Santa Clara, Calif.--Here's a novel idea. Some cities are examining the possibility of installing data centers, those energy-gobbling server rooms we all rely on, on mothballed ships. Although high-speed lines would have to be extended to the docks, the energy savings would be tremendous because these ship-bound data centers would need far less air conditioning than standard data centers. Air conditioning accounts for 33 to 50 percent of the power that gets pumped into data centers. The air is cool in many of the world's seaports. More important, ships sit in the water.  "It (a ship) has the biggest heat sink in the world beneath it," said Subodh Bapat, who oversees Sun's green and energy efficiency efforts. Sun is hosting a data center energy summit today. For the past two years, Sun has been touting the energy efficiency message hard.  In another place, a municipality is contemplating taking the hot water that gets produced in data centers and pumping it--after filtration--into its public pools. The water that comes from data centers never gets hot enough to crank turbines, but it's warm enough for applications such as this.  Ambient air cooling with air-side economizers is also gaining traction. In San Francisco, one study noted that ambient air is cool enough to cool server rooms in that city 8,500 hours a year. Cooling is only needed 8,760 hours a year, he said. Thus, anyone building data centers there can whack their electrical costs by designing the building with passive air cooling in mind. (Microsoft earlier this year told me that they were going to take advantage of ambient air cooling in a new data center going up in Ireland.) Ambient air can also be amplified with a technology called earth pipes. With earth pipes, air gets pumped into a miles-long network of pipes approximately 30 feet underground. The air gets chilled there and then comes up to cool off the server room. (Side note: the ancient Egyptians used a similar technology.) Even with the cost that comes with filtering the air of particles and moisture, ambient air is still cheaper than air conditioning, according to Bapat. Other companies are also implementing the ice cube concept. In this, cheap electricity at night is used to run ice makers. The ice then melts during the day: the cool air acts as air conditioning. Remember sticking your head in the freezer as a kid and breathing in the air? Same concept. And here's another idea: let computers tolerate warmer air, according to Dean Nelson, who runs the global lab and datacenter design services at the company. If they can live in warmer temperatures, less air conditioning is needed.