February 21, 2007 3:58 AM PST
This tub, from Transphase Phoenix, is filled with water permeated with different kinds of salts so it will freeze at 47 degrees rather than the conventional 32 degrees. The water is turned into ice at night when electricity is cheap. It's then allowed to melt in the day, when it provides air conditioning to a building. The tubs are meant to be stacked. The idea is to reduce peak demand in the afternoon, when electricity is more expensive, and obviate the need for "peaker" plants.
Photo by Michael Kanellos/CNET News.com
