War of the currents: AC/DC power

13th June 2016
Jordan Mulcare

Steve Jobs and Bill Gates - two of the most well-known figures in modern technology and also, one of the industry’s most infamous rivalries. “The only problem with Microsoft is they just have no taste,” Jobs famously stated in 1996. Despite the snide remarks and occasional lawsuits, both Jobs and Gates realised there was room on the IT market for both companies to coexist. The same however, cannot be said for George Westinghouse and Thomas Edison. Arguably two of the brightest minds in science, the pair engaged in a decade-long vendetta over alternating (AC) and direct (DC) electrical currents.

More than a century later, Darren Halford, sales manager of industrial automation supplier EU Automation, discusses the war of the currents and its implication on modern data centres.

Fuelled by the fear of losing his fortune, in the late 1880s Edison began a propaganda campaign to convince the public that AC power was deadly – despite DC power being equally dangerous. In spite of brutal demonstrations, AC came out on top. Now, over a century later, DC power is finally beginning to make a comeback, but this time, on its own merits.

Any device that uses transistors relies on the direct flow of electricity that DC power provides. Accounting for up to 20 per cent of the world’s total power consumption, consumer devices such as PCs, smart phones and televisions rely on DC direct current. To some extent, our growing taste for consumer technology is responsible for the steep growth of DC.

However, the growing popularity of DC power is not limited to user level. With high voltage transmission lines, DC power provides more efficient and lower construction costs than its AC alternative. Currently, AC is the standard for transmitting electricity around the grid and to many industrial devices, like electrical motors. However, as industry struggles to increase efficiency, while maintaining or improving availability, DC power is now seen as an opportunity to save energy. By distributing DC power to DC devices, rather than converting it to AC along the way, companies can avoid substantial energy losses.

Another driver for DC power is the growing number of data centres around the world. Currently consuming 1.3% of electricity globally, data centres are growing in size and capacity. Data centre managers are currently converting the incoming AC power from the grid by using large centralised converters to distribute DC power across their facilities. However, by replacing AC/DC converters with more efficient, centralised inverters, energy consumption can be reduced by up to 15%.

The benefits of DC power for the data centre are clear. Financially, DC power applications are cheaper to install, operate and maintain than AC alternatives. What’s more, there is no need to adapt capacity to account for phase balancing or harmonics, as they are not a factor with DC power. As data centres enter a new stage of maturity, where reliability and delivering a higher capacity is vital, DC power seems to be the obvious solution to lower costs and reduce power consumption.

However, not all experts are convinced the DC uprising will truly take shape anytime soon. In developed countries, where the AC power grid has already been well established for over a century, the logistical problems of changing large parts of the existing grid from AC to DC could make the changeover tricky.

While there may not be a global transformation of the power system to DC on the cards anytime soon, there is no denying that for many modern organisations, direct current is a fundamental part of the IT infrastructure: with critical loads consuming DC power and back-up sources generating it.

Ultimately, the delivery of DC power from the grid may not be as unlikely as sceptics believe. For developing economies, that are building completely new power infrastructures, the potential benefits of implementing DC power grids are certainly appealing. But for now, the war of the currents continues to rage on.

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