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Duke Energy Leverages Maxwell Ultracapacitors to Launch the Next Generation of Grid Energy Storage Systems

Duke Energy Leverages Maxwell Ultracapacitors to Launch the Next Generation of Grid Energy Storage Systems

| Dr. Kimberly McGrath, Director of Business Development

Utility scale energy storage is a nascent but rapidly growing market—from $347 million in 2015 to over $1 billion by 2020 in the USA.1 As an increased number of demonstration, pilot, and commercial deployments are commissioned, utilities and solutions providers alike will benefit from the value and practical use of energy storage across a number of utility side of the meter applications. The most important of these include real-time solar and wind smoothing, stacked utility services, energy shifting,  and fast response applications including instantaneous voltage sag and power quality remediation, transmission and distribution stabilization and frequency regulation.  

Duke Energy, the largest investor-owned utility in the United States, recently deployed a hybrid battery-ultracapacitor energy storage system at a distribution substation in Gaston County, N.C. This hybrid system leverages the ultracapacitors to perform solar smoothing at the distribution circuit in real-time—particularly when the solar power on the grid fluctuates due to cloud cover or other weather circumstances. The batteries are simultaneously used to perform energy shifting of a large solar system on the distribution circuit. This system combines the high power, fast response ultracapacitors with energy dense batteries (in this case, aqueous hybrid ion batteries provided by Aquion) to maximize utility system value by offering simultaneously occurring grid services at a lower system cost. This system is intelligently integrated by Win Inertia’s advanced power electronics and their management and control system to optimize this hybrid combination of batteries and ultracapacitors.

Specifically, deployment of ultracapacitors in hybrid systems provide technical and economic benefits including:

  • Solar integration services – this includes the mitigation of short term, rapidly occurring  events of solar facility power output
  • Extension of total energy storage system lifetime – by removing high peak power load from the battery with the ultracapacitors
  • Reduced capital expenditure – batteries no longer need to be oversized to accommodate high power performance/heat stress over a long lifetime
  • Reduced operating expenditure – ultracapacitors are designed for over five hundred thousand cycles2 with the added advantage of long operational life in a wide operating temperature window
  • Capacity assurance – by supporting battery performance, ultracapacitors mitigate battery capacity degradation over time, thereby decreasing the risk that energy is not available to meet demand (can lead to monetary performance penalties)

In summary, the use of a stand-alone battery system is typically deployed for energy time-shifting applications. However, by simultaneously providing high power, short-term response by batteries alone may lead to excessive degradation that requires battery oversizing. The use of a hybrid battery-ultracapacitor solution significantly reduces battery degradation by using ultracapacitors for compensating most of the solar smoothing events in such a manner that:

  • The total energy throughput for batteries is reduced
  • The thermal stress caused by high C-rate responses is mitigated

Maxwell looks forward to supporting utilities in their priority to bring more renewable energy generation and stacked services to the grid in a reliable, cost-effective manner.

Maxwell Technologies Energy Solutions for the Grid - Brochure

Wolfgang BeezDr. Kim McGrath
Director of Business Development
About this author

Dr. Kim McGrath is director of business development for Maxwell Technologies and has spent her career in the field of energy storage applications and technology development. She received her doctorate in chemistry from the University of Southern California and an MBA from The Paul Merage School of Business at the University of California, Irvine.

1Source: GTM Research, U.S. Energy Storage Monitor: 2015 Year in Review Executive Summary
2Results may vary.  Additional terms and conditions, including the limited warranty, apply at the time of purchase. See the warranty details for applicable operating and use requirements.

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