Switching from AC to DC
IT gear runs on DC (direct current), but utilities provide electricity as AC (alternating current).
Normally, "A UPS converts the 3-phase 480vAC coming from the power utility to DC, to charge its batteries, and then reconverts back to 3-phase 480vAC to send it through the data center. The PDU (Power Distribution Unit) for each rack or row of racks converts the 3-phase 480vAC to 3-phase 208vAC, which is what normally goes into IT gear like servers and storage arrays. And the power supplies in the IT gear converts that 208vAC into 380vDC," says Dennis Symanski, Senior Project Manager, Electric Power Research Institute, and chairman of the EMerge Alliance's committee writing the 380vDC standard.
Various initiative are underway exploring going, ahem, directly from utility power. "We've done a lot of demos worldwide about running data centers at 380vDC (volts of Direct Current) instead of 208vAC," says Symanski.
Moving to a direct current infrastructure says Symanski, "gets rid of three conversion steps in the electrical system, and also reduces the load on the air conditioning by the reduced amount of heat being created.
What's that mean in terms of dollar savings? "We've found in most of our demonstrations that we get about a 15% reduction in the power used to run IT equipment. Plus the savings from needing less air conditioning, which are probably comparable, but harder to measure.
Since a DC infrastructure means DC UPSs, DC circuit breakers, DC interconnect cables, et etc., data centers are unlikely to convert existing AC set-ups, other than as testbeds, says Symanski. "This is for when you are expanding in your data center, like adding a new row of racks, or building a new data center."
Switch to power-saving components
There are many opportunities to reduce power consumption simply by replacing some of the components in existing power and cooling systems.