Duke Energy Renewables completes Notrees Battery Storage Project in Texas; North America's largest battery storage project at a

  Duke Energy Renewables completes Notrees Battery Storage Project in Texas;
        North America's largest battery storage project at a wind farm

PR Newswire

CHARLOTTE, N.C., Jan. 23, 2013

CHARLOTTE, N.C., Jan. 23, 2013 /PRNewswire/ --Duke Energy Renewables, part of
Duke Energy'sCommercial Businesses, announced today the completion of its
36-megawatt (MW) energy storage and power management system at its Notrees
Windpower Project in west Texas. The system completed testing and became fully
operational in December, 2012.

(Logo: http://photos.prnewswire.com/prnh/20040414/DUKEENERGYLOGO )

"Battery storage is an important innovation to address the variability of wind
and solar energy generation," said Duke Energy Renewables President Greg Wolf.
"Developing an expertise in this advanced technology will enable us to expand
the use of renewable energy, better integrate it into the power grid and
become even more efficient at serving our customers."

In late 2009, Duke Energy announced plans to match a $22 million grant from
the U.S. Department of Energy (DOE) to install large-scale batteries capable
of storing electricity produced by the company's 153-MW Notrees wind farm,
located in Ector and Winkler counties. The grant was made possible by the
American Recovery and Reinvestment Act of 2009.

"Completion of this project represents a singular success for Duke Energy, for
the DOE, and for the entire energy storage community in the U.S.," said Dr.
Imre Gyuk, program manager for energy storage at the U.S. Department of
Energy. "It will demonstrate the capability of energy storage to mitigate the
variability of wind energy and to contribute to the stability of the grid."

Austin-based Xtreme Power designed and installed the 36 MW-capacity Dynamic
Power Resource™ at Notrees and will continue to operate the system. The
battery storage project will help mitigate the variability of wind power,
storing excess wind energy and discharging it whenever demand for electricity
is highest.

In addition to increasing the supply of renewable energy during periods of
peak demand, the system will help stabilize the frequency of electricity
traveling throughout the power grid. Duke Energy is working closely with the
Energy Reliability Council of Texas (ERCOT), which signals to the battery
storage system to either dispatch stored energy to increase frequency or
absorb energy to decrease frequency.

The Electric Power Research Institute (EPRI) will collect performance data
from the battery storage system and help assess the potential for broader
adoption of energy storage solutions throughout the industry. Technical and
economic data will also be analyzed for DOE by Sandia National Laboratory.
Results from the storage project at Notrees wind farm will be shared
publically through the DOE's Smart Grid Information Clearinghouse.

About Duke Energy Renewables
Duke Energy Renewables, part of Duke Energy's Commercial Businesses, is a
leader in developing innovative wind and solar energy generation projects for
customers throughout the United States. The company's growing portfolio of
commercial renewable assets includes 15 wind farms and 14 solar farms in
operation in nine states, totaling more than 1,700 megawatts in
electric-generating capacity. Learn more at www.duke-energy.com/renewables.
Headquartered in Charlotte, N.C., Duke Energy is a Fortune 250 company traded
on the New York Stock Exchange under the symbol DUK. More information about
the company is available on the Internet at: www.duke-energy.com.

About DOE ARRA Storage Projects.
DOE's Office of Electricity Distribution and Energy Reliability (OE) has the
mission to lead national efforts to modernize the electric grid, enhance
security and reliability of the infrastructure, and facilitate recovery from
disruptions to energy supply. As part of this mission, OE has awarded 16
grants for energy storage projects under the American Recovery and
Reinvestment Act of 2009 (ARRA) for a total of $185M. Each project is at least
50% cost shared. The projects cover diverse technologies such as compressed
air energy storage, flywheels and advanced batteries. Applications include
frequency regulation, smoothing of a photovoltaic installation, ramping for
wind, and time shifting for a fossil fuel plant. ARRA projects are an integral
part of OE's Energy Storage Program. Project management is provided by the
National Energy Technology Laboratory (NETL).

About Xtreme Power
Founded in November 2004, Xtreme Power designs, engineers, installs, and
monitors integrated energy storage and power management systems for
Independent Power Producers, Transmission and Distribution Utilities, and
Commercial & Industrial End Users, among others. Xtreme Power's technology
delivers on its promise to solve complex grid challenges and our customers
rely upon our staff of over 100 power systems engineers and professionals to
design and implement a solution specific to each customer's need.

Xtreme Power is a privately held company and has raised in excess of $90
million since its founding. Current investors includeSAILCapital Partners,
Bessemer Venture Partners, The Dow Chemical Company, BP and Fluor, among
others. These multimillion-dollar investments have yielded tremendous growth
and accolades, including the following: Bloomberg 2012 New Energy Pioneer
Award, R&D 100 Award, one of 4,000 companies selected for the Global Cleantech
100 Award, and most recently honored by Inc. Magazine as the 15^thfastest
growing company in the nation. For more information, please visit

Duke Energy  Tammie McGee 980-373-8812
             24-Hour       800-559-3853
Xtreme Power Mavis Baah    202-628-1280

SOURCE Duke Energy

Website: http://www.duke-energy.com
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