AC versus DC was one of the few losses inventor Thomas Edison had to the genius Nikola Tesla, but it is about to get a rematch.
The pair slogged it out with Edison backing his DC system while Tesla plumped for alternating current. Tesla won, mostly because his system was safer and could be used to distribute power over longer distances.
According to Reuters, Edison might have the last laugh thanks to the development of renewable or high-security energy projects. From data centres to long-distance power lines and backup power supplies, direct current is coming back.
Peter Asmus, a senior analyst at Pike Research, a market research and consulting firm in global clean technology, was quoted as saying that it will take another 50 years but DC will increase and AC will decrease.
Alternating current is generated by rotating engines, but renewable sources such as wind and solar produce DC power which has to be converted to AC.
To be fair to Tesla, Edison had it wrong at the time. DC has only become viable since the advent of the semiconductor which are found in all our modern gadgets. Semiconductors need DC and have to convert the AC supply back to DC, which is a waste of energy and generates heat.
During Edison’s time this was not a problem, but now with cloud computing and data centres it is a bit of a headache.
Direct current may be one way to increase efficiency and reduce emissions. It is being tested in a few universities.
DC power could make a difference at higher voltages because of its ability to run on renewable energy sources on microgrids. These are almost certain to take off soon, particularly in countries which are not densely covered by AC grids, such as Australia and India. In developing countries they can be used to replace costly and wasteful diesel generators.
Power electronics, or semiconductor switching devices, make it possible for DC to be transmitted at high voltage over very long distances, longer than AC.
DC still has technological limitations that need to be fixed. There is a bit of a problem in the US where standard voltages are already much lower than in Europe and there is a shortage of cable-making capacity. But it could be that Edison has the last laugh after all. A pity really, Tesla was much more interesting. Television made him into a vampire and the movies made him into a magician. Edison just gets away with the fake accreditation of inventing the lightbulb and making Tesla’s life a misery.