WEST LEBANON, N.H.--()--SustainX, Inc., developer of an industry-leading, transformative technology for utility-scale energy storage using compressed air, today announced that it has received a U.S. patent giving it control over a technology combining cogeneration with isothermal compressed-air energy storage to turn waste energy into electricity. Another new patent establishes the company’s ownership of a control system for maintaining constant power to and from its energy storage system.
“This will allow us to help renewable energy projects fulfill their power requirements and existing fossil fuel plants to operate in a more environmentally-friendly manner.”
Cogeneration is the production of electricity using energy left over from some other process. For example, a conventional power plant discards heat not intense enough to make steam, wasting about 60 percent of the energy released from its fuel. SustainX storage technology can turn a portion of this waste heat into electricity, supplying a storage function and a cogeneration function at the same time. It is the only utility-scale energy storage option that can harvest additional electricity from low-grade heat.
“This cogeneration patent allows SustainX to expand the type of systems it develops, providing more market options,” said Dax Kepshire, Vice President and co-founder of the company. “This will allow us to help renewable energy projects fulfill their power requirements and existing fossil fuel plants to operate in a more environmentally-friendly manner.”
A SustainX isothermal (constant-temperature) energy-storage system can cogenerate because it removes heat from air being compressed for storage and adds heat to air being expanded. The heat added during air expansion, when the system is generating electricity, can come from any source—including a conventional power plant. Within limits, the more heat is added, the more extra electricity is produced.
Cogenerative SustainX storage installed at a conventional power plant will convert excess power to energy stored as compressed air, enabling the plant to run on a more even, efficient schedule. At times when higher electric output is needed, such as peak-demand periods, the SustainX system can release energy from storage while harvesting low-grade waste heat to boost its electric output. A conventional plant enhanced with SustainX storage can thus serve as a low-cost “virtual peaker,” supplying extra electricity at high efficiency during periods of high demand—a service usually provided by costly, dedicated peaker plants burning natural gas. Higher power-plant efficiency means less pollution and lower cost for each unit of electricity produced.
The second new patent describes a scheme for controlling a SustainX storage system’s hydraulic drivetrain at constant power. Controllable constant electric power improves the economic value of generated power and can simplify isothermal compression and expansion based on the required rate of heat transfer. Together, the two patents improve the flexibility and performance of SustainX’s novel heat-exchange technology: cogeneration allows it to recover more energy, while constant-power cycling simplifies its operation.
“There is growing consensus that the U.S. and the world need to quickly transition to a cleaner energy paradigm featuring more solar power, wind power, and other renewables,” said Kepshire. “SustainX will enable that future by supplying a key energy source at times when the sun doesn’t shine and the wind calms, and by supporting more efficient operation of grids and conventional power plants. These two patents show that we are making fundamental innovations without neglecting the subtleties that add up to competitive performance.”
SustainX was founded in 2007 by engineers from 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 investors Polaris Venture Partners, Rockport Capital, Cadent Energy Partners, General Catalyst Partners, and GE Energy Financial Services.
SustainX has received six US patents to date on core aspects of its technology, solidifying its leading position in the field of compressed-air energy storage. The patents cover a wide range of isothermal systems, including both existing SustainX systems and those in development. The three-year-old company is on track to demonstrate its first one-megawatt, grid-connected system in collaboration with AES Energy Storage, LLC under an award from the Energy Storage Program at the US Department of Energy.
SustainX’s transformative energy storage technology, which it terms ICAES™ (for Isothermal Compressed-Air Energy Storage), uses no fuel. The company’s competitive advantages stem from its patented 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 fuels.