SustainX Receives Control System Patent for Energy Storage Technology

By Sustainx, PRNE
Monday, March 21, 2011

Fourth Patent for Three-Year-Old Entrepreneurial Venture

WEST LEBANON, New Hampshire, March 22, 2011 - A fourth patent has been awarded by the US government to SustainX, a
fast-growing technology venture in Lebanon, New Hampshire. SustainX has
developed a transformational technology for utility-scale energy storage
using compressed air. The new patent covers methods for controlling the way
air is expanded and compressed in such systems.

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Energy storage is essential to making the electrical grid more efficient,
according to the US Department of Energy, but affordable storage technologies
have so far been lacking. To meet this need, SustainX compresses air by using
electricity to drive pistons inside cylinders. The resulting high-pressure
air is stored in above-ground vessels. To release energy at a later time, the
system uses stored air to drive the same pistons, which in turn drive an
electric generator.

The company's new patent, No. 7,900,444, covers the use of measurements
of conditions inside the cylinders, such as temperature or pressure, to keep
the air at a nearly constant temperature during compression and expansion.
One method for controlling the air's temperature is to spray water through
it. By maintaining near-constant ("isothermal") air temperature, SustainX
significantly improves the efficiency of compressed-air energy storage.

"This patent, along with the three others awarded to SustainX during the
last year, further establishes the company as the world leader in isothermal
compressed-air energy storage," says President and CEO Thomas Zarrella.

This new patent, combined with previously issued patents on staged
compression and expansion and on heat exchange with a thermal well or the
environment, strengthens SustainX's IP position in the field of
compressed-air energy storage. The issued patents are general enough to cover
a wide range of isothermal systems, including both existing SustainX systems
and those in development.

About SustainX

SustainX was founded in 2007 by engineers at the Thayer School of
Engineering at Dartmouth College
. It has received funding from the National
Science Foundation Small Business Innovation Research Program and the Energy
Storage Program at the US Department of Energy, as well as equity investments
from top-tier venture investors Rockport Capital (with offices in Menlo Park,
and Boston), Polaris Venture Partners (Boston and Seattle), Cadent Energy
Partners (Stamford, CT and Houston), and GE Energy Financial Services, a unit
of GE.

The company's transformative energy storage technology, which it terms
ICAES(TM) (for Isothermal Compressed-Air Energy Storage), uses no fuel.
SustainX's competitive advantages stem from its proprietary thermodynamic and
hydraulic control innovations, a design centered on mature industrial
components, and reliance on ambient-temperature, nontoxic working fluids.

SustainX ICAES is targeting the emerging market for bulk (grid-scale)
energy storage being created by the growth in renewable generation, and aims
to disrupt costly "peaker" plants that burn natural gas or other polluting

Dax Kepshire, Vice President, SustainX, Inc., +1-603-276-3393, dax at

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