cost to
compare to would be peak power prices, which are typically much higher
(often $0.30/kWh and up, though i haven't looked recently).

That was surprising since the following source source, while noting problems
with inhaled vanadium don't seem all that worked up about it.  It isn't
easily absorbed , doesn't bioaccumulate and doesn't seem to be a carcinogen.
Oh yes,  It isn't radioactive.   :^)   You KNOW that makes me smile.

U.S. Department of Health and Human Services
Public Health Service
Agency for Toxic Substances and Disease Registry

http://www.ic.be/incin/vanadium.htm

How might I be exposed to vanadium?

Exposure to very low levels in air, water, and food
Eating higher levels of it in certain foods
Breathing air near an industry that burns fuel oil or coal; these industries
release vanadium oxide into the air
Working in industries that process it or make products containing it
Breathing contaminated air or drinking contaminated water near waste sites
or landfills containing vanadium
Vanadium is not readily absorbed by the body from the stomach, gut, or
contact with the skin.

How can vanadium affect my health?

Exposure to high levels of vanadium can cause harmful health effects. The
major effects from breathing high levels of vanadium are on the lungs,
throat, and eyes. Workers who breathed it for short and long periods
sometimes had lung irritation, coughing, wheezing, chest pain, runny nose,
and a sore throat. These effects stopped soon after they stopped breathing
the contaminated air. Similar effects have been observed in animal studies.
No other significant health effects of vanadium have been found in people.

We do not know the health effects in people of ingesting vanadium. Animals
that ingested very large doses have died. Lower, but still high levels of
vanadium in the water of pregnant animals resulted in minor birth defects.
Some animals that breathed or ingested vanadium over a long term had minor
kidney and liver changes.

The amounts of vanadium given in these animal studies that resulted in
harmful effects are much higher than those likely to occur in the
environment.

How likely is vanadium to cause cancer?

The Department of Health and Human Services, the International Agency for
Research on Cancer, and the Environmental Protection Agency (EPA) have not
classified vanadium as to its human carcinogenicity.

No human studies are available on the carcinogenicity of vanadium. No
increase in tumors was noted in a long-term animal study where the animals
were exposed to vanadium in the drinking water.

--
Windpower, over 13500 mw sold.

Assuming a 20% Capacity factor,
that's over 28,955 1980 F-100 equivalents !!

Regards , Tim O'Flaherty

Well, who are you going to trust, the DHSS or EDF?

It can be if you want. :-)

Check the EPA instead.

 ..