“Perpetual power” from the tides in Boston, Massachusetts, USA, 1813–1858

Abstract

From 1822 to 1858, a “perpetual power” system supplied continuous, uniform tidal power to Boston industries. A 2.4 km dam in the Charles River estuary and a shorter cross dam formed two basins. Industries drew water from a “full” basin that was replenished at high tide, passed it through breast wheels, and discharged it to a “receiving” basin that emptied at low tide. Unlike owners of conventional, intermittent tide mills, who sold services or products, the managers of this system sold energy to industrial customers, as modern utilities do. They created new opportunities for Boston’s inventors and artisans, and the roads built on their dams became important transportation links for the city. Yet the project also degraded the estuarine environment and generated complaints about pollution. When population growth and falling costs for steam power made the extensive basins and mill sites more valuable for urban development than for generating renewable energy, a novel earth-moving process filled the basins to form Boston’s prestigious Back Bay district. This little-known, unique tidal-power development overcame daunting technological challenges in a period when American civil engineering was in its infancy.