Hydroelectricity is obtained from the energy contained in falling water; it is a renewable, comparatively nonpolluting energy source and Canada's largest source of electric power generation. In N America in the 1850s the energy content of moving water was exploited through the use of small-capacity waterwheels and turbines for the direct drive of machinery, for example, in gristmills and sawmills. By the 1860s many hundreds of turbines, ranging up to 1000 HP capacity, were manufactured annually in the US and by the early 1870s the production of at least one Canadian factory was averaging about 20 machines per year. Hydroelectricity was introduced in the 1880s, soon after Thomas Edison began manufacturing direct-current (DC) electric generators, which were initially belt driven by steam engines. It was not long before enterprising mill owners began to install generators of up to 10-12 kW capacity, with belt drives from existing mill turbines, to provide electric lighting in the mills and adjacent premises.
