While datacenter power requirements are a major piece of the energy efficiency puzzle that the industry continues to work on, the issue of what kind of current, direct or alternating hasn't been on the radar for most of the history of the datacenter business. While telcos used DC for their equipment it wasn't common for the current model of datacenter customer to make use of anything but AC, regardless of how power was delivered to their facility.
High-voltage direct current (HVDC) is a de factor standard for long distance power transmission for a number of economic and technical reasons, but the power coming out of the outlets is still almost always AC. But advocates point out their there are cost savings to be found in using DC to power your datacenter, both in equipment and energy spending. ABB, one of the leading proponents of DC in the datacenter, partnered with Swiss datacenter operator Green to deploy DC power for their latest datacenter.
ABB considers this new datacenter to be a showcase of the potential for DC in the datacenter. Tarak Mehta, head of ABB's Low Voltage Products division, described it as providing the ability "to demonstrate that DC is a complementary technology in data centers as it enhances reliability while minimizing footprint, installation and maintenance costs."
On the IT side HP is the provider of computing and storage systems that can run on the 380v DC source. The HP X1800 G2 Network Storage System, HP DL385 servers, and the HP BladeSystem c3000 are all deployed in the new facility and are part of HP's Converged Infrastructure product model. HP feels that offering these systems with DC support demonstrates their commitment to finding the most energy and cost effective solutions for their customers.
The issues that led to the selection of AC over DC more than 100 years ago are still applicable in most situations. But in the special purpose world of the datacenter, where small savings in the cost of power can result in significant long-term benefit over the life of a facility, the advantages to DC become much more prominent. The technologies necessary for power delivery on this scale and at these power levels have changed since Edison lost the Battle of Currents in the 1880's, but it seems that the war continues.