A
small group of highly educated geeks got together recently to talk about the
current state of research in utility-scale energy storage systems.
This
was a small conference of about 50 people, mainly chemical and mechanical
engineers, but also physicists, and others. A handful were students. Twenty
percent were women. The nationality list was enormous: Australia, China, Czech
Republic, Germany, Holland, India, Japan, South Africa, Spain, Sweden,
Thailand, and, of course, the U.S.
The
June conference, “Massive Energy Storage for the Broader Use of Renewable
Energy Sources,” was chaired by Sudhakar Neti of Lehigh University. and Trung
Van Nguyen of University of Kansas. Convener Engineering Conferences International ’s
technical co-sponsor was MEMC/SunEdison.
The
world of energy storage is amazingly complex. The conference dealt mainly with
chemical storage systems and heat storage systems, but also pumped
hydroelectric power, and issues like converting solar heat into liquid fuels.
Why
is storage important? Eighty-five percent of the world’s energy still comes
from fossil fuels, 6 percent from hydro, 5 percent from nuclear and only 1.9
percent from renewables.
But
renewables are the fastest growing category at 7 percent annually, and a lot of
renewables are intermittent. Thus they need storage to be able to play a
significantly larger role.
Hawai`i
is on the radar for these energy folks. They know about the Hawai`i Clean
Energy Initiative. They recognize that Hawai`i’s high electricity costs and
dependence on oil create a special demand for renewable energy storage.
Babu
Chalamala of Sun Edison, a major national solar contracting firm, said grid-scale
storage was not likely to be a big player on the U.S. Mainland. Rather, it
would be more likely to play a role in places with smaller, unreliable grids,
and in high-cost places like Alaska, California and Hawai`i.
It’s
not just Islanders who are aware of the high cost of power here. Hawai`i’s
costs were mentioned more than once by the Massive Energy Storage researchers.
I
would guess that when most folks think storage, they think battery, and most of
those batteries are chemical batteries.
Perhaps the most common example of a standard chemical battery is lead
acid—the battery in your car, and the battery most folks use who have off-grid
home power systems. Or lithium-ion, the battery that's in your phone and your laptop/
But
these kinds of chemical batteries aren’t the only kind of energy storage. Not by a long shot.
Another class of chemical battery is the flow battery, which differs from familiar
batteries in that a liquid electrolyte doesn't just sit there like in your car
battery, but is pumped through the battery. It is also different in that the
energy is stored in the electrolyte, while in a standard battery the charge is
stored on the electrodes.
At
this conference, there was also discussion of capacitors, an energy storage
device that takes a charge very quickly and discharges very quickly. These cannot
normally be used to deliver energy over time like a lead-acid battery.
But
there is work on hybrid capacitor systems, which use capacitors to charge an
electrolyte, which then can be used for long term energy delivery. The title of
a talk on this was “The Electrochemical Flow Capacitor: Grid Scale Capacitive
Energy Storage.” They’re being studied at Drexel University.
And, of course, there are many kinds of energy storage that have nothing to do with chemical batteries, like compressed air, pumped hydro, solar thermal, flywheels and lots more.
The
Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) grants
cash to researchers that are developing entirely new ways to generate, store,
and use energy.”
ARPA-E
doesn’t just fund anything—it’s not a vehicle for pure basic research. Its projects are designed to have ready application. The projects need to have a “road to market.”
ARPA-E
is looking for projects that develop storage at $100 per kilowatt hour, can
charge and discharge at least 5,000 times, have an 80 percent roundtrip energy efficiency,
are made of abundant raw materials and are recyclable. (http://arpa-e.energy.gov)
There's nothing out there right now that meets all those requirements, but there's lots of work underway on the subject.
As
this series progresses, we will doubtless be called out for not listing one or
another kind of storage. We’ll plead guilty right here. The list of energy storage
research areas is pages long and we won't get to all of them.
In
our next section, we’ll look at a few of prominent ones that came up at the Massive Energy Storage conference.
©
Jan TenBruggencate 2013
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