Renewable energy Edison’s revenge

Inventor’s direct current makes comeback as it increases efficiency, lowers emissions

By SARA LEDWITH, Reuters December 26, 2011

At the start of the 20th century, inventors Thomas Alva Edison and Nikola Tesla clashed in the “war of the currents.” To highlight the dangers of his rival’s system, Edison even electrocuted an elephant. The animal died in vain; it was Tesla’s system and not Edison’s that took off. But today, helped by technological advances and the need to conserve energy, Edison may finally get his revenge.

The American inventor, who made the incandescent light bulb viable for the mass market, also built the world’s first electrical distribution system, in New York, using “direct current” electricity. DC’s disadvantage was that it couldn’t carry power beyond a few blocks. His Serbian-born rival Tesla who, at one stage worked with Edison, figured out how to send “alternating current” through transformers to enable it to step up the voltage for transmission over longer distances.

Edison was a fiercely competitive businessman. Besides staging electrocutions of animals to discredit Tesla’s competing system, he proposed AC be used to power the first execution by electric chair.

But his system was less scalable, and it was to prove one of the worst investments made by financier J. Pierpont Morgan. New York’s dominant banker installed it in his Madison Ave. home in the late 19th century, only to find it hard to control. It singed his carpets and tapestries.

So from the late 1800s, AC became the accepted form to carry electricity. For most of the last century, the power that has reached the sockets in our homes and businesses is alternating current.

Now DC is making a comeback, becoming a promising money-spinner in renewable or high-security energy projects. From data centres to long-distance power lines and backup power supplies, direct current is proving useful in thousands of projects worldwide.

“Everyone says it’s going to take at least 50 years,” says Peter Asmus, a senior analyst at Boulder, Colo.-based Pike Research, a market research and consulting firm in global clean technology. But “the role of DC will increase, and AC will decrease.”

The main factor driving demand is the need to conserve energy and produce more of it from renewable sources. Alternating current is generated by rotating engines, but renewable sources such as wind and solar produce DC power. To use it, because of the way our buildings are wired, we first convert it to AC.

Another thing that’s happened since Edison’s time is the advent of the semiconductor. Semiconductors need DC power, and are increasingly found in household appliances. These have to convert the AC supply back to DC, which is a waste of energy and generates heat. In the early years of industrialization this wasn’t an issue, but today it’s important, especially in the huge and fastgrowing business of cloud computing.

The companies that handle our information traffic are racking their brains to boost efficiency and cut carbon emissions from their plants. Pike Research expects the green data centre business to be worth $41 billion annually by 2015, up from $7.5 billion now.

Finnish information technology company Academica, for instance, has a data centre in a granite cave beneath Helsinki’s Uspenski cathedral. It uses Baltic Sea water to cool the plant and feeds surplus heat to the city’s homes. IBM has designed a solar array to power its Bangalore data centre. Microsoft has filed a patent application for a windpowered data centre.

Direct current may be one way to increase efficiency and reduce emissions. Right now, outside a handful of universities, it’s not the first thing people are thinking of because there are more basic things to do, says Eric Woods, Research Director for Smart Industry at Pike. But for companies on the leading edge, “it’s sort of coming out of the research ghetto.”

Pike has not put a figure on how big the DC component of the green data centre market will be. Swiss-Swedish engineering firm ABB, a big DC advocate, says about 35 per cent of demand for green data centres will come from the United States, 30 per cent from Europe, and the rest spread globally.

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