Humans have used the mechanical energy of moving water for over 2000 years to grind grain, irrigate fields, and many other applications. Medieval civilizations further developed water wheel technology to crush ores for metallurgy, grind wood to pulp for papermaking, and to process lumber in sawmills. Bernard Forest de Bélidor, a French engineer, published the hydraulic machinery that would later be adapted for hydroelectric power in his book Architecture Hydraulique in the mid-1700s.
As the process was further refined, the world’s first hydroelectric project was completed in England in 1878, and used to power a single lamp. Hydroelectricity came to New Brunswick in 1881 with the construction of the Milltown Dam – the oldest hydroelectric dam in Canada. Hydroelectric generation has since blossomed into the highest capacity renewable energy technology worldwide, surpassing 1000 GW internationally. Canada has 76 GW of installed capacity, and New Brunswick contains just under 1 GW.
Hydroelectric dams
Hydroelectric dams are the most common and established hydropower technology for energy generation. As water passes through a hydroelectric dam, it spins a turbine generating electricity. There are 2 major types of hydroelectric dams: a conventional dam and a run-of-the-river dam.
Conventional dams store a large reservoir of water behind them, and allow some of the water to pass through. The raised water level, referred to as the head of the dam, provides the potential energy required for the water to flow through the dam. The passing water spins a turbine in order to generate electricity. A variation on the conventional dam is a pumped-storage dam, where some water from the reservoir is pumped through a turbine to generate electricity, rather than relying on the energy provided by the head.
Run-of-the-river dams instead are designed for the regular flow rate of the river, instead of creating a reservoir. Variations on the run-of-the-river dam are used for micro-hydro generating stations, which divert a section of the normal river through a turbine before re-joining the main waterway.
Tidal power
The rising and falling of the tides contain a large amount of energy that may be converted to electricity. There are a number of different generating station designs that can extract energy from tides. Tidal stream generators rely on the flow of water through a turbine to generate energy as the tides come in and recede. Tidal barrages channel the incoming tides into a basin, which is then closed off to prevent the water from leaving as the tide goes out. The water in the basin is then released similar to a hydroelectric dam, spinning a turbine to generate electricity as it exits.
There are currently very few tidal power generating stations, however the Bay of Fundy’s largest tides in the world are recognized for their incredible generation potential. Annapolis Royal Generating Station in Nova Scotia is the 3rd largest tidal power station in the world, with the capacity to generate 20MW (behind France’s 240MW Rance Tidal Power Generating Station and South Korea’s 254MW Sihwa Lake Tidal Power Station), and is located in the Annapolis Basin, a sub-basin of the Bay of Fundy. It is estimated that there is room for generating stations to produce approximately 7000MW in the Bay of Fundy — enough to supply power for all of Atlantic Canada.
Environmental impacts
A major concern with installing hydropower stations is the impact on the surrounding marine environments.
Flooding basins for reservoir dams can have a drastic impact on the local ecosystem. Displacing animals, changing water temperatures, drowning flora, and other land-use concerns are common when one of these dams is being installed. For run-of-the-river dams, migrating fish such as salmon can be blocked due to the new structure.
Damming bays for tidal generating sites can impact aquatic ecosystems, and may trap animals that accidentally travel into isolated areas. Certain tidal generators may also create currents that disrupt the surrounding ocean floor. Due to the wide variety tidal generating station design, an extensive local environmental assessment should be done to ensure that these generating stations do not have a negative impact on the surrounding ecosystem.
As with all technologies the manufacturing and end-of-life of hydroelectric structures can produce harmful greenhouse gas emissions. Hydropower plans have lifespans of 50–100 years, meaning that the clean energy they produce over this time helps to compensate for these emissions. With correct operational procedures, dams should not produce any waterborne pollutants during installation or removal.
