Alternating Current (AC) vs. Direct Current (DC) refers to the direction in which electrons move across our transmission lines. AC is a wave of electrons flowing back and forth across the lines, while DC is the constant flow of electrons in only one direction. The majority of today’s grid uses AC lines. DC lines are often single lines and therefore some have suggested greater use of DC to cut down on the overall footprint of transmission. However, there are some limitations to DC transmission. For example, DC lines require expensive converters to get their electrical energy onto the grid. Also, AC lines can accept power from multiple generation sources and transmit it to multiple load centers, allowing for much greater energy transfer over longer distances. DC lines do not allow for easy redirection of power in the event of a line outage. AC lines have the ability to balance power to ensure reliability and avoid a cascading effect of power failures.