This radical approach does require some expenditure on new technology, but the technologies involved are not complex and have been demonstrated to be reliable. One potential hidden cost is the heavier copper cabling required for 48 VDC distribution. As Joule's Law dictates, lower voltages require heavier conductors to carry the same power as higher voltages, due to higher amperage. Another cost factor with data centers is the higher voltage drop incurred over distance (about 20% per 100 feet), compared to AC. This is why the 48 VAC conversion is done in the rack rather than back at the utility power closet.
Of course, converting to direct current requires that your servers can accommodate 48 VDC power supplies. For some, converting to DC is a simple power supply swap. Chassis-based servers, such as blade servers, may be cheaper to convert because many servers share a single power supply. Google used the low-tech expedient of replacing server power supplies with 12V batteries, claiming 99% efficiency over a traditional AC-powered UPS (uninterruptible power supply) infrastructure.
If you're planning a server upgrade, you might want to consider larger systems that can be powered directly from 575 VDC, such as IBM's Power 750, which recently demolished human competitors as Watson on the "Jeopardy" game show. Brand-new construction enjoys the advantage of starting with a clean sheet of paper, as Syracuse University did when building out a data center last year, powering IBM Z and Power mainframes with 575 VDC.
Radical energy savings method 7: Bury heat in the earth In warmer regions, free cooling may not be practical all year long. Iowa, for example, has moderate winters but blistering summers, with air temperatures in the 90- and 100-degree range, which is unsuitable for air-side economization.
But the ground often has steady, relatively low temperatures, once you dig down a few feet. The subsurface earth is also less affected by outdoor weather conditions such as rain or heat that can overload traditional equipment. By sending pipes into the earth, hot water carrying server-generated heat can be circulated to depths where the surrounding ground will usher the heat away by conduction.