California Event Shows Potential of Energy Storage
Arecent project in California may be the first of its kind—at least in the U.S.—
in which large-scale batteries actually fired
up a generator to restore grid operations
without a power feed from the transmission network or backup source, the utility
announced earlier this summer.
In May, the Imperial Irrigation District’s
(IID) new energy storage system provided
the electricity needed to get its 44-MW
combined-cycle natural gas turbine
going at the El Centro station. This is a
big deal in the expansion of energy storage capabilities, proponents say.
“From where I sit and what I know,
I’m not aware of anybody else able and
willing to do so,” said Mirko Molinari,
manager of distributed energy resource
development for GE Power, one of the
partners in the IID energy storage proj-
ect. “It was not a simple task.”
Energy storage systems play several roles
within the grid connection, from load
following to load smoothing to frequency
regulation. Now, at least in this case and
likely others to follow, it can play a startup
role before converting back to absorbing
power from the functioning grid.
“The biggest question is whether this is a
game changer,” said Matt Roberts, vice president of the Washington, D.C.-based Energy
Storage Association. “No, but it’s one of the
new value streams this system can deliver.”
Juggling all of those streams is exceedingly complex, GE’s Molinari pointed out.
Software and control systems must wade
through all the immediate and intermittent inputs of a grid system which is processing flow from renewables as well as
a gap develops in
IID’s energy storage system went
online in October
2016. The partners in the project
Partners LLC, ZGlobal Inc. and GE Energy
Connections (now part of GE Power).
Historically, an operative grid would
be restarted by a backup diesel generator
or some other form of generation, giving
the main turbine time to get going again
and synchronize and keep frequency
steady on the system.
The IID event proved that energy storage essentially could “jump start” the system. The process sounds something like
what happens to a car with a dead battery
but not exactly.
“Turbines need to rotate at certain
speeds to generate the right frequency,”
Molinari pointed out. “If you have more
production than load, the frequency goes
up. If more load then production, frequency does down.
“You need to put the energy somewhere
to stabilize the grid, otherwise the fre-
quency goes up and down too much.”
Some of utility-scale energy storage’s
biggest projects have come online in the
past year. GE and Southern California
Edison (SCE) put a unique battery-gas tur-
bine hybrid system—called the LM6000
Hybrid Electric Gas Turbine—into opera-
tion into generation units at Norwalk and
Rancho Cucamonga in March.
Black starting means not only that
energy storage gets deployed on the grid,
but that it can get the grid going again.
Industry insiders believe that is a huge
deal going forward.
“Batteries degradate; the point is how
much and how do you use it,” GE’s
Molinari said. “You need to be able to do
it in the context of the system and not
just batteries as a standalone.”