Hydroelectricity

Water: a sensible choice for economic, social and environmental reasons

The very first hydroelectric power plant was built in the United States in 1882, by H.J. Rogers, based on a concept developed by Thomas Edison. Canada was not far behind, and the first Canadian hydro plant was opened in 1885 at Montmorency, Quebec. Over the years, advances in civil, mechanical and electrical engineering have made Canada a world expert in the field. Hydroelectricity is now the main energy source in the country, accounting for close to 60% of national production.

People have been using the power of moving water to run water wheels and mills for more than 2,000 years. Modern power plants today convert that mechanical energy into electricity.

Tides, ocean currents, waterfalls, rivers… Moving water is a constant source of energy ready to be harnessed. Hydroelectric energy is obtained by using a turbine to convert the kinetic energy of a river or waterfall into mechanical energy, and then an alternator to transform it into electrical energy.

There are two main kinds of hydroelectric generating stations: reservoir, and
run-of-river (ROR).

A generating station with reservoir uses a dam to create an artificial lake. Water is collected seasonally and used to meet sudden, significant and ongoing demands for electricity. A run-of-river generating station has no reservoir but offers the advantage of producing electricity without having to store the water.

Hydro power plants produce minimal greenhouse gases and are a source of clean, non-polluting energy. The evaporation/condensation cycle also makes hydro energy renewable. The above qualities pertain particularly to ROR plants, which produce energy from the natural water flow, which means that the impact on the landscape, ecosystem and neighbouring communities is considerably reduced. It also costs much less to produce electricity at an ROR plant.

Such properties make ROR hydroelectricity a sensible choice, for economic, social and environmental reasons.

How a run-of-river power plant works

Run-of-river generating stations are not very complicated. Flowing water is channelled through the intake and enters a penstock, which causes it to flow with greater speed and force to the turbine. The turbine is activated by the force of the water, and it, in turn, runs the alternator to produce electricity. The water then flows down the tailrace and returns to the river.

The viability of a site and the electricity it can produce are determined by two factors: drop height and water flow volume.

Generally speaking, one megawatt (“MW”) of hydroelectricity is enough to meet the annual needs of about 400 Canadian households (one household consuming an average of 12 megawatt-hours (“MWh”) per year).