The Direct Current was the earliest form of electrical current used. Direct current refers to an electrical charge which flows in one direction only. Direct current was very useful for transferring consistent amounts of power over short distances, but the electrical current could not be converted to lower voltages, and bled large amounts of energy when traveling long distances, which heated the wires and caused fires. (1). The inability to convert also created problems with appliances. The voltage of an electrical current is inversely proportional to the wattage, meaning lower voltages produce more heat. (2) Any appliance made for use with direct current that was hooked up to a power source with too little voltage ran the risk of overheating and/or catching fire. These issues prevented direct current electricity from becoming commercially viable for most products.
Direct current devices did find their place, however. Batteries and solar cells both are only capable of producing direct current energy. Any Battery or Solar powered device uses direct current.
1)AC/DC: What’s the Difference? PBS. http://www.pbs.org/wgbh/amex/edison/sfeature/acdc.html
2)Brian, Marshall. Harris, William. Lamb, Robert. How Electricity Works. http://science.howstuffworks.com/electricity8.htm