Think of it as the poor man's ice air conditioner.

Air conditioning startup IceCycle, formerly known as Trinity Thermal Systems, has created an ice air conditioning system that can be retrofitted onto existing air conditioners. It also uses a remote cooling tank that can hold liquids from water to antifreeze, according to CEO Richard Hahn, who spoke last week at the Clean Energy Venture Summit in Austin, Texas.

Using liquid coolants from a separate tank could reduce costs of installation, he said – picture tanks on the ground and pipes leading up to an air conditioner that doesn't have to be replaced with a crane.

If it works, it could help continue to popularize one of the more intriguing ideas in air conditioning. Ice air conditioners produce heat at night when power is cheap. During the day, the chill from the melting ice is conveyed via heat exchangers through a building to cool it.

Air conditioning can be 30 percent of a building's power consumption on a hot summer day, so they also help utilities avoid peak power situations. Utilities in fact are considering programs under which they would pay the cost for replacing an existing air conditioner for an ice-powered one. (see Will Utilities Pay for AC Upgrades?). Peak shaving is actually the big advantage of these systems.

Calmac, one of the oldest companies in the business, has installed ice systems in 3,500 buildings. The Bank of America Tower in New York installed Calmac's ice-powered coolers. In Hawaii, a 210,000 square foot Nordstrom's will be cooled by 43 tons of ice produced a night. Tata Consultancy Services, the technology branch of the Indian conglomerate, is putting the company's system in its new research facility in Bangalore.

Meanwhile, Ice Energy has raised about $60 million in venture investment and has units being deployed by major HVAC companies, such as Honeywell in Southern California Edison territory and Trane in Pacific Gas & Electric territory (see Ice Energy Picks Up Cool $33M for Hybrid AC).

IceCycle, on the other hand, has raised only $600,000 so far to fund a few electric co-op pilots since 2005, and is seeking $700,000 more to expand its pilots, Hahn said. Still, the technique it outlines could reduce the overall cost of replacing the old AC unit.

Austin Energy will be pilot testing both IceCycle and Ice Energy's Ice Bear units, Kurt Stogdill, the utility's manager of strategic planning and enterprise development, said. That could give the two technologies a chance to duke it out, head to head.

Austin Energy has been running underground chiller plants at night to cool downtown offices since the 1990s, John Baker, the utility's chief strategy officer, said.

Photo of an IceCycle Retro installed on an existing building air conditioning system via the company.