Microsoft is relying on green technologies in its newest datacenters, including one in San Antonio where it is breaking ground on Monday.

The San Antonio building, one of several in the works at various locations, will be 500,000 square feet and contain tens of thousands of servers, said Michael Manos, senior director of datacenters at Microsoft. The company announced it would build the center in San Antonio earlier this year.

The first phase of the facility will be operational in July next year, he said.

Microsoft's software plus services and Windows Live initiatives are driving these construction efforts, which will support the online services, he said. Microsoft is not alone among Internet services companies building new facilities to support hosted services. Google and Yahoo have also both announced development of new large datacenters.

Microsoft uses 31 different criteria in choosing datacenter sites. While Manos couldn't describe them all for competitive reasons, access to environmentally friendly resources is one.

In San Antonio, Microsoft plans to use recycled water, sometimes called gray water, in its cooling systems. The option, which allows the use of water that is not fresh or drinkable but is not contaminated by any toxic substances, is offered by the local utility. It is considered environmentally friendly because it reduces demands for fresh water and doesn't consume the energy required to purify it at waste water treatment sites.

In addition, a significant portion of electricity in Texas is generated by wind, and that clean source of energy was attractive to Microsoft, Manos said.

The San Antonio facility will be one-third the size of a massive datacenter that Microsoft is building in Quincy, Wash. That center will be nearly carbon neutral, meaning it doesn't produce more carbon than it consumes. Electricity used at the Quincy datacenter will be generated by hydroelectric plants, which are commmon in western Washington. The center won't quite be totally carbon neutral, however, because the company uses diesel-powered generators for backup and must test those now and again, Manos said.

Last week Microsoft confirmed that its construction company in Quincy switched to biodiesel to fuel cement trucks and other equipment in order to solve a health and safety problem. At that site, builders erected the walls and ceiling of the structure before laying the floor. Cement trucks, originally using petrodiesel fuel, were letting off exhaust that would be harmful to workers who were inside the enclosed building. Switching to biodiesel, which has cleaner exhaust, solved the health and safety issue at the site.

Manos wasn't sure if Microsoft would continue to use biodiesel at the Quincy site or other locations. Generally, the company plans to continue using such green technologies. "There is a great alignment between going green and being economical," he said.

At some datacenters, Microsoft has systems that use outside air, if it's cool enough, to help regulate the temperature in the building rather than solely using air cooling systems.

About 75 jobs will be available at the San Antonio facility. But Microsoft likes to consider the broader affect on local economies. The facilities often bring business to other nearby companies, such as those that might service generators. In addition, not long after Microsoft announced that it was building in Quincy, Yahoo and Intuit also decided to build datacenters there.

Microsoft has other new datacenters "in the works," but none that it is ready to talk about just yet, Manos said.