Molten Metal Batteries Return for
Renewable Energy Storage
Sept 14, 2009 - Phil Taylor - Scientific American
The Streator Cayuga Ridge South Wind Farm NOT ALWAYS
BLOWING IN THE WIND: Energy storage is crucial
to handle the intermittent nature of wind power.
Image: Courtesy Energy.gov
EaglePicher Technologies, a manufacturer of specialized
batteries for military and space programs, is partnered
with the federal government to develop a powerful
battery storage technology to help utilities smooth
out the ups and downs of renewable power.
It's a familiar path for the Joplin, Mo., company.
EaglePicher began developing a battery for space
applications in the mid-1980s that used sodium and
sulfur components. Its model performed successfully
on the Columbia space shuttle in 1997.
But by then, the focus for military and space batteries
had shifted to lithium-ion models in the United States
and the impetus for a sodium sulfur battery vanished
in this country. EaglePicher mothballed its work.
Now EaglePicher is back in the game, working on
a sodium sulfur battery with the Pacific Northwest
National Laboratory (PNNL), backed by a $7.2 million
grant from the Energy Department's Advanced Research
Projects Agency-Energy (ARPA-E). It was one of 37
such awards made in 2009 to foster clean energy breakthroughs.
EaglePicher is funding the $1.8 million balance of
the three-year project.
With Energy Department research and development
budgets facing an uncertain future in Congress, the
future for such clean energy partnerships is also
uncertain. This week, ARPA-E will show off its grantees
at the 2011 Innovation Summit in Washington, bringing
together scientists, venture capital funders and
elected officials in a bid for political support
for President Obama's goal of producing 80 percent
of the U.S. electricity supply from clean energy
sources by 2035.
PNNL estimates that more than 200,000 megawatt-hours
of power from energy storage would be needed in 2030
if the United States were to get 20 percent of its
electricity from renewable sources then. The concept
is to store electricity made from renewable energy
when it is in surplus -- such as wind energy at night
-- and use it during during peak demand periods during
The characteristics of sodium sulfur batteries are
well-suited for that. While the technology was pioneered
in this country, but then abandoned, Japan saw the
promise and picked it up. Its Ministry of International
Trade and Industry chose it as a targeted opportunity.
Japan takes the idea and runs with it
Tokyo Electric Power Co. and NGK Insulators pushed
sodium sulfur development in the 1990s, and today,
NGK is the primary commercial manufacturer. U.S.
utilities seeking large storage batteries for renewable
energy can face a wait of a year or more.
It amounts to the second big battery technology
fumble the United States has been involved with.
The technology that underpins the ubiquitous lithium-ion
batteries in consumer electronics products was invented
by American physicist John Goodenough in the late
1970s, helped by a $20,000 grant from the U.S. Air
Force. Ignored by U.S. manufacturers, it was commercialized
by Sony and other Japanese companies in the 1990s.
PNNL scientist and project coordinator Gordon Graff
says the laboratory's partnership with EaglePicher
seeks to leapfrog NGK's design to perfect a more
compact architecture that could significantly boost
the battery's efficiency and performance while also
greatly simplifying the manufacturing process.
"This is a radical change in design," said
Graff, who holds 22 patents. "This is one of
the ways we can make this step jump."
In the PNNL facility in Richland, Wash., Graff hefts
one of the NGK batteries as he explains the opportunities
that PNNL and EaglePicher team hope to exploit.
The NGK battery is a cylinder with sodium in the
center, separated from molten sulfur by a ceramic
membrane that allows the passage of sodium ions to
create the battery's current. The tubular design
of the NGK membrane and casings simplifies maintaining
a secure seal on the volatile chemicals within the
battery, whose internal temperature reaches 350 degrees