Though humans have been harnessing water to perform work for thousands of years, the evolution of modern hydropower began in the late 1800’s–coincidentally at the same time that Thomas Edison and Nikola Tesla were embroiled in a battle now known as the War of the Currents.

Edison developed direct current (DC)–current that runs continually in a single direction—like in a battery. During the early years of electricity, direct current was the standard in the United States, but there was one problem: direct current is not easily converted to higher or lower voltages needed to deliver power to houses and office buildings.

In came Tesla, who believed that alternating current (AC) was the solution to this problem. Alternating current reverses direction a certain number of times per second and can be converted to different voltages relatively easily using a transformer.

Seeing alternating current as a threat to his direct current patents, Edison began a campaign to discredit alternating current. He spread misinformation saying that alternating current was more dangerous. But when Edison lost the bid to power the 1893 World’s Fair in Chicago to electrical pioneer George Westinghouse, alternating current powered the event and took hold thereafter.

The breakthrough of alternating current--the method used today--allowed power to be transmitted over longer distances, ushering in the first U.S. commercial installation of an alternating current hydropower plant at the Redlands Power Plant in 1893. The Redlands Power Plant in California utilized Pelton waterwheels, driven by water from the creek and a 3-phase generator, which ensured consistent power delivery.

The past century of hydropower has seen a number of hydroelectric advancements that have helped it become an integral part of the renewable energy mix in the United States. Find out more about the last 100 years of hydropower with this interactive timeline.

Sarah Wagoner
Contributor page for Sarah Wagoner, former Communications Specialist for the Water Power Technologies Office.
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