WEST LEBANON, N.H., Dec. 1, 2010 /PRNewswire/ -- SustainX, Inc., a New Hampshire-based startup that is developing a transformational technology for utility-scale energy storage using compressed air, has received its second patent. U.S. Patent No. 7,832,207 covers staged expansion and compression of gas during energy conversion, a core component of SustainX technology.
In representative systems protected by the new patent, energy is stored by using it to compress air through a series of stages. Each air stage is handled by a separate pneumatic cylinder containing a piston or other boundary mechanism. The first-stage piston compresses air to a moderate pressure, the second-stage piston to a higher pressure, and so on. Later, to release energy, the compressed air is expanded through the same staged cylinders, from high pressure to low. Coupled air and hydraulic staging makes it possible to operate the cylinders, pumps, and other devices in the energy-storage system at peak efficiency.
SustainX's previously issued patent, U.S. Patent No. 7,802,426, protects constant-temperature (isothermal) methods of energy storage using compressed air. When gas is compressed, it tends to heat up; when it is expanded, it tends to cool down. Isothermal compression removes heat from the gas as it is being compressed in order to keep it from heating, and adds heat to the gas as it is being expanded to keep it from cooling. In both cases the goal is to maintain the gas at a steady temperature. Heat for isothermal expansion can be harvested from water, air, or a source of waste heat such as a fuel-burning power plant.
Separately or together, isothermal operation and coupled air and hydraulic staging increase the round-trip efficiency of energy storage using compressed air to levels never before achieved.
SustainX was spun out of the Thayer School of Engineering at Dartmouth College in 2007 and has received funding from the National Science Foundation (NSF) Small Business Innovation Research (SBIR) Program, the Energy Storage Program at the U.S. Department of Energy (DOE), and equity investments from top-tier venture investors Polaris Venture Partners and Rockport Capital.
The company's transformative energy-storage technology, which it terms ICAES™ (for Isothermal Compressed-Air Energy Storage), uses electrical energy to compress air near-isothermally (i.e., at approximately constant temperature), stores it aboveground in commercial gas storage containers, and expands it near-isothermally to generate electricity. No fuel is involved. The company's competitive advantages stem from their proprietary thermodynamic and hydraulic control innovations, a design centered on mature industrial components, and reliance on an 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.
SOURCE SustainX, Inc.