What do you do with a 54-foot-long ice cube?

Carve it into a sculpture of the SS Titanic? Chill the world's largest bowl of punch? Sell lots of snow cones?

Officials at Howard Community College in Columbia have come up with a better idea: Use it to cool three of the school's buildings. Through a new technology called ice thermal storage, a device at the school forms the giant cube at night, when electricity costs less, then uses the slowly melting mega-cube to air condition buildings during the day.

The "ice chiller" machine, cranked up last June, will reduce the school's energy costs by $30,000 a year, college President Dwight Burrill told reporters, college officials and business people attending a briefing on the device this week.

The college's ice storage system, manufactured by Jessup-based Baltimore Aircoil Company, works on the simple concept of "make hay while the sun shines" or, in this case, make ice while the moon shines. Since electricty costs far less at night, when demand is low, than during the day, companies -- or schools -- save money by generating some or all of the energy a building uses at night, storing that energy up, than slowly using it during the day.

The ice chiller, or "the big ice cube" as its operators call it, freezes water in a 54-foot metal container during energy-cheap night hours, then uses the resulting giant ice cube to chill water used to air-condition buildings during the day, reducing the school's use of expensive, peak-period energy, said William McCloskey, executive vice president of Baltimore Aircoil.

Each of the buildings cooled by the device will use on average about 22 percent less energy due to the device, McCloskey said.

Part of the college's savings will come from incentives Baltimore Gas & Electric Co. grants users of the system, college officials say. With energy use scheduled to reach total capacity during this decade, the utility encourages the use of thermal storage systems. BG&E, for example, offers to pay for feasibility studies and provides energy rebates for companies using the system.

Ice has been used to cool buildings since the 1930s, when churches, theaters and dairies fanned blocks of it to cool people or products. While thermal storage systems have been around for 10 years, the college's device is unusual because it is compact, more efficient than past systems and relatively cheap -- HCC's cost about $100,000 -- Baltimore Aircoil officials said.

The company has installed similar systems at Johns Hopkins Applied Physics Lab in Laurel.