DOE Backs Electrochemical Developer

A Minnesota manufacturer of energy efficient, electronically tintable window glass was recently selected for a $72 million Department of Energy loan guarantee. Sage Electrochromics Inc. will use the support to expand manufacturing of its windows that use an electrochromic technology, based on the transfer of lithium ions across a five-layer substrate, to block visible light and thermal energy.

The Faribault, Minn., company plans to quadruple the size of its manufacturing plant to 250,000 square-feet, says a company official. The funding will allow Sage to move to high-volume production as well as nearly double the maximum size of its window panes to 5 ft by 10 ft sheets.

Buildings use about 40% of the nation's energy and DOE estimates energy lost through conventional windows accounts for 30% of heating and cooling energy. The tintable system can cut building heating and cooling systems energy use by 25%. The importance of and market for such chemistry-based, energy saving technologies are growing globally (C&EN, Nov. 17, 2008, page 15).

According to DOE, Sage is the manufacturer of the world's first commercially available tintable window glass, which is controlled through a low-voltage and programmable electrical system. Founded in 1989, Sage has installed window systems around the U.S. and the expansion will allow the company to move to high-volume production, a company spokeswoman says.

When low voltage is applied to the ultra-thin layers in their "clear" state, the layers darken as lithium ions and associated electrons transfer from an inner layer cathode to an outer electrochromic electrode. Reversing the voltage polarity causes the ions to return to their original layer and the glass is made clear again. When fully tinted, some 98% of thermal energy is blocked from entering a room, the company says. The five layers in total are less than the thickness of a human hair.

This loan guarantee marks the seventh to be issued by DOE. The guarantee is conditional and Sage must line up financing to supply at least 20% of the $110 million needed for the expansion.

When announcing Sage's guarantee, DOE also said it would also provide up to $117 million in loan guarantee support for a 30 MW wind farm and electricity storage system to be built in Hawaii.