This does appear to be a
legitimate contender for grid power storage.
The most important factor is that it is inherently cheap and naturally long
lived. Since it is for grid storage,
weight is then irrelevant.
As my readers are aware, outright
grid level power storage is largely unavailable and has made optimization of
loads problematic from the beginning. We
simply have not had the option of storing energy during off peak times, nor
have willing users had that option.
After all storing energy can be attractive to the user, if not more so
because his economics are at retail rather than wholesale. It would also allow a portion of the capital
cost to be laid of to the customer.
From the description if appears
that they have shippable product. In
that case expect to hear a lot more about them.
Other protocols are naturally
expensive and are generally poor contenders.
This is presently closest to the price points needed.
New Battery Could Be Just What the
Grid Ordered
A Pittsburgh
WEDNESDAY, SEPTEMBER 28, 2011
Utilities need cheap, long-lasting ways to store the excess energy
produced by power plants, especially as intermittent power from solar and wind
farms is added to the mix.
Unfortunately, the batteries
available for grid-level storage are either too expensive or don't last for the
thousands of cycles needed to make them cost-effective.
A new
battery developed by Aquion Energy in Pittsburgh uses simple chemistry—a
water-based electrolyte and abundant materials such as sodium and manganese—and
is expected to cost $300 for a kilowatt-hour of storage capacity, less than a
third of what it would cost to use lithium-ion batteries. Third-party tests
have shown that Aquion's battery can last for over 5,000 charge-discharge
cycles and has an efficiency of over 85 percent.
The company has now received $30 million in venture capital to step up
manufacturing of its sodium-ion batteries. The new technology could be the
cheapest way to store large amounts of energy for the power grid using
batteries, says Jay Whitacre, the company's founder and chief technology
officer.
Aquion's battery uses an activated carbon anode and a sodium- and
manganese-based cathode. A water-based electrolyte carries sodium ions between
the two electrodes while charging and discharging. The principle is similar to
lithium-ion, but sodium ions are more abundant and hence cheaper to use.
Compared to solvent-based electrolytes, the aqueous electrolyte is also easier
to work with and cheaper. Even better, the materials are nontoxic and the
battery is 100 percent recyclable, Whitacre says.
Grid-scale trials of the technology are
next. Aquion has started shipping pre-production battery prototypes to off-grid
solar power companies. Next month, a 1,000-volt module will go to KEMA, a Dutch
energy consulting and testing outfit, which has a facility outside Philadelphia
Utilities use stored energy to meet electrical demand during peak usage
periods, a practice called peak shaving, which helps keep the grid reliable and
efficient and electricity prices low. Whitacre says Aquion's battery is
designed for these grid applications. "It's very well-suited for
off-grid solar and wind support, and also for peak shaving," he says.
"It's two very different applications, and our battery has been shown to
be effective in both."
John Miller, an electrochemical capacitor expert and president of
consulting firm JME in Shaker Heights, Ohio, says Aquion's battery could be the
cheapest of the various battery technologies vying to provide grid storage. He
compares it to today's most common grid storage technology, pumped hydro, which
accounts for 95 percent of utility-scale energy storage. Pumped hydro involves
moving water to an elevation when electricity demand is low, and releasing that
water through turbines during peak periods. It is, however, limited by geology
and space, and pumped hydro systems take many years and millions of dollars to
build. Utilities are now starting to look at batteries because
they can be delivered in months and, in principle, can be sited anywhere.
"Lead-acid is even too expensive," Miller says.
"Aquion's technology is getting to the range of pumped hydro in cost, which
is two cents per kilowatt-hour [over the system's lifetime]. They're unique. I
would say it's very promising for grid storage."
So far, no available technology meets all grid energy storage
requirements, says Haresh Kamath, a program manager for energy storage at
the Electric
Power Research Institute. "Each technology has a different sweet
spot" in terms of cost, safety, reliability, lifespan, and efficiency, he
says.
Some power companies use lead-acid batteries and sodium-sulfur
batteries for grid storage. Lead-acid batteries are cheap but only last for 500
to 1,000 cycles, while sodium-sulfur batteries are costly at $1,000 a
kilowatt-hour. Other technologies on the horizon—lithium-ion,above ground compressed
air storage, and flow batteries—remain
expensive and unproven.
Grid-storage battery technology also "has to be plug-and-play, and
not require extensive installation," says Ali Nourai, an executive
consultant at KEMA. Aquion's batteries may have the disadvantage of being as
large and heavy as lead-acid batteries, Nourai says, but their low cost and
long cycle life make up for that. "The biggest barrier to grid storage is
cost, and Aquion has an upper hand there," he says. "People will
tolerate low efficiency and high weight if the price is right."
Kamath says that the sodium-ion battery is an interesting new technology,
but grid-scale demonstrations will tell whether it has what utilities are
looking for. "More than any other, this is a very early stage technology,
and we don't know what it's capable of," he says. "Based on
principle, it looks very promising, and that's why a lot of folks in this
industry are excited about this. But it remains to be seen if the promises are
actually played out."
Whitacre has ambitious plans for Aquion, though. The company is making
35-watt-hour units that are modular and stackable at its research and
development facility. Next year, the company wants to produce multiple
megawatt-hours' worth of batteries at this facility, launch its first
commercial product, and break ground on a 500-megawatt-hour capacity factory.
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