October 2016
Technology Advisory
Does My Co-op Have a Battery Energy Storage Application?
What has changed?
Battery energy storage is starting to emerge as an option for cooperative system
applications. As battery costs have dropped and battery technology has improved,
several co-ops have begun operating one or more battery storage systems to enhance
operations.
What is the impact on cooperatives?
The fundamental technologies underlying the Battery Energy Storage System (BESS)
continue to advance. New systems under development promise improved BESS
performance and new operational characteristics such as longer life, increased capacity
and faster recharge. Yet, BESS for utility applications is still a nascent and evolving
industry with no clear winners or losers. Given that level of uncertainty, cooperatives
must carefully assess battery technologies in terms of their ability to provide solutions
to existing and future challenges.
What do cooperatives need to know or do about it?
Until BESS products and vendors establish a track record, careful consideration of
commercial maturity will help assure that the selected BESS is a reliable and costeffective solution. Nevertheless, there are several applications for battery energy
storage at cooperatives that bear investigation for possible deployment.
Benefits of energy storage
Battery energy storage devices may provide a number of beneficial impacts for a
cooperative system. The benefits include improved reliability, enhanced value of
renewable energy sources, voltage and frequency support and control, and deferral of
major capital asset additions or replacements in addition to more traditional peak
shaving opportunities. As this technology advances, it is important for co-ops to
understand the impacts and key value propositions of storage that can assist in grid
planning and operations, meeting member-consumer needs in a cost-effective, safe and
reliable manner. What follow are some of the uses for battery energy storage that could
provide real system benefits.
Copyright © 2016 by the National Rural Electric Cooperative Association.
All Rights Reserved.
October 2016
Demand-Side Management – On the Distribution System (Front of the
Meter) or At the Consumer (Behind the Meter)
Energy storage devices can supply energy into commercial, industrial, agricultural and
residential loads to reduce the energy demand at any given time. The battery can be
located either on the distribution system in Front of the Meter, with the demand
management benefits flowing directly to the cooperative or it can be located Behind the
Meter at the load with the benefits being shared between the consumer and the
cooperative. In both cases, the value of the Energy Storage system is in the reduction
of demand or other “on-peak” charges. This application requires medium duration
energy capacities (of 2-4 hours). It would be appropriate for flow batteries, some
lithium ion battery technologies, advanced lead-carbon, aqueous-ion, various sodium
technologies, etc.
T&D Equipment Deferral – Distribution System Optimization via
Substation Storage
Substation energy storage can be an effective contributor to distribution system
optimization. For example, to mitigate limitations on substation load carrying capacity
due to a stressed transformer, a battery would be charged off-peak and discharged
downstream of the substation to reduce demand when the transformer is most
stressed, potentially adding years to the life the transformer. Another deferral strategy
is to avoid high cost three phase upgrades through use of batteries (and associated
DER) on the single phase feeder. Appropriate technologies for this medium duration
energy application include flow batteries, lithium technologies, advanced lead-carbon,
aqueous-ion and various sodium technologies.
PV Smoothing and Renewable Integration
Renewable generators can cause rapid fluctuations in the voltage of the grid due to
changes in generation, potentially causing problems such as customer voltage
excursions outside the ANSI voltage band or causing excessive cycling of voltage
control devices such as capacitors, voltage regulators and load tap changers. Deploying
energy storage can compensate for the fluctuations in generation, thereby mitigating
the above problems. Energy storage technologies suited for this include lithium-ion,
aqueous-ion, advanced lead-acid and other high frequency cycling-capable batteries.
Flywheels are also a potential energy storage technology that can be used for frequency
and voltage control.
Copyright © 2016 by the National Rural Electric Cooperative Association.
All Rights Reserved.
October 2016
Other Applications
Consideration may also be made of using battery energy storage as a source of revenue
in providing ancillary services to an integrated control area. Such systems, providing
frequency and voltage control, as well as operating and capacity reserves have been
deployed and demonstrated, using water heater controls and both on-site (behind-themeter) and utility scale battery storage devices. Such applications support distribution
system operator functionality, as well as interconnected systems operations.
What else should I be watching?
Growth in deployment of battery storage is expected by industry watchers: The details
are harder to nail down but there is ample evidence of regulatory- and market-driven
interest that is new. A broader perspective also is useful. Battery storage is a series of
technologies that will apply to address various uses and needs. But it is not the only
storage tool in the toolbox. A broader mix of storage resources – organized around the
term "community storage" – is also gaining currency. Community storage refers to
programs that aggregate distributed energy storage resources including batteries but
also including water heaters, ice and Electric Thermal Storage and electric vehicles to
improve the operational efficiency of electric energy services to consumers. More than
40 organizations including over a dozen cooperatives are engaged in the Community
Storage Initiative.
Tools and resources
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Energy Storage Use Cases – descriptions, specifications and methodologies to
perform cost benefit analysis for BESS applications (cooperative.com login)
o Distribution DSM
o Commercial DSM
o Distribution System Optimization via Substation Storage
o PV Smoothing
“Dispatchable” Solar Power – a new approach to the combination of solar power
and battery energy storage (cooperative.com login)
Energy Storage Lexicon – a common vocabulary for talking about electrical energy
storage systems (cooperative.com login)
Energy Storage Toolkit – resources to help cooperatives assess and implement
electrical energy storage systems (cooperative.com login)
Community Storage – news about the effort and who’s participating
(www.nreca.coop)
Contact for questions
Battery Energy Storage
Andrew Cotter, Storage Program Manager at [email protected]
Tom Lovas, Energy Storage Consultant at [email protected]
Community Storage
Keith Dennis, Senior Principal of End-Use Solutions at [email protected]
Copyright © 2016 by the National Rural Electric Cooperative Association.
All Rights Reserved.