Hydroelectric generation, similar to wind, relies on the rotation of a turbine by a moving fluid. As water runs downstream, dams capture its kinetic energy and convert it to electricity. Due to its terrain and possession of few major rivers, Rhode Island has little reserves of hydropower. States in the Pacific Northwest are leaders in hydropower, utilizing the major rivers that run through their states. In 2016, seven hydroelectric power plants contributed 6.7 megawatts capacity in Rhode Island. In the United States, relatively few dams are built for electricity production, so Rhode Island may have the opportunity to advance hydropower at some of its dammed sites. Despite this potential, the estimates for Rhode Island’s hydroelectric reserves total between 10 and 20 megawatts, and should not be considered a major contributor to Rhode Island’s renewable portfolio.

There are environmental risks associated with hydropower systems. Dams can disrupt the ecology of a river, affecting fish migration, silt, water characteristics, and the wildlife associated with that river. Fish kills associated with turbines is a serious concern, with solutions like fish ladders and hatcheries being implemented more widely. Apart from emissions associated with manufacturing and currently-researched methane from reservoirs, hydropower is renewable and emissions-free, a vital source for a future less dependent on fossil fuels. Alternative forms of hydropower, including tidal, wave, and ocean thermal energy conversion, are exciting prospects that are still in development.