IEEE Electrification - December 2021 - 49

recently, battery applications have been limited to smallscale
usages such as uninterruptible power supplies, backup
in some applications, bridging with backup generators,
at-home applications, auxiliary services at power plants,
and so forth. Large-scale applications, such as grid- and
utility-scale batteries, have been mostly in lab development
up until the past decade.
The last 10 years have yielded an exponential increase
in the manufacturing and installation of large-scale batteries.
The main technologies in use have been sodiumsulfur,
vanadium-redox, lithium-ion (Li-ion), and lead-acid
batteries. For example, a 200-MW/800-MWh, vanadiumredox
flow battery-storage project is under construction in
Dalian, China, and will be the world's largest battery-storage
facility when completed. Li-ion batteries are widely
used and applied in a significant majority of grid-scale,
battery-storage projects. The world's largest solar (850 MW)
and battery system (531 MW/2,125 MWh) has been
approved for construction in the desert north of Las Vegas,
Nevada-there is some opposition due to its environmental
impact as well as it being an eyesore to local residents.
In large-scale energy storage deployment, the state of California
was the first to reach gigawatt-scale deployment
and achieved its 2020 1,325-MW energy-storage goal
ahead of schedule. California further projected 55,000 MW
of new storage by 2045. Arizona Public Service is planning
to install 850 MW of storage by 2025. Southern California
Edition (195 MW) and Pacific Gas and Electric (567.5 MW)
have received approvals from the California Public Utilities
Commission to build storage facilities.
Publicly available data from the U.S. Energy Information
Administration regarding battery storage only go as
far back as 2003, when the largest-and only-battery
facility in the United States had a nameplate rating of 27 MW
in the battery ESSs in Alaska. Within the past 10 years,
large-scale batteries have been installed at an exponential
rate, as depicted in Figure 2. They went from being
installed in only two facilities with nameplate capacities
under 30 MW in 2010, to having more than 1.5 GW of
nameplate capacity at more than 230 locations in only 10
years. This was driven largely by the falling costs of batteries,
which went from prohibitively expensive at more than
US$1,000 per kWh, to under US$200 over the same decade.
Therefore, from an economic perspective, it only makes
more sense to install storage systems in a fashion similar
to the precipitous decline in price for PV solar panels.
Financial and Operational Challenges
Although USES systems offer control and management
flexibility for system operators and equity and affordability
for customers, many challenges remain for the widespread
application and utilization of USES systems. The
biggest challenges relate to the management of energy
storage, distribution, degradation, and ownership, which
can result in greater financial benefits or in burdens for
the utility and customers. One of the biggest hurdles in
executing USES systems is developing and employing
business models that not only manage bills and agreements
between utilities and users but also allow utilities
and communities to benefit from energy charging/discharging
to provide a stable and resilient power supply
and necessary grid services. Although seemingly complex
by design, only a few studies have made efforts to design a
business model for shared battery storage.
Besides the economic considerations, challenges with
USES also arise from an operational perspective. USES
offers multiple potential applications, including firming
renewable generation, supporting frequency and voltage
profiles, mitigating transient stability, providing local blackstart
capabilities, enabling energy arbitrage, and enhancing
demand response. These applications are achieved at various
time frames and need to be carefully managed so that
the state-of-charge (SoC) of the battery system is maintained
at an optimal level to enable these applications
when needed. These can often create a conflict for the
stored energy among the intended applications. For example,
the battery should have an adequate SoC level when
an outage occurs and black start is called for, charging and
discharging rooms should be reserved so that the battery
can absorb or release energy in the range of renewable
variations the battery intends to mitigate, and the inverter
control should be designed to manage multiple functions
and coordinate competing objectives. Although none of
these needs are mutually exclusive, they can be close to
zero sum as prioritizing one need may come at the cost of
another. Ultimately, all of these applications translate into
financial terms, as either gained benefits or incurred costs
in the pursuit of an optimal solution. These costs and benefits
should be properly assessed and represented in the
business model for optimal financial performance and,
more importantly, provide incentives for USES to offer
these applications for any and all interested customers.
Environmental Challenges
Operational challenges are relatively well understood within
the industry, but there is no product without its
U.S. Battery Capacity
1,000
1,200
1,400
1,600
1,800
400
600
800
200
Year
Figure 2. The reported battery USES growth in the United States in
the past 20 years. The information was gathered from publicly available
U.S. Energy Information Administration data obtained from utility
companies.
IEEE Electrification Magazine / DECEMBER 2021
49
Nameplate Capacity (MW)
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
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IEEE Electrification - December 2021

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