IEEE Electrification - December 2021 - 35

is difficult to go more than a few days
without reading about a new breakthrough
in this field, the consensus of
industry experts is that these new solid-state
Li batteries will not enter fullscale
production for electric vehicles
until approximately 2025.
For these emerging technologies,
there is a need for a common framework
for manufacturers to characterize
their systems and for prospective
users to evaluate them. That framework
is provided by IEEE Std 1679,
IEEE Recommended Practice for the
Characterization and Evaluation of
Energy Storage Technologies in Stationary
Applications. Even though the primary focus is on battery
technologies, the standard is applicable to other
storage media that provide a means for the reversible storage
of electrical energy; that is, the systems that receive
electrical energy and are able to release electrical energy
at a later time. The standard forms a foundation for the
objective evaluation of an energy storage technology by
providing a common basis for the expression of performance
characteristics, treatment of life-testing data, analysis
of failure modes, and assessment of safety attributes.
Revised in 2020, IEEE Std 1679 is supported by a growing
series of subsidiary guides to its application for different
classes of batteries. The published guides include IEEE
Std 1679.1 for Li-based batteries and IEEE Std 1679.2 for
sodium-beta batteries. Other guides are in preparation for
flow batteries and alkaline batteries. The following paragraphs
provide additional detail on each guide.
x The initial release of IEEE Std 1679.1 was in 2017, and
there is a move underway to revise the document to
reflect the changing qualification environment and
emergence of newer technologies, especially solidstate
Li batteries.
Revised in 2020,
IEEE Std 1679 is
supported by a
growing series of
subsidiary guides to
its application for
different classes
of batteries.
broad range of chemistries with nonflowing
alkaline electrolytes, many of
them zinc-based. The current list
includes zinc-air, nickel-zinc, nickelmetal
hydride, nickel-iron, and
rechargeable zinc-manganese dioxide.
Although nickel-cadmium chemistry
technically fits in this grouping, these
batteries are excluded because they
are already well characterized and
covered by other IEEE standards.
The IEEE Power & Energy Society
Energy Storage and Stationary Battery
Committee remains on the lookout
for other classes of energy
storage technologies that could be
covered by a guide in the 1679 series. The base standard
covers emerging and alternative technologies, where
emerging technologies are those recently, or soon to be,
made available for sale under customary commercial
terms (e.g., defined scope of supply and warranted performance).
The alternative technologies are those that
are currently mature but less well known or frequently
deployed as traditional technologies. These definitions
keep the committee focused on technologies where prospective
users are genuinely in need of guidance in their
evaluation, rather than on those that have yet to emerge
from the laboratory.
x The sodium-beta batteries covered by IEEE Std 1679.22018
include high-temperature sodium-sulfur and
sodium-nickel chloride technologies, typically operating
at around 270 °C. This group of technologies may
soon be expanded with the potential development of
new material capable of conducting sodium ions at
just above the melting point of sodium metal.
x Flow batteries are the subject of the standards project
that is likely to be published next year as IEEE 1679.3.
This document will cover a broad range of redox and
hybrid flow chemistries. There is much interest in this
class of batteries, especially when required discharge
times start to exceed 4 h. It is thought that these longer
discharge times will favor these technologies and
that they will finally emerge from the shadow of Li-ion.
x The project for alkaline batteries is P1679.4, where " P "
denotes a not-yet-published standards project, and
has just commenced. This document will cover a
(Inter)Connecting the Dots
It is one thing to develop safer and well-characterized
ESSs, but interconnection can remain a barrier to largescale
deployment. The potential concerns with ESSs
depend on the level at which the interconnection is
made. In the distribution network, distributed energy
resources (DERs), including ESSs, are often set up to
export power to the grid, and there is a concern that if
this export continues when the grid has failed, numerous
problems could occur, including a potential safety
issue for line workers, who may be unaware that a feeder
is still energized. An additional concern relates to the
performance of grid services by aggregations of distributed
systems, where the dispatch signal can shift rapidly
between charge and discharge, potentially creating disturbances
on a feeder. On the plus side, a grid-forming
ESS can be the lynchpin of a microgrid, providing resilience
to a facility that is normally grid-connected but can
disconnect as needed and function independently, provided
that the microgrid has sufficient control and protection
systems to meet the requirements of both
on- and off-grid operation. Having such a " sheddable
load " can be a benefit for the network operator, but the
transition to and from islanded mode must be achieved
without disruption.
At the transmission and subtransmission levels, the
concern is more over the loss of inertia in the bulk electric
IEEE Electrification Magazine / DECEMBER 2021
35
IEEE Electrification - December 2021

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