AC/DC – alternating and direct current

Back in the 1700s, when Benjamin Franklin first discovered the electrical nature of lightning he found that it consisted of charge carrying energy from one place to another. Then Thomas Edison came along and invented the lightbulb, which could convert electrical energy into light. Charge flowed from a power source, through wires in one direction, to a device like the lightbulb, and then back to the power source with less energy than before. This is called direct current. But there was a problem.

When they tried to transport direct current across long distances lots of energy would get lost along the way. One way to minimize power losses when transporting it across long distances is to increase the voltage of the electricity. But at the time, the technology for increasing the voltage of Direct Current electricity was difficult to develop. Even a lightning strike could permanently damage a Direct Current transmission system. It was just too expensive to build and maintain.

To solve this problem two other inventors came along: Nikola Tesla and George Westinghouse. They had a new idea. Instead of letting current flow in only one direction why not make the current alternate directions very quickly? They developed alternating current, which meant that the direction that the charge flowed in would change frequently. Compared to direct current, increasing Alternating Current to higher voltages was easier to do and cheaper.

So most of the world settled for Alternating Current transmission systems. Even today that’s the case with most national power systems. Most household electrical appliances use Alternating Current power, which is why power sockets provide Alternating Current. But things have changed since the time of Tesla and Westinghouse. New technologies were discovered.

Now we use batteries a lot more. Ever wondered why chargers have that little box on them? It’s an adapter that converts the Alternating Current from your power socket to Direct Current. Because batteries need Direct Current in order to recharge. Converting between alternating current and direct current results in energy loss, which is why your charger gets hot after a while.

So why don’t we switch everything to direct current then? It’s not as easy as it sounds. It’s taken us decades to build AC power systems for entire cities. Changing to Direct Current would take a lot of time. But newer power stations, like the Three Gorges Dam in China, are being built with Direct Current transmission lines to distribute their power.

New technology makes it easier to transport direct current over great distances with minimal power loss. Tesla and Westinghouse might not be happy to hear about this shift but times have changed and Direct Current might be the way into the future. At least Franklin and Edison will finally have their way.