IEEE Power & Energy Magazine - September/October 2017 - 52

applications in both countries present valuable technical and
institutional lessons for developing EES around the world.
Pumped-storage hydropower currently provides the majority of grid-level EES capacity in both countries; however,
battery energy storage systems (BESSs) dominate the recent
growth in EES installations. This article focuses primarily
on BESS development in both countries.

Visions and Trends for Grid-Scale Energy
Storage in the United States and China
EES Technologies in the United States
Over the last eight to ten years, the U.S. energy sector has
demonstrated substantial progress in developing EES technologies as well as greater clarity concerning the role these technologies can play in integrating variable renewable resources,
ancillary service markets, energy management, infrastructure
upgrade deferrals, and other applications and services. These
developments, coupled with an increasing number of demonstration projects for storage technologies in transmission and
distribution applications throughout the United States, have 1)
increased stakeholder awareness about the role of EES and 2)
shown the ability of EES to deliver cost-effective performance
in select applications and markets.
EES systems are expected to play an increasing role in
successfully integrating large amounts of variable renewable
resources (mainly wind and solar) into existing and future
electric grids. A utility-scale EES provides grid services
that will be valuable in addressing the operational and reliability challenges resulting from large-scale integration of
renewable generation, such as resource variability, temporal
mismatch between generation and demand, forecast uncertainty, and stability impacts. The large-scale implementation
of energy storage can also help reduce the level of wind and
solar power curtailment caused by transmission congestion,
overgeneration, or minimum generation thresholds for conventional power plants.
The U.S. Department of Energy (DOE) is continuously
refining its strategy for developing and demonstrating EES
system technologies. Long-term goals focus on the following:
✔✔ EES technologies should be cost-competitive with
other technologies providing similar services.
✔✔ An equitable regulatory environment is necessary to
fully utilize the value proposition of EES.
✔✔ EES should be fairly compensated for its value in providing multiple stacked benefits.
✔✔ EES should seamlessly integrate with existing systems, leading to its widespread deployment.
The U.S. Federal Energy Regulatory Commission (FERC)
has been developing regulatory mechanisms for operators of
wholesale power markets, thus enabling the use of EES technologies in capacity, energy, and ancillary service markets.
In 2011, FERC enacted Order No. 755, which increases the
payment for fast-responding resources such as flywheels and
batteries. In 2013, FERC issued Order No. 784, which directs
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independent system operators (ISOs) to monetize services by
such fast-responding technologies, including EES. The recent
FERC policies have had a significant impact.
In 2015 in the United States, new energy storage totaling
221 MW was installed, of which 160 MW are being deployed
in the PJM Interconnection regional transmission organization
(RTO). High penetrations of wind generation on the electric
grid will result in an increasing expectation that large-scale
wind power plants provide grid-support ancillary services.
The recently released FERC Order No. 819 revises regulations to foster competition in the sale of primary frequencyresponse services; this means that RTOs and ISOs will need
to encourage fast-responding resources to provide multiple
ancillary services using a market-based methodology.
The U.S. electric power sector is complex, from both the engineering and institutional perspectives. There are differences
in regional generation mixes, regulatory and market environments, amounts of storage, and ability to transfer power to and
from locations with diverse load profiles. These differences impact the adoption momentum of EES technologies on a regional
basis. For example, in 2010, the California Public Utilities Commission (CPUC) adopted a policy for California utilities and
load-serving entities to consider the procurement of viable and
cost-effective ESS technologies. In 2013, the CPUC established
an energy storage target of 1.325 GW for three major investorowned utilities [Pacific Gas and Electric Company, Southern
California Edison (SCE), and San Diego Gas and Electric]. The
Energy Storage Roadmap-adopted by the CPUC, California
ISO, and California Energy Commission-identifies policy,
technology, and process changes to address challenges faced
by the storage sector in achieving the targeted deployed storage
capacity by 2024.
In 2016, New York State adopted its own energy storage
road map; it recommends specific actions for the EES technology industry, policy makers, and stakeholders to ensure
realization of the benefits of energy storage. In particular,
the road map establishes goals of having 2 GW of multihour
storage capacity on New York's electric grid by 2025 and
4 GW by 2030.
In 2012, PJM implemented FERC Order No. 755, which
requires payment for performance, and changes its rules in
frequency regulation market. The new rules differentiate
between fast-responding resources (such as energy storage)
and conventional resources in providing frequency regulation and offer higher payments for fast-responding resources
because of their higher performance capabilities.
The Electric Reliability Council of Texas (ERCOT) is
in the process of launching new ancillary service markets
to provide a comprehensive suite of services for enhanced
grid reliability. Fast-acting energy storage devices are envisioned as playing an important role in these new markets in
Texas because of their ability to provide timely and accurate
responses to sudden changes in system frequency or other concerns. Hawaii is another promising market for storage because
of temporal price differences and reliability challenges
september/october 2017

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - September/October 2017