Seabrook, N.H.-based energy storage company SustainX Inc. announced Thursday that it has been issued 11 patents related to its constant-temperature compressed air technology.

The new patents brings to 23 the total number related to its isothermal energy storage system, which removes heat from air being compressed and returns it when that air is expanded to generate electricity, increasing efficiency, according to the company.

“We’re focused on bringing our grid-scale energy storage technology to market and a broad intellectual property portfolio is a key part of our strategy,” said President and CEO Tom Zarrella in a statement. “SustainX now holds more than 450 patent claims broadly applicable across our technology space, which we believe will make it quite difficult for competitors to challenge us.”

Last July, the company moved from Lebanon, N.H. into its current 42,000-square-foot site. Gene Hunt, director of communications for SustainX, told Mass High Tech that the 35-employee company is now building its first megawatt-scale system, which it expects to complete in the first half of 2013. The system will be connected to the electric grid in New Hampshire, and will be used to demonstrate the company’s proof-of-concept in order to eventually market the system to utility companies.

Founded in 2007 by [Professor Charles Hutchinson and engineering students Dax Kepshire Th'06, '09, Ben Bollinger '04 Th'04, '08, and Troy McBride Th'01] at Thayer School of Engineering at Dartmouth, the company received a $5.4 million grant from the Energy Storage Program of the U.S. Department of Energy in 2010, according to Hunt. In total, the company has gotten at least $30 million, with institutional backers including GE Energy Financial Services, Rockport Capital, Polaris Venture Partners, Cadent Energy Partners and General Catalyst Partners.