irregular discharging than lead-acid
batteries, according to O’Connor.
While lead-acid and lithium-ion
technologies duke it out over marginal
cost reductions and efficiency gains,
advances and improvements in flow
batteries may just be getting started.
Chueh, Baclig, and a team of researchers have developed a new type
of flow battery that could eventually
be a low-cost, high-power alternative
to existing energy storage methods.
According to Stanford, “The group
found a suitable ceramic membrane
made of potassium and aluminum ox-
ide to keep the negative and positive
materials separate while allowing cur-
rent to flow.” The membrane “doubled
the maximum voltage of conventional
flow batteries, and the prototype re-
mained stable for thousands of hours
With those advances, says Chueh,
“We aim to simultaneously achieve
high energy density, lifetime, and re-
However, this new flow battery is
still in the prototype phase. While
promising, it will not be mass-pro-
duced any time soon.
Another new battery type that is
commercially farther along in scaling the storage of renewable energy is
the zinc-air battery, a metal-air battery
powered by oxidizing zinc with oxygen
from the atmosphere. These batteries
have high energy densities, and are
relatively inexpensive to produce. Late
last year, energy storage technology
company NantEnergy and its billionaire founder Patrick Soon-Shiong announced they had developed a battery
that uses zinc and air to store renewable energy.
This zinc-air battery has been tested “in Africa and Asia, as well as cell-phone towers in the United States for
the last six years, without any backup
from utilities or the electric grid,” according to The New York Times. The
company claims the new battery can
store and release electricity at a cost
of less than $100 per kilowatt-hour
(kWh). In comparison, Elon Musk
told shareholders that Tesla was
working to get to that price point for
its lithium-ion battery cells by the
end of last year.
The $100/k Wh mark is seen in the
energy storage community as a tip-
ping point for widescale adoption of
electric cars, according to Bloomberg.
Despite these advances, commercially viable and scaleable grid-ready
alternatives to lithium-ion batteries
remain to be seen.
“Incumbent technologies are still
on a steep cost-down curve, which is
challenging for new technologies to
compete with,” says Chueh. However,
Chueh is confident that, given a long-enough timeline, alternative grid batteries will be part of the answer to scaling renewable power storage.
“Batteries used at the grid scale will
look more like a chemical plant, rather than the batteries used in electric
vehicles, drones, and robots today,”
Lead batteries for utility energy storage:
A review, Journal of Energy Storage,
Battery Showdown: Lead-Acid vs.
Lithium-Ion, Medium, Jan. 23, 2017,
Cheaper Battery Is Unveiled as a Step to
a Carbon-Free Grid, The New York Times,
Sept. 26, 2018
Renewable Energy Statistics 2018,
International Renewable Energy Agency,
2017 Hydropower Market Report, U.S.
Department of Energy, April 2018
Pumped-Storage Hydro Plants, Duke Energy
What’s the Difference Between Installed
Capacity and Electricity Generation?, U.S.
Department of Energy, Aug. 7, 2017
Logan Kugler is a freelance technology writer based
in Tampa, FL, USA. He has written for over 60 major
© 2019 ACM 0001-0782/19/3 $15.00
new battery technologies with higher
energy capacity, lower cost, and lon-
ger life, that can also be charged and
discharged fast, is very challenging.
Oftentimes you can improve one [fac-
tor] at the expense of others.”
This situation has researchers
hunting for alternative technolo-
gies to store energy from renewable
Alternative Energy Storage
There are many alternatives when it
comes to grid energy storage, says Antonio Baclig, a renewable energy storage researcher at Stanford and a member of Chueh’s team.
“Lithium-ion is now the frontrunner for grid storage batteries, but
lead-acid batteries are a low-cost alternative, and flow batteries are continuing to improve,” he says. Lead-acid
batteries are solid batteries used in
automotive applications. Rechargable
flow batteries, however, use liquids instead of solids to conduct electricity,
which may give researchers more options to find chemical combinations
that dramatically improve efficiencies
and reduce costs.
Lead-acid batteries have the “
largest market share for rechargeable
batteries,” according to research published in The Journal of Energy Storage
by Geoffrey May, Alistair Davidson,
and Boris Monahov. Much of the market for these batteries is in traditional
motor vehicles—standard car batteries.
While lead-acid batteries are relatively inexpensive and widely available, they do have some drawbacks:
for one, they are heavy, which makes
them less than ideal for electric cars
(Tesla’s vehicles, for example, use lithium-ion batteries.)
The real advantage of lead-acid
over lithium-ion has historically been
cost, but that is changing. Research
by Joe O’Connor, manager of application engineering at battery technology
company Farasis Energy Inc., showed
that while individual lead-acid batteries are cheaper to buy than lithium-ion batteries, the total lifecycle cost
for off-grid lithium-ion batteries is
reaching parity with that of lead-acid
Lithium-ion batteries require little
maintenance and are more resilient to