Hugh Pickens writes "Most companies buy servers from the likes of Dell, Hewlett-Packard, IBM or Sun Microsystems, but Google, which has hundreds of thousands of servers and considers running them part of its core expertise, designs and builds its own. For the first time, Google revealed the hardware at the core of its Internet might at a conference this week about data center efficiency. Google's big surprise: each server has its own 12-volt battery to supply power if there's a problem with the main source of electricity. 'This is much cheaper than huge centralized UPS,' says Google server designer Ben Jai. 'Therefore no wasted capacity.' Efficiency is a major financial factor. Large UPSs can reach 92 to 95 percent efficiency, meaning that a large amount of power is squandered. The server-mounted batteries do better, Jai said: 'We were able to measure our actual usage to greater than 99.9 percent efficiency.' Google has patents on the built-in battery design, 'but I think we'd be willing to license them to vendors,' says Urs Hoelzle, Google's vice president of operations. Google has an obsessive focus on energy efficiency. 'Early on, there was an emphasis on the dollar per (search) query,' says Hoelzle. 'We were forced to focus. Revenue per query is very low.'"