DC Microgrids and the Virtues of Local Electricity


It’s time to revisit Thomas Edison’s strategy for providing people with electricity.

It’s been more than a century since Thomas Edison lost the great technological battle he waged against George Westinghouse and Nikola Tesla, the now-famous “War of Currents.” The idea Edison hoped to defend was that the world should run off direct current (DC) electricity. But his position just couldn’t stand up to the pounding it took from the logic of Westinghouse and Tesla’s competing scheme, which was to produce and distribute alternating current (AC).

With an AC system, the fledgling electricity industry would easily be able to shift voltages from one level to another, allowing power to be carried long distances at high voltages, which would minimize transmission losses. When the electricity arrived at its destination, it could then be converted to the low voltages appropriate for use in homes and businesses. Lacking that ability, Edison’s DC system would have required the installation of an electric generator in every neighborhood so that the low-voltage current-carrying wires wouldn’t have to be more than a few blocks long.

Generations of electrical engineers have learned about Edison’s efforts to exaggerate the dangers of AC in an attempt to make people wary of it. But Edison had some great insights about electric power too. For example, he considered its sustainability long before this became a popular issue. “We are like tenant farmers chopping down the fence around our house for fuel, when we should be using Nature’s inexhaustible sources of energy—sun, wind, and tide,” he remarked in a 1931 conversation with Henry Ford and Harvey Firestone. “I hope we don’t have to wait until oil and coal run out before we tackle that.”

Many people have attempted to tackle sustainability problems by turning to various forms of renewable energy. But some of those sources—hydroelectric generating stations, wind farms, and solar-thermal power plants, for example—require large installations in places that are often far from population centers. That in turn demands the long-haul transmission and distribution of electricity to consumers. This is not difficult to accomplish, but it wastes energy. In the United States, transmission and distribution losses amount to about 7 percent.

Read more at: http://spectrum.ieee.org/green-tech/buildings/dc-microgrids-and-the-virtues-of-local-electricity

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