Need of Alternating current:

You might wonder why ac is even used. Is not it a lot more complicated than direct current?

Well, alternating current is easy to generate from turbines, as you have just seen. Rotating coil and magnet devices always produce alternating current, and in order to get direct current from this, rectification and filtering are necessary. These processes can be very tough to achieve with high voltages.

Alternating current lends itself well to being transformed to lower or higher voltages, according to the needs of electrical apparatus. It is not easy to change direct current voltages. Electrochemical cells produce dc directly, but they are impractical for the requirement of large populations. To serve millions of the consumers, the immense power of flowing water, wind, burning fossil fuels, the ocean tides, safe nuclear fusion, or of geothermal heat are required. All of these energy sources areused to drive turbines which turn alternating current generators.

Technology is getting advanced in the realm of solar electric energy; someday a important part of our electricity might come from photovoltaic power plants. These would generate direct current. There is 1 advantage to direct current in the utility applications.  This is for the transmission of energy over great distancesby  using wires. Direct currents, at very high voltages, are transported quite efficiently than alternating currents. The wire has less effective resistance with direct current than with alternating current, and there is less energy lost in magnetic fields around wires.

Direct-current high-tension transmission lines are considered for future use. Right now, the basic problem is expense. The sophisticated power conversion equipment is required.