Canada's Energy Mix

Tidal

The highest tides in the world are found in Canada’s Bay of Fundy, where 160 billion tonnes of water flow in and out twice a day! Did you know that this flow can be used to produce tidal energy?

Shawn Harquail, Minas Basin, https://www.flickr.com/photos/harquail/28459114941/, (CC BY-NC 2.0)

What is tidal energy and how is it used to produce electricity?

Tidal energy works by harnessing the power of ocean tides, which are caused in large part by the gravitational pull of the moon, as well as the sun and the rotation of the earth. Tidal energy is renewable, meaning that the water used for energy production is not used up in the process and is infinite.

Tidal power generating stations are installed along coastlines in areas with a large tidal range. Electricity is generated from ocean tides when water passes through a barrage. The change between low tide and high tide causes water to flow through a turbine. This movement of the water (which is kinetic energy) turns the blades of a turbine. The turning of the turbine (mechanical energy) powers a generator that produces electricity.

Tidal energy is reliable because it happens twice a day—two low tides and two high tides within about 24 hours. The science behind harnessing tidal energy is still in its infancy and research is being done to determine how to make the process more efficient.

How does the electricity travel to where it needs to go?

There are three stages in the electricity system — generation, transmission, and distribution. Generation is about producing electricity, transmission is about moving it, and distribution is about delivering it to individual customers.

Transmission lines carry electricity from generating stations to end users or consumers. When electricity is running through these lines, some electricity is lost due to resistance and dissipates as heat. To reduce the amount of electricity lost in transit, these transmission lines carry high voltage electricity.

Power generators produce low voltage electricity and in order for this electricity to be transported to where it needs to go, the voltage has to be increased. A “step up” transformer is used to convert it to a higher voltage that the transmission lines can carry. Once the electricity reaches its destination, a substation “step down” transformer converts it back to a lower voltage so that it can be used by consumers.

The last part of the electricity grid is the distribution network, which is essentially the network of wires that takes the electricity from the transformers and carries it to the end-users. Electric utilities are private companies or government organizations that handle the production, transmission and distribution of electricity. Managing the electricity grid is a complicated process and an important responsibility.

Canada is connected to the United States through an international network called the North American Power Grid. Along the U.S. border there are more than 35 transmission connections, which allow for a flexible and mutually beneficial trade in electricity between Canada and its neighbour.

What is the electricity used for?

Electricity is used in our homes and businesses for things like lighting, heating and cooling, and powering appliances and electronic devices. We live in a world dependent on electricity. From the refrigerator in your kitchen and to the computer that you’re using to access this website, electricity is the thing that makes possible most of our modern-day conveniences.

Jacob Earl, Annapolis Royal Tidal Station, NS, https://www.flickr.com/photos/athoos/3920374595/, (CC BY-NC-ND 2.0)

How does tidal energy production impact the environment?

Tidal energy is a renewable resource and its production does not directly contribute to climate change, but the manufacturing and set-up of a tidal station does produce some greenhouse gas emissions (e.g., transporting the turbines to the site location). Tidal turbines can have a harmful effect on wildlife, specifically fish, but it is relatively low and doesn’t pose a huge threat to marine populations. There are ways to mitigate the effect on wildlife such as with careful site selection, to avoid disruption to animal migration routes. This a new energy source and there is still more research that needs to be done into its repercussions for marine life. One advantage of tidal power plants over other renewable energy sources is that the station itself takes up a relatively small amount of land (as opposed to wind and solar farms).

Where do we find tidal installations in Canada?

The Annapolis Tidal Power Plant is the only tidal power station in North America. Located in the Bay of Fundy, which has the highest tides in the world, the station has a generating capacity of 20 megawatts of electricity.

Did you know?

Canada is one of the few countries in the world that uses tidal energy!