Alternators and Alternating Current enabled the long-distance transmission of electricity. Edison’s electrical plant ran on DC which does not transmit far. Under Edison’s system, there were electric plants every few blocks in cities (the inner Chicago loop had 25 electric plants at one point). Tesla’s AC system transmitted electricity much further; it’s the same we use today at both power plants, transmission, and in homes and businesses.
Background
There are two basic types of electricity, Direct Current (DC) and Alternating Current (AC).
DC current flows in one direction making it easier to work with and arguably less likely to electrocute people, two important factors for early electrical pioneers. Edison built his electrical plant and equipment using DC.
However, DC cannot be transmitted far without the electricity fading away. In the earliest days of electricity, where electrical plants were for businesses and wealthy people located in city centers, this hardly mattered. At one point, there were 25 electrical plants in the Chicago loop. Manhattan had electricity plants.
The European team ZBD had developed and patented an efficient an inexpensive method for AC generation and transmission. George Westinghouse, who had become wealthy innovating a better brake for trains but was hoping to move into the field of electricity, licensed the patent and went into business, competing against Edison’s DC plants (and patents). Another AC company was the Thomson-Houston Electric Company, that also relied on AC.
Tesla & Westinghouse
Westinghouse continued building AC plants and infrastructure and soon came across a young immigrant who had worked briefly for Edison then left to work on his own electrical innovations, Nicola Tesla. Tesla believed that AC electricity was far more practical than DC. He worked on innovating AC generators, transmitters, switches, appliances: everything required to build an AC electrical grid. He also built an AC motor, which electrical engineers at the time though impossible.
This brought about two competing electrical standards, AC and DC. Edison and Tesla each tried to sell their standard leading to the infamous “War of the Currents.” At one point, things ran so out of control that Edison, a capital punishment opponent, suggested New York State contact Westinghouse to build an AC electric chair, demonstrating the inherent danger of AC. Edison proposed using the term “Westinghoused” rather than electrocuted.
Centralized Electrical Plants
Over time, the benefits of a central large electrical plant became obvious (see: Insull). Generating electricity at one large central facility, then distributing it widely, is more efficient. Since this model did not work for DC, which could not be distributed more than a few kilometers, AC won out. Eventually, Thomson-Houston merged with Edison Electric company to form General Electric; the company focused on AC. Edison never showed up to work after the merger.
Today, AC electricity is what powers the houses and factories of the world though there are still limited largely low-voltage uses for DC electric. In any event, AC and DC are now largely interchangeable; while wall sockets are AC, computers, phones, tablets, and LED lamps run on DC power.